.L.J,, . ueva. Juan lu1s Delgado, lbrahim Akubat, Pieter Jacobs, Pim Koolwijk, l icvcn De Vcirman, Anâré Aubert, Peter Catteeuw, Guido Seerden, stcvcn Probst, Malhicu Gram, Rcnaldo Landburg, Glen Reed, Sally Hara, Bart De Roover, Balder Bcrckman.,, f.'>ter l owetle, Arne Jaspers, John Fitzpatrick, Kyle Woodruff Faculdade de Despow Universidade cio Por+c Serviços de PGQUITlênracão FITNESS IN SOCCER THE SCIENCE AND PRACTICAL APl'llCATION [IPORTO l 1 li~lil1li1\i i~Íl lllll lllll llll llll :9:~:32227ü.;9; DE PO!~TO SERVIÇOS DE DOCUMENTACAO Nº .Q . .z..z;Z,.,~.Q. D!-\TA %./Q2?.1fbllí Jan Van Winckel, Werner Helsen, Kenny McMillan, David Tenney, Jean-Pierre Meert, Paul Bradley FACULDADF OE DESPORTO DA UNIVERSIDADE DO PORTO FOREWORD "Trairzing is an exact science and relies on reason. Coaching is an art and comes fro111 the heart. A good coach should be a reasonable artist." Prof Mart Buekers lsbn-number: 9789082132304 Publisher: Moveo Ergo Sum I K!ein-Gelmen Proofreading: Jim Newall Quill Content IWriting, Editing and Web site services http://YNN1.quillsites.co.uk Photos: Jean Leemans and Etienne C!aessens Cover and lay-out: Dots & Bits © 2014 Jan Van Winckel While writing and revising this book, I often thought of the almost poetic words above. As a soccer coach, you often tread a thin line between what has been proven scientifically and what is consi<lered "best practice." Unfortunately, science in soccer is still in its infancy, and there are still many question marks in this regard. Soccer is a very complex sport in which different physica1 abi1ities are used in tandem, often competing for adaptation. Because not everything in the field of soccer science has been "mapped out'' yet, we often have to rely on our experience and intuition. I hope this book can help in some small way to make you a better "reasonable artist." During the discussions on how we would promete the book, the publisher asked me for some quotes from coaches I have worked with. Although you will find some, I felt I would rather not do this. I prefer to sincerely thank all the coaches, board members, physicians, physiotherapists and other staff I have worked with for the knowledge they have given me and for their marvelous cooperation. I have, it seems, purloined a little piece of kno\.vledge from each of them. I would also like to thank the coauthors of this book-Kenny, Dave, Jean-Pierre and Pau1-who have spent considerable time writing and reviewing this book. It is thanks to their knowledge and effort that this book has been a success in Belgium and Holland, success that will hopefully be repeated in the rest of the world. Special thanks to Wemer Helsen, who has been my friend and mentor for over 20 years. Finally I would like to thank my wife, Ester, for supporting me in everything I have done. My thanks also goto my parents, Anita and Hugo. They gave me the chance to study over the years, sacrificing many things in their own lives for my brothers (Bart, Tom and )elle) and me. For ]osephine and Bente, jan Printed and bound ai Manipal Techno!ogies lld., lndia AI/ rights reserved. No part of this book may be reproduced or transmítted in any fonn or by any means whatsoeverwíthout express written pennission from lhe au!/Jor, except in the case of brief quotations embodied in criticai articles and reviews. Pie ase refer ali pertinent questions to the publisher. USJ OF AUJllORS Steven Probst, MSc, has a master's degree in sports physiotherapy and rehabilitation sciences from the Katholieke Universiteit Leuven. Since 2009, he has worked for TopSportsLab as a research and development manager. Aside from this, he is involved as a sport physio and rehab coach in the youth academy of Oud-Heverlee Leuven, a Belgian first-division club. Píttt Koolwijk, MSc, has a master's degree in human movement science from the VU University Amsterdam and a bachelor's degree from the Sport Academy in The Hague. Since 2007, he has \Vorked as an exercise physiologist/physical trainer at FC Utrecht, which performs in the highest Dutch division. ln the past, he has worked as a human movement scientist at several sporting organizations. He still works as an independent sports consultant for several sporting organizations and individual athletes in the Netherlands. He has severa} specializations, including Strength and Conditioning Coach NSCA, Tennis and Skiing. Guido See1·den has a master's degree in Human and Movement Science (specialized in Sport & Exercise) and has also had a research internship at Liverpool John Moores University. He cooperated \.vith LJMU's Science and Football department during his final project about talent development in soccer. He has completed further intemships, such as at Tranmere Rovers FC, where he 1vorked as a fitness coach and sports scientist. He is currently working in Saudi Arabia as the Head Coach of the U9's and UlO's at the Al-Ahli Saudi football club. Steven Va111tarett is a certified strength and conditioning coach, a physical soccer coach, and a soccer-periodization expert. He has worked with U17 and U21 teams in the Belgian premier league. He worked at K. Sint-truidense VV as head coach and physical coach (2010-2012). After this, he became assistant coach/ strength and conditioning coach of the first team at Ujpest FC in the Hungarian premier league (2012-2013). He currently works as field training specialist and physical coach at the Al-Ahli Saudi football club in Saudi Arabia (2013-). Mathieu Gra111, MSc, holds tvvo mas ter' s degrees: one in Physiotherapy & Rehabilitation Science and one in Physical Education & Kinesiology. He has been active as a Sports Physiotherapist and Rehabilitation specialist at the Al-Ahli Saudi football club. Prior to this, he worked as a Sports Physiotherapist at the West Coast Eagles AFL club in Perth, Westem Australia. Alberto Me11dez-Villanueva, PhD, is a Senior Football Fitness Coach and Sports Scien- tist at the ASPIRE Academy and Qatar Football Association in Doha, Qatar. Before this, Mendez-Villanueva was the head of the Football Physiology Unit at the ASPIRE Academy. He holds a doctoral degree in sport physiology from the University of Oviedo in Spain anda master's degree in exercise physiology from the University of Westem Australia. He has published over 60 peer-reviewed scientific articles. He has also presented nearly 50 lectures on team strength and conditioning and physiology-related issues. Kyle Woodruff, BSc, has a bachelor's degree in Kinesiology frorn the University of Connecticut. He has worked as a physical coach for the Al-Ahli Saudi football club and also as an assistant for the men's and women's soccer and basketball teams at UConn. Lieven De Vein11a11, FAFS, has a certificate in Applied Functional Science from the Gray Institute in Adrian, Michigan. He has worked mainly as a personal trainer for lower levei athletes and is currently a strength and injury-prevention coach at the youth academy of the Al-Ahli Saudi football club. André E A11be1·t, PhD, has a doctorate in physics frorn the Katholieke Universiteit Leu- ven, Belgium, where heis currently emeritus professor at the Faculty of Medicine. His rnain research domains are cardiovascular sport physiology and the cardiovascular condition of astronauts, both on Earth and during the weightless conditions of space. Peter Catteeuw, PhD, \vas awarded his doctorate in sports sciences in 2010 from the University of Leuven. He has worked as a research and development rnanager for TopSportsLab in the field of performance management. As physical coach, he \Vas active in the youth tearns of K Lierse SI( (2004-2007) and RSCAnderlecht (2007-2009). Since 2011, he has \vorked as physical coach for the first team of KRC Genk. Carlo Buzziclielli, is an invited professor of "The Theory and Methodology of Training" at the Sport University of Camaguey and the Center of Football Studies at Camaguey, Cuba. He is technical director of the Tudor Bompa Institute, International. ln 2012, he was invited as a guest speaker to the "International Workshop on Strength & Conditioning" (Trivandrum, India) and to the University ofSao Paulo and the Olympic Center of Sao Paulo (Brasil). As an S&C coach for tearn sports, Carlo's tearns have achieved eight promotions, as well as a first and a second place in their respective league Cups. As a coach of individual sports, Cario has contributed to the World Track & Field Championship and the Cornmonwealth Games. His athletes have won sixteen medals in the national championships of four different sports (track & field, S\Vimrning, Brazilian jiujitsu, and powerlifting), as well as tvvo international gold rnedals (track & field), one silver and one bronze (Brazilian jiu-jitsu), setting five national records (in powerlifting). Juan Luis Delgado joined the ASPIRE Academy in 2007. He has held diverse positions as a soccer coach and worked with different groups from U13 to U17, developing players for Qatar' s national junior tearns. ln 2013, he was appointed as coordinator of the ne\vly created Scouting Department. Part of this ne'"v responsibility included the complete structuring and strategic setup of the department. Prior to this (1999-2006), Juan began his coaching career at Villarreal CF in Spain, working in several positions including both academy and first-tearn level. He then moved to Valencia CF where he worked as academy training methodology coordinator. He graduated from Valencia University with a bachelor' s degree in Sport Sciences and a minor in soccer. He also holds a master' s degree in Sports Psychology from UAM, Madrid. He is currently undertaking his doctoral thesis on "Football Tactical age-related differences." ln line with his soccer education, heis a UEFA Pro accredited coach and has enjoyed coaching development opportunities in the Netherlands and the US. Ibraltint Akubat, PhD, has a doctorate in exercise physiology, focused on training load monitoring in soccer, from the University of Hull, UK. He has examined a whole portfolio of dose-response relationships with physical, perceptual and biochemical measures in rested and fatigued states, all of which will be published in due course. He is now a lecturer in exercise physiology at Newman University, Birmingham anda consultant to numerous teams and athletes. He is also the founder of Training Impulse, a company providing information, workshops, training and software for matters related to training load monitoring. Renaldo Charles Landburg is a former athlete from the Netherlands. After finishing his study at the Central Institute of Sport Instructors (CIOS) he has completed courses to specialize in running technique, coordination and fitness in soccer. Following his work at many amateur clubs in the Netherlands, Louis van Gaal and Danny Blind approached Renaldo in 2004 to come and \.Vork for the youth academy of AFC Ajax, Amsterdam. After this \.VOrk atone of Europe's best youth academies, he decided in 2010 to move to Saudi Arabia, where he continues to work for the Al-Ahli Saudi football club as physical coordinator of the youth teams. Glen Reed, MSc, ASCC, has a mastens degree in strength and conditioning (S&C) from Middlesex University, London. He currently works in youth soccer, serving as the S&C coach for the U16 squad of Crystal Palace, where he has also had experience with the first team (2009-2010). Prior to this, he worked in the area of tennis at Highgate Performance Tennis (2011) and Hills Road High Performance (2011-2012). Sally Hara, MSc, RD, CSSD, COE, is a board-certified specialist in Sports Dietetics and a certified diabetes educator. She has bachelor's degrees in both Nutrition Science and Exercise Physiology, as well as a master's degree in Nutrition Science, all from the University of Califomia, Davis. Sally has worked in research laboratories and medical centers and has run a private practice, where she provides medical nutrition therapy and sports nutrition coaching, near Seattle for over 10 years. As a nationally recognized public speaker, former college instructor, and writer, she has authored and co-authored multiple research studies and sports nutrition articles. She is a contributing author of The American Dietetic Association's Sports Nutrition: A Cuide for the Professional Working with Active People (4th ed.). Bart De Roover is a former international professional soccer player, having played five games for the national team of Belgium. After his playing career, he served as head coach of several first-division teams, including SV Zulte Waregem and Antwerp RAFC. Bart holds a UEFA Pro coaching license and is involved in the post formation of the Asian Vice-Champions, the Al-Ahli Saudi football club. Balder Berck11za11s, MSc, has a master's degree in both sports sciences and rehabilita- tion sciences from the Free University of Brussels. He has gained experience in soccer through intemships at Manchester City FC, FC Cologne, and Club Brugge K.V. Since July 2012, he has worked mainly as an injury-prevention and end-of-rehabilitation specialist at the Al-Ahli Saudi football club. Before that, he worked for KV Mechelen as a strength and conditioning coach, with specific attention on efficient moving in soccer. Ester Lowette, MSc, has a master's degree in Sports Psychology from The University of Leuven. She has played professional volleyball for over 20 years, winning the European Top Team Cup with Asterix Kieldrecht. Ester played severa} years for the Yellow Tigers (the national team) and has won the Belgian Championship with three different teams. Ante Jaspers, MSc, has master's degrees in Physical Education and Kinesiology and in Rehabilitation Sciences and Physiotherapy from the University of Leuven. He is currently conducting his doctorate about the use of athlete-tracking data in soccer for performance optimization and injury prevention. This project is a cooperation between AZ Alkmaar, the University of Leuven, and TopSportsLab. Before that, he worked as a performance analystwith the KBVB, UEFA and FIFA in supporting the physical preparation of elite soccer referees. John Fitzpatrick, MSc, is an aspiring sports scientist and researcher with a master's degree in strength and conditioning from Teesside University. He is currently a sports science intem at Newcastle United Football Club. His research focuses on the monitoring of recovery and fatigue in soccer players. Pieter Jacobs, MSc, holds a master's degree in sports sciences anda bachelor's degree in rehabilitation sciences from the Vrije Universiteit Brussels. He previously worked as a physiotherapist for Beerschot AC in the Belgian professional league. He works currently at Al-Ahli Saudi football club as Head of Rehabilitation (2012-). TABU: OF CONTENTS 1. TRAINING PRINCIPLES ................................................................................................ 13 1.1 lntroduction ..................................................................................................... 13 1.2 Supercompensation ........................................................................................ 13 1.3 Delayed transmutation .................................................................................... 14 1.4 Cumulative training effect ............................................................................... 14 1.5 Residual effects of training ............................................................................. 14 1.6 lnterference or superposition of training effects ............................................. 15 1.7 Training process and goal setting ................................................................... 15 1.8 Specificity (SpecificAdaptations to lmposed Demands) ................................ 16 1.9 Transfer effect (cross-training) ........................................................................ 16 1.10 lnitial value and diminishing returns ............................................................... 17 1.11 Inter-individual variability ................................................................................ 18 1.12 Nature ar Nurture? .......................................................................................... 18 1.13 Principie of reversibility ................................................................................... 19 1.14 Progression .................................................................................................... 19 1.15 Variation .......................................................................................................... 19 2. TRAINING MODELS ...................................................................................................... 21 2.1 lntroduction ..................................................................................................... 21 2.2 General Adaptation Syndrome (GAS) ........................................................... 22 2.3 The Supercompensation ar one-factor theory ................................................ 23 2.4 Fitness-fatigue model ..................................................................................... 25 2.5 Performance potential model .......................................................................... 31 3. THE PHYSICAL DEMANDS OF ELITE SOCCER MATCH PLAY ................................. 33 3.1 lntroduction .................................................................:.................................. 33 3.2 Activity profile ................................................................................................. 33 3.3 Positional variation ......................................................................................... 34 3.4 Competitive standard ...................................................................................... 35 3.5 Gender Differences ........................................................................................ 36 3.6 Match-to-match variability and stability .......................................................... 37 3.7 Contextual and tactical factors ....................................................................... 37 3.8 Fatigue during match play .............................................................................. 38 4. 5. PHYSICALABILITIES AND THE ROLE OF AEROBIC FITNESS ................................ 73 ;,·~ 5.3 5.4 NUTRITION .................................................................................................................... 43 4. 1 lntroduction ..................................................................................................... 43 4.2 Energy ........................................................................................................... 43 4.3 Substrate Utilization and Macronutrient Needs .............................................. 46 4.4 ATP (adenosine triphosphate) ........................................................................ 53 4.5 Energy systems .............................................................................................. 55 4.6 Macronutrient needs ....................................................................................... 56 4. 7 Eating patterns of soccer players .................................................................. 57 4.8 Glycogen metabolism and nutrient timing for recovery .................................. 58 4.9 Energy Balance and Body Composition ......................................................... 61 4.10 Vitamins, minerais and free radicais ............................................................... 64 4.11 Water and electrolyte balance in soccer players ........................................... 66 4.12 Food supplements .......................................................................................... 69 4.13 Recommendations .......................................................................................... 71 1h ~~~~~~~t~~iiit1~~·::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ;! Aerobic fitness ................................................................................................ 76 Soccer-specific training drills using the continuous principie .......................... 77 6. HIGH·INTENSITY INTERVAL TRAINING (WITH SPECIAL REFERENCE TO SMALL SIDED GAME PLAY) .................................................................................. 83 6.1 lntroduction to High-lntensity lnterval Training (HllT) ..................................... 83 6.2 HllT effects on cardiovascular and muscular adaptations .............................. 85 6.3 Lactate formation during HllT ......................................................................... 85 6.4 Lactate clearance during HllT ........................................................................ 86 6.5 High-intensity interval training versus tow-intensity continuous training ......... 87 6.6 High-intensity lnterval training with ar without the bali .................................... 88 6.7 Small-sided games (SSGs) ............................................................................ 90 6.8 Training Time Distribution ............................................................................... 97 6.9 Soccer-specific training drills .......................................................................... 98 7. SPEED, AGILITY AND QUICKNESS (SAQ) AND REPEATED SPRINT ABILITY (RSA) ............................................................................................... 109 7.1 lntroduction ................................................................................................... 109 7.2 Nature or Nurture ........................................................................................... 11 o 7.3 Blomechanics of Sprinting ............................................................................. 11 O Running technique ......................................................................................... 112 7 .4 7 .5 Speed, agility, quickness and cutting ............................................................. 112 7.6 Definitions ......................................................................................................113 7 .7 Soccer-specific SAQ drills ............................................................................. 113 7.8 Speed ............................................................................................................115 7.9 Tips ................................................................................................................ 117 7.10 Exercises .......................................................................................................118 8. FITNESS TESTING ...................................................................................................... 123 8.1 lntroduction ................................................................................................... 123 8.2 Criteria ......................................................................................................... 124 8.3 Why measure? ............................................................................................. 125 8.4 Test environment .......................................................................................... 126 8.5 The terms "to beH and "as is" ........................................................................ 126 8.6 Tests ............................................................................................................. 127 8.7 Analyzing Testing Results ............................................................................. 145 9. HEART RATE AND GPS MONITORING IN SOCCER ............................................... 149 9.1 lntRoduction ................................................................................................. 149 9.2 Use of heart rate as an indirect measure for oxygen consumption .............. 149 9.3 Resting heart rate (HRr) ............................................................................... 150 9.4 Maximum heart rate (HRmax> ......................................................................... 150 9.5 Lactate threshold .......................................................................................... 150 9.6 Relating the lactate curve to the heart rate ................................................... 153 9.7 lnterpreting HR measurement ...................................................................... 154 9.8 Effect of training on heart rate and lactate accumulation ............................ 155 9.9 Autonomic nervous system .......................................................................... 156 9.10 Examples of heart rate interpretation ........................................................... 159 9.11 GPS Monitoring ............................................................................................ 161 10. TRAINING LOAD MONITORING IN SOCCER ............................................................ 167 10.1 Jntroduction ................................................................................................... 167 10.2 The Training Process .................................................................................... 168 10.3 Internai Load ................................................................................................. 169 10.4 Externai Load ............................................................................................... 177 11. TRAINING CONTINUUM ............................................................................................. 185 11.1 lntroduction ................................................................................................... 185 11.2 Different stages of the training continuum ................................................... 186 11.3 Load and load tolerance ............................................................................... 190 11.4 Overtraining detection scale ......................................................................... 193 11.5 Trainingflaws ................................................................................................ 194 11.6 Relation between load, injuries, fitness and performance ............................ 195 12. FATIGUE ...................................................................................................................... 201 12.1 lntroduction ................................................................................................... 201 12.2 Fatigue in a soccer match ............................................................................ 202 12.3 Underlying mechanisms of fatigue ............................................................... 203 12.4 Effects of fatigue ........................................................................................... 209 12.5 Countering fatigue .........................................................................................211 13. FATIGUE MANAGEMENT ........................................................................................... 217 13.1 tntroduction .................................................................................................. 217 13.2 Performance stabilization ............................................................................. 218 13.3 Fatigue management. ................................................................................... 219 13.4 Recovery strategies ...................................................................................... 220 13.5 Monitoring Fatigue and Recovery in Soccer................................................. 232 13.6 Tapenng ........................................................................................................ 244 14. PERIODIZATION IN SOCCER ..................................................................................... 253 14.1 History of periodization ................................................................................. 253 14.2 Types of periodization ................................................................................... 255 14.3 Season planning ........................................................................................... 255 14.4 Types of periodization ................................................................................... 257 14.5 Periodization models: lntensity and volume ................................................. 258 14.6 Periodization models: Physical abilities ........................................................ 260 14.7 Workload ...................................................................................................... 263 14.8 lntegrated ..................................................................................................... 264 14.9 Types of microcycles .................................................................................... 265 14.11 Periodization in soccer ................................................................................. 265 15. THE TACTICAL PERIODIZATION MODEL (UNDERSTANDING THE GAME'S DEMANDS TO ENHANCE SOCCER PERFORMANCE) ..................... 273 15.1 lntroduction ...................................... , ............................................................ 273 15.2 Tactical Periodization: A new soccer training approach ................................ 274 15.3 Game model ................................................................................................. 276 15.4 Principies of play and game model.. ............................................................. 278 15.5 Tactical Periodization: methodological principies ......................................... 280 16. MACROCYCLE: PRESEASON ................................................................................... 291 16.1 lntroduction ................................................................................................... 291 16.2 Preseason training principies ....................................................................... 292 16.3 Organization of the mesocycle ..................................................................... 296 16.4 Friendly match planning in the preseason stage .......................................... 298 16.5 Organization ofthe preseason training camp ............................................... 300 17. MACROCYCLE: IN-SEASON ...................................................................................... 307 17 .1 lntroduction ................................................................................................... 307 17.2 Duration ofthe mesocycle ............................................................................ 307 17 .3 Organization of the mesocycle ..................................................................... 309 17.4 Three phases ofthe "in-season" mesocycle ................................................ 310 17.5 Remarks .......................................................................................................311 17.6 Individual periodization ................................................................................. 315 17.7 How to implement individual periodization ............................... , ................... 317 18. MICROCYCLE: WEEK PLANNING ............................................................................. 333 18.1 lntroduction ................................................................................................... 333 18.2 Structure of a training session ...................................................................... 333 18.3 Pre-activation ................................................................................................ 334 18.4 Warm up ...................................................................................................... 334 18.5 Central section .............................................................................................. 339 18.6 Progression phase ........................................................................................ 339 18.7 Recovery phase ........................................................................................... 339 18.8 Prevention phase .......................................................................................... 341 19. STRETCHING .............................................................................................................. 343 19.1 lntroduction ................................................................................................... 343 19.2 Types of stretching ....................................................................................... 343 19.3 lncreasing flexibility or preparing the body ................................................... 347 19.4 Use during the training week ........................................................................ 349 20. STRENGTH TRAINING ANO FUNCTIONAL TRAINING ............................................ 351 20.1 lntroduction ................................................................................................... 351 20.2 Physiology of muscle strength ...................................................................... 351 20.3 Strength training and the nervous system .................................... , ............... 353 20.4 Types of strength .......................................................................................... 354 20.5 Types of strength training ............................................................................. 355 20.6 Plyometrics ................................................................................................... 355 20.7 Setting up general strength training programs ............................................ 358 20.8 General strength training exercises .............................................................. 360 20.9 TRX/Suspension Training ............................................................................. 362 20.10 Medicine Bali ................................................................................................ 364 20.11 Functional strength training for the soccer player ........................................ 366 21. INJURY PREVENTION ................................................................................................ 381 21.1 lntroduction ................................................................................................... 381 21.2 Consequences of injuries ............................................................................. 382 21.3 Conceptual model: injury prevention ............................................................ 382 21.4 lntrinsic risk factors ....................................................................................... 385 21.5 Extrinsic risk factors ..................................................................................... 393 21.6 General injury prevention for soccer players ................................................ 397 21.7 lnjury-prevention programs ........................................................................... 403 1 FITN ESS 1N SOCCER Training principies 1 TRAINING PRINCIPLES Werner Helsen, Kenny McMillan, David Tenney, Paul Bradley, Jean-Pierre Meert & Jan Van Winckel 1.1 INTRODUCTION Performance in association football (known as soccer in North-America) depends upon a myriad of aspects, such as technical, tactical, physical and mental parameters. As with other sports, soccer is not a science, but science can assist in improving performance (Stolen et al., 2005) and preventing injury. Training principies are systematic summaries of scientific findings, and these are highly important for the appropriate organization of training sessions and competitions. They are defined as iules and methods that can be used to prepare a player or team for competition in a professional manner. Training principies provide a reliable guidance, and they are therefore important for coaches to understand in order to maximize performance and minimize the chance of failure. 1.2 SUPERCOMPENSATION The Soviet scientist Yakovlev offered probably the first scientifically based explanation of fitness enhancement in 1955. Yakovlev demonstrated the phenomenon of "supercompensation" of muscle and liver glycogen and muscle phosphocreatine stores during recovery from exercise (Yakovlev, 1955). The training principie of supercompensation states that improvements only become evident after a period in which the accumulated fatigue from training can be reduced. A period of relative rest enables the results of training to be better reflected. Son1e important processes occur after the actual training session or match, a períod when the players' bodies are given valuable time to adapt to the training stimuli provided one or hvo days before. Therefore, rest or recovery should be considered an important phase in the overall training process. FITNESS IN SOCCER FITNESS IN SOCCER Training principies Training principies Supercompensation Supercompensation If training is suspended for a given physical ability, the performance levei of that ability will drop. Therefore, after a period of detraining, players will be at a residual levei of performance. For example, at the amateur levei, players often have six to eight weeks off during the summer. The fitness levei remaining after this off-season period is referred to as the residual effect. Long periods of training, complex and multi-component training, and appropriately periodized loads will lead to longer-lasting residual effects (Issurin, 2010). Older and more experienced athletes also have longer-lasting residuais. Some physical abilities, such as strength and aerobic endurance, have longer-lasting residuais when compared with anaerobic parameters. Decreased performance Time Fig. 1.1: The accumulated training /oad (and the corresponding fatigue) results in decreased performance in lhe days immediately after exercise. An adequate recovery results in increased performance through a reduction in fatigue (supercompensation). Residual effects of training 95% .. 90% ~ 85% 1.3 DELAYED TRANSMUTATION This principie holds that in order to realize performance enhancements, specific exercises must be used to transform and maximize the fitness acquired during previous training activities. For example, if a player performs strength training exercises for his or her legs (e.g., squats), there will only be a visible improvement if the player also performs specific exercises (e.g., jumps and sprints). This way, the strength gained is "transmuted" into functional movements. Zatsiorsky (1995) defined delayed transmutation as "the time period needed to transform acquired motor potential into athletic performance." Aspecific work improves the potential for performance, but it \vill not directly improve performance without specialized specific training afterwards (Zatsiorsky and Kraemer, 2006). 1.4 CUMULATIVE TRAINING EFFECT The cumulative effect of long-term training is the primary factor determining a player's physical fitness. The cumulative training effect can be described as "a change in physiological capabilities and level of physical/technical abilities resulting from a long-term athletic preparation" (Issurin, 2008). 1.5 RESIDUAL EFFECTS OF TRAINING One of the primary aims of soccer training is to develop various physical abilities. These physical abilities remain at an elevated levei for a certain period after training ceases. This retention of fitness is explained by the residual training effect, which can be described as "the retention of changes induced by systematic workloads beyond a certain time period after the cessation of training" (Counsilman and Counsilman, 1991). These residual effects have been defined in two ways: in terms of the retention of physical changes following a series of many training sessions (delayed effects) and in terms of the results of a series of many training sessions (accumulative effects) (Hellard et ai., 2005). ~ .5 80% li: Fig. 1.2: A theoretical representation of the residual effects of training. The p/ayer trains four times (once every two days) until day seven. His fitness levei increases through training, but aller eight days of rest, his fitness levei has decreased from 93% (on day 8) to 85% (on day 15). 1.6 INTERFERENCE OR SUPERPOSITION OF TRAINING EFFECTS Players are often exposed to training different physical abilities during the sarne training cycle, particularly for strength and aerobic power. Improvements in strength may be compromised when practiced simultaneously with aerobic power, and this has been referred to as the interference phenomenon (Docherty and Sporer, 2000). The interference effect can be negative or positive depending on the form and sequence of exercise. 1.7 TRAINING PROCESS ANO GOAL SETTING Each training process needs to have a clear training objective. Thls training goal can be determined in both a general way, such as to get into the top five, as well as in a more specific manner, such as to run 3,000 meters in 12 minutes. In their meta-analysis, Kleingeld et al. (2011) showed that specific, difficult goals yield considerably higher group performance when compared with aspecific goals. Moderately difficult and easy goals were also associated with performance benefits relative to nonspecific goals. These findings demonstrate that group goals have a FITNESS IN SOCCER Training principies f ITN ESS 1N SOCCER Training principies robust effect on group performance. Individual goals can also promete group performance, but they should be used with caution in interdependent groups. 1.8 SPECIFICITY (SPECIFIC ADAPTATIONS TO IMPOSED DEMANDS) The principie of specificity is often referred to as the Specific Adaptation to Imposed Demands (SAID) principie. Scientific research has shown training to lead to duration, task and speed specific changes (Rutherford, 1988; Givens, 2010). A sprinter, for example, will improve in speed, through specific training, but not in aerobic endurance. The rule of specificity states that a player has to train in a specific way to acquire a specific adaptation (i.e., specific training results in improvement of that specific movement). This means the biggest physiological changes take place in the structures that were subject to the training stimulus. Magel et al. (1975) provided a good example when they showed how swimmers, after a period of training, achieved an 11.2% improvement in aerobic endurance while swimming. However, when they performed a running test, the improvement in aerobic endurance was shown to be just 1.5%. This finding clearly demonstrates the specificity of training principle, specifically why it is so important that training should mimic the actual demands of the sport as closely as possible. Therefore, training should always be oriented toward the sport itself. The more specific the energy systems used, as well as the actual activity (e.g., biomechanics, position, body coordination, speed, resistance, etc.), the greater the chance that specific improvements will occur. their endurance levels after a period of deep-water running, which involves running movements in deep water while the athlete wears a flotation belt. This method is therefore not only useful during periods of injury, but it can also act perfectly as an altemative training or recovery workout following a match. Reilly et al. (2003) concluded that aerobic performance is maintained by deep-water running for up to six weeks in trained endurance athletes, while sedentary individuais showed greater improvements in their maximal oxygen uptake V0 2mnx than athletes. There is also limited evidence showing improvements in anaerobic measures and upperbody strength in individuais who engaged in deep-water running. The research literature clearly shows that any form of specific training produces more effective results than cross-training. However~ specific types of training are sometimes not possible (e.g., because of injury or overtraining). On these occasions, cross-training is an ideal substitute to help preserve as much fitness as possible. Different modes of aerobic training (e.g., aqua-jogging, swimming, cycling or ro\ving) can be used to obtain positive adaptation phenomena or training effects. 1.10 INITIAL VALUEAND DIMINISHING RETURNS The principie of initial value and diminishing returns implies that progress will be greater for individuais with a lower baseline level than those who have already reached a high level of performance. When commencing strength training, results are quickly evident in the initial phase. However, experienced players need to train more often and with greater intensity to see the sarne progress after a few weeks. Therefore, it is important for training to be adapted and evaluated relatively quickly at the beginning of the training program. 1.9 TRANSFER EFFECT (CROSS-TRAINING) ln contrast to the rule of specificity, a transfer effect can be obtained if correct planning is carried out. For example, research has shown athletes are able to maintain Law of diminishing returns 100 90 '° ] '° 60 ,,, ! 1 4050 i / / 30 '° 10 o / / / Ci Tim~ ln 1mlnlnc Fig. 1.3: When unfit players begin a training program, their physical fitness leveis increase rapidfy. When they become fitter and approach their genetic /imits, lhe law of diminishing returns becomes apparent. ln conclusion, good progress can be observed for a soccer player during the initial phase of a program. However, as the player's fitness and stamina increases over time, the less pronounced this progress will be. FITNESS IN SOCCER Training principies FITNESS IN SOCCER Training principies 1.11 INTER-INDIVIDUAL VARIABILITY 1.13 PRINCIPLE OF REVERSIBILITY Adaptation to training is known to be a highly individual phenomenon (Avalos et al., 2003). The improvement in response to a training stimulus varies from person to person not only because of differences in "nature" (genetic predisposition) but also because of "nurture" such as pre-training condition; gender, age and ethnicity; health, diet and sleep; environmental factors such as heat, cold, and humidity; and of course motivation. Players respond to the sarne training stimulus in different ways, with some players adapting better and quicker to a particular stirnulus than others. Therefore, each player can be categorized as a low, moderate or high responder. Hohman (1988) examined the training variations of the West German water polo team for the Olympic Games in Seoul, specifically the relationship between the training load and competitive performance. Two different types of athletes emerged: those that responded quickly to training stimuli and those that did not respond so quickly. Inter-individual variability also depends on the type of exercise. For example, some players will progress more in terms of speed development, while others will improve more rapidly in the area of aerobic endurance. Training responses can differ to a huge extent, with the level and speed of progress varying widely between players. Four weeks of preparation may be sufficient for some players, while others may need up to eight weeks. The impact of h·aining also depends in part on the athlete's physical maturity. Training is less effective before puberty than it is afterwards. Detraining is defined as the partial or complete loss of training-induced adaptations in response to either the cessation of training or a substantial decrease in the training load (Mujika and Padilla, 2003). We all know the adage of "Use it or lose it." Adaptations resulting from training disappear when training is discontinued. 1.14 PROGRESSION A particular training load needs to be increased systematically and progressively over time, with adequate time being given to reach the training objectives. A sudden increase in training load can lead to an imbalance between load and load tolerance, •vhich subsequently increases the likelihood of injury. 1.12 NATURE OR NURTURE? Is a top soccer player born as such, or is that player the result of years of hard training? This is a question that has preoccupied scientists for decades. Is it nature (i.e., son1eone's genetic predisposition) or is it nurture (i.e., the amount of training) that makes someone a top soccer player? The predominant factor that determines an individual's response to exercise training is genetic predisposition, because players \vill respond to exercise training differently. Some individuals respond better to endurance-type training, •vhereas others respond to shorter activities biased more to power and strength. Many scientific papers have examined the genetic response to exercise training, and Bouchard et al. (1992) concluded that heredity can account for 25-50% of the variance in V02 m.ix values. Costill and Wilmore (1998) reported improvements of 0-43% when a group of subjects followed identical endurance training programs for up to 12 months. Indeed, it is commonly said, "The best \vay to become an elite athlete or football player is to be selective when choosing your parents!" lt should not be forgotten, of course, that the amount (quantity) and quality of training will determine whether you fulfil your genetic potential. ln conclusion, talent has to be first identified. Specific training programs are then needed to develop and fulfil a soccer player's genetic potential. 1.15 VARIATION Training requires a varied approach where all the basic physical abilities can be trained. A varied program needs to be established \.Vithout losing sight of the other principies. Variety in the exercises perforn1ed ensures the greatest progress and n1inünizes the chance of injury, because the monotony of traíning load represents a significant risk factor for injuries. Monotony is a measure of the variability over training sessions, and it is calculated by dividing the \veekly training load by the standard deviation of that load for the \Veek (Poster, 1998). Enhancement of performance is achieved by systen1atically n1aking changes in training parameters, with volume and intensity being the most general training characteristics. Barre (1982) suggests that programs where athletes are subjected to a steady, regular load should be díscouraged. Strain is the product of the \veekly training load and n1onotony (Foste1~ 1998). Foster (1998) showed that high training load and high training monotony are both factors relating to negative adaptations to training. Furthermore, Putlur et al. (2004) reported a significant relationship bet\veen índices of training, such as strain and monotony, \Vith the incidence of illness. Finally, recent research demonstrated that the \Veekly duration, training load, monotony and strain over the preceding week were significantly higher for players with a traumatic injury \Vhen compared with healthy players. (Brink et al., 2010). 201 FITNESS IN SOCCER Traíníng models FITNESS IN SOCCER Training principies SUMMARY It is important for a soccer coach to have an understanding and appreciation of training principies. Coaches should be aware that not all soccer players will adapt the sarne way to training sessions - the training load may be too much for one player, predisposing him to injury, but too little for another player, perhaps causing a detraining effect. Soccer training should be specific to the needs of the soccer player and should vary from session to session, with a clear and safe progression to induce positive training adaptations and avoid the accumulation of fatigue, illness and injuries. TRAINING MODELS Jan Van Winckel, David Tenney, Kenny McMillan, Paul Bradley REFERENCES AvaJoe., M., Hcllnrd, P. and Chatard, J,C., 200J. Moddini; lhe tr.1íning·porformani::c rdat10n"h1p uoing a mixcd modd in chtc ~wimmers. Mcd. Sci. Sports Excrc., 35, pp.1!3$-846. Douchord, e., Dionnc·, f.T., Simoncau, J.A. and lloulny, M.R. (1992). Gcnctic; o( acrobic nnd anncrobic pcrforrnanC\.'S. Excrcioc and Sport Sacnres Rcvkws, 20, pp. 27·58. . . .· Brink, M.S., Vit<S<:hcr, C., A"'nds, S., Zwcrvcr. ]., Po8t, W.J. and Lcmmink, K.AP.M., 2010. Monilormr, Sl"''" and "'covcry: ncw 1m1ght,; for thc P"'vcnlion of injuries and illncfiocr. ln clilc youth e.ocrer plnycro. British Joumal OfSports Medicine, 44(11), pp.SCl9.Jll5, Coun:;ilman, ll. E. and Coun,;ilmnn, )., 1991. Thc n»i<lunl dfccl~ of trnining. Swimmmg RcS<:arch, ·!. Dodicrly, D. nnd Spo,..,r, ll., WOO. A propO$Cd modcl for cxamirüng thc inlcrfr,..,ncc phcnomcnon bctwccn concummt ncrob1c and strcngth trnining. Sports Medicine, 30(6), p.385·39·1. . . . Fmtcr, C., 1993. Monitoring training in athletc'S with "'forcnre to ()Vcrtraimnr; syndromc. Mcdmnc and ~c1cncc m sports and cxcrcisc, 30(7),p 116-1 Hcllard, l'., Av,11m, M., Mille! G., L.1co,;le L. and Q,,1tnrd,).C., 2005. Modchng the ,..,s;duol dfoct> and thrcnhnld oaluratrnn of lrnining: A cascotudy ()f Olympic swlmmcrn. j, Strcngth Cond. Reo, 19(1}, pp.67-75. Hohmaon, A., 1992. Annly,.is of dclaycd trnining dfccl!; in th~ prcp.ua\ion of thc Wcr.t·Gcrrnnn w.1lcr polo lc.1m for thc Olympic games 1983. ln: D. l-.facL1ren, T. Rcilly and 1\. Lccs, Eds., 1992. Sw1mmi11g scicncc V!. London: Eb. FSpon J,,,;urin, V., 21)0$. Prindplco nnd b.>,.iOJ of advan«:d troining of athlctcs. Mur.kegon (MI): Ullimale ;\thlclesC?nrepl5 Publbher. Jr- 5urin, V., 2010. New horizo"'' lor lhe mclhodology and physiology ()f !r.1imng pcnod1zalmn. Sportc. mcdkme, ·\0(3), pp.189·2G6. . Klcingcld, A., van Micdo, H. and ,\,..,nds, L., 2011. The dfect oi gonl ocllinB on group pcrformnnre: A mct.1·.>nnlyr-10. )ou mal ()f r\pphed l'sychology, %(6), p.1289. Mngel, j,R., foglio, G.f., McArdle, W.D., Gulin, B., l'cchnr, G.S. ,1nd Katch, F.i., 1975. Spcdficily of ,;wim lr,1ining on maximum oxygen uplakc. joumõl oi Applicd l'hyr.i()logy, 35(1), pp.151·155. . . . . . . Mujib, 1. and Pndilln S., 2003. Physiolo;:;icnl ""d P"rform;mcc con.<cqucni:l!fo of !ramrn;:; c:"'""t1on m <;.lhlctcs: dclrornrng. ln: W.R. Frontcra, cd. 2003. Rchabihtnlioo ofSporb !n1un...,;: Scicnt1fic Bnsis. Maldcn, MA: Blackwcll Socncc. pp.l\t-143. . , . Putlur, !'., fostcr, C., Miokowski, j.r\., Kanc, 1'1.K., Uur!on, S.E., Schcctt, T.P. and McGuigan, M.lt, 200-1. Altcrnlmn of1mmunc lunction m womcn collcgiate wcrer playcro and collc;:;c studcnts. Joumal of SpMl> Sdencc and Medicine, 3, pp.23-1-243. Rcilly, T., Dowzcr, N. and Cnble, N. T., 2003. Thc physiology of dccp·walcr mnning. )ou mal ofSports Socncc, 21(12), pp.959-972. Rutherford, O. M., 19SS. Muscul,1rçoordinntion and strcngth lr.1inin!). Sp()r!!; Medicine, 5(3), pp.196-202. S.11c, D. and MacDougall, D .. 1981. Spccifidly in strcngth tr.1ining; a rcview for thc coaclt and athletc. Cnnndian joumal oi npplicd spurt ~denccs, 6(2), p.87. , , . Wilmorc and Cost1!1, 2005. Physiology oi Sport and Excrcisc: 3rd Edit1on. Chnmpaign. lL: Human Kmcl1o;. Y,1kovlc•~ N.N., 1955. Survcy on ~pari biochcmbtry. Mosww: FiS. Zlt~ioroky, V.M. aod Krncmcr, W.j., 2006. Scicnre and prncliceof strcngth .lrnining. Champ~ii;n: Hunrnn KincliC!>. Z.1l!>iorsky, V, M .. 1995. Sdcncc and prncticc oi strcnglh trnming. Champ.11gn, 11.: Humõn KmcliC!>. e. 2.1 INTRODUCTION Training models are theoretical models that enable coaches to understand the training process and its impact on physical performance. These models can then be used as a framework to design training programs. Most coaches are aware of the supercompensation model (the one-factor model), which clearly explains why performance improves after a period of rest. Unfortunately, this model is incomplete, and it has been replaced over the last few decades by the fitness-fatigue model (the two-factor model). This model provides coaches with additional insight, enabling them to make more accurate predictions about the impacts of various training regimes. This allows the training Ioads of individual athletes to be anticipated and ultimately modified to suit their requirements. Clearly. the primary aim of any soccer training program is to ensure the players are in peak fitness on match day, so it is therefore important to also consider fatigue effects resulting from training and its eventual impact on match fitness. ln recent years, a considerable amount of research has been published on the effect of different training models. A brief summary of this research is provided below, ranging from the original model from Hans Selye to the supercompensation model (the one-factor model) and the fitness-fatigue model (the two-factor model). FITNESS IN SOCCER FITNESS IN SOCCER Training models Training models 2.2 GENERALADAPTATION SYNDROME (GAS) 2.2.1 Hans Selye Dr. Hans Selye, an endocrinologist, was one of the first scientists to describe the response of the human body to any kind of stress. ln 1938, he proposed the General Adaptation Syndrome theory (GAS), which involved two major systems of the body: the nervous system and the endocrine system. ln 1946, he defined GAS as the sum of all the non-specific, systematic reactions of the body that ensue from continued exposure to stress. 1. The alarm phase The first stage of GAS, the alarm reaction, is the immediate reaction to a stressar. In the initial phase of stress, humans exhibit a "fight or flight" response that prepares the body for action. The alarm phase is divided into two further phases: the shock phase and the antislwck phase. • ln the shock phase, the resistance to the stressar drops temporarily below the normal range (baseline). • The anti-shock phase is when the threat ar stressar is identified or realized. The body then starts to respond and is now in a state of alarm. 2. Resistance The resistance phase depends on the athlete's levei and genetic potential. If stress continues during this phase, the body adapts to the stressors it is exposed to. According to Dr. Selye, this adaptation begins after 48 hours and within a period of four weeks. 3. Recovery or exhaustion The recovery stage follows once the systern's compensation mechanisms have successfully overcome the stressar effect. Alternatively, exhaustion may be the third stage in the GAS model, and at this point, all of the body's resources are ultimately depleted, leaving it incapable of maintaining normal function. General adaptation syndrome (GAS) -·--·- -·--··-·----neslstance to sfreSf"füiforeexnaUst1on-s·etsin--- Sij°: 'í" '.: : :_~=: : _: : : :_:=:::=::::::j::::::-:7":--= ==-====-~:~~==-:~~~:-~-= ~~~--~--!---------------+-/------------ ---------------------- !-'---·-·---.----------·-- --1----------------V------------- -- - --------------- --!-- ----"-<------------ - -- --+--------+1------------------r---"ç------------------- -r~=- -+- !____ _ -=====r-- ---;=------ -~ Basehne_ _ _ _ _ _ _ _ ,_ - - - - - - i_ _ __ Shock___________An~hock_I _______ ! ?hase 1: Alarm phase ______,_ ?hase 2: Resistance (cope wíth stressar) Fig. 2. 1: General adaptation syndrome Phase 3: Exhaustion 2.2.2 Use of lhe GAS model in sport Prokop and Rõssner (1959) were one of the first to use Selye's concept of GAS to explain the concept of periodically decreasing the amount of training. Forbes Carlile (1961) applied Selye's theory to sport in a series of Track Technique articles narned The Athlete and Adaptation to Stress. He suggested using the GAS modelas a theoretical foundation. Indeed, Hans Selye's GAS can serve as a theoretical frame\VOrk for adaptation to training, since training can be regarded as a type of stress. Matvejev (1964), however, criticized the use of the GAS model to explain periodization, postulating that the GAS theory was based on pathological material. Coaches and scientists should be wary of rigidly translating Selye's biochemical model to sport, because performance does not only result from the storage or release of biochernical substances. 2.3 THE SUPERCOMPENSATION OR ONE-FACTOR THEORY The terms supercompensation, superadaptation and adaptive reconstruction (Russian science) are widely used to explain the results of optirnal training and the effect of subsequent recovery. Overload training is a method of stressing an athlete ata higher level than formerly tolerated \Vith the aim of stimulating adaptation and thus supercompensation (Steinacker et al., 2002). The supercornpensation effect that can occur after stressing an athlete is a relationship between \Vork and recovery that leads to horneostatic adaptations to higher levels (Bompa and Haff, 2009). The training phenomenon known as the supercompensation effect was probably first described by Folbrot in 1941. In the 1950s, the Russian biochemist Yakovlev (1955) demonstrated supercompensation of muscle and liver glycogen and muscle phosphocreatine during post-exercise recovery. Yakovlev (1967) classified supercompensation as a four-step process: Phase 1: Fatigue after training. There is a predictable drop in performance due to the stress induced by training (1 to 2 hours). Phase 2: Compensation (rest) phase. Energy stores and performance return to the baseline (24 to 48 hours). Phase 3: Supercompensation of performance (36 to 72 hours). Phase 4: A decrease in the physiological benefits, the so-called detraining phenomenon, obtained during the supercompensation phase. This occurs when the athlete does not apply another stimulus within an optimal period of time (i.e., during the supercompensation phase) (3 to 7 days). FITNESS IN SOCCER FITNESS IN SOCCER Training models Training models Training j j Lo ad ---r·: ' : , -----1-/ ir.ecovervi :: - ---~:--. \Recoverv: Lo a d ' : Recovery: lo ad Lo ad Fig. 2.2: Supercompensation or one4actor theory A sufficient training load results in a temporary decrease in performance. With an optimal recovery, this stress eventually leads to a greater performance than the initial level. This next training load might be higher because of increased fitness leveis and a consequently higher levei of load tolerance. The soccer players' performance levei will increase as a result. Ho"\vever, if too much time elapses betvveen tvvo training sessions, performance does not increase and can even decrease (detraining). -----------~---, ' ' ' ., ' :' . '' '' '' ' .' '' ' -----~- .. : . - '' Fig. 2.3: Excessive time between traininfl /oads. sarne day. This is of course perfectly possible, and it will improve performance over the long term when applied properly. So, is the supercompensation model incorrect? This model can be interpreted as the consequence of accumulated load followed by a rest period that allows supercompensation to take full effect. Each physical ability-such as speed, endurance, strength, and so on-has its own response and recovery rates and supercompensation curve. The replenishment of ATP and CP requires only a few seconds to a few minutes to return to baseline leveis, while the reloading of glycogen in soccer can take up to 48 hours. One of the consequences of supercompensation is an enhanced load tolerance when recovery is adequate and the new load is timed properly. 2.4 FITNESS-FATIGUE MODEL The GAS ar supercompensation model offers a theoretical framework for the process of adaptation that is easy to understand. Both models, however, have their limitations, and they cannot be used to predict future performance. The fitness-fatigue model was first conceptualized by Banister (1975). This model states that a training stimulus leads to two internai effects on the body: fatigue (a negative effect) and fitness (a positive effect). The fitness-fatigue model, also known as the two-factor model, associates the superimposed effects of the fitness and fatigue processes. The principie holds that the fitness effect of training is relatively small but long lasting, while the fatigue effect of training is shorter in duration but greater in magnitude. ln this model, the two aftereffects of training fitness and fatigue both influence the preparedness of the player. Preparedness, unlike fitness, is influenced by acute changes in the subject. Traínlng --.---lll>i + FITNESS Fig. 2.4: lnadequate recovery periods This is where the interval between the training stimuli is too short, so recovery is not complete. The body is still recovering when the next training stimulus is encountered. According to this model, performance will decrease. However, this model does have its limitations. For example, a coach would need to wait until a player is fully recovered before providing a new training stimulus. ln reality, however, a new training stimulus can be imposed on players before they are fully recovered, such as having two training sessions on the FATIGUE Fig. 2.5: The fitness-fatigue mode/. The athlete (player) is viewed as a system with training impulse as input and performance as output. FITNESS IN SDCCER FITNESS IN SOCCER Training models Trainíng models A training stimulus results in two effects. There is a "fitness effect," which is relatively small and disappears slowly, anda "fatigue effect," which is greater in magnitude but may also dissipate quickly. The extent to which fatigue disappears depends on the individual, but it may also be influenced by the recovery strategies employed. Preparedness is the combination of fitness and fatigue. ' .............. ~ Fitness --- --- --- ..........··· 1 2 •"'e •"'e "C õ > .!! "" ~ , "C "C o :E "'• •• -4 •"' ••e "C "C -3 •"' "C ,~ ~ 1- ~ -2 :g•"' -1 G "' "E• "C •"' ,e ~ "' "' 100 o "' "- Training load 20 80 65 30 10 o Fitncss effect 0.8 -0.48 -0.24 0.64 0.48 -0.24 -0.4 -0.48 80.8 80.32 80.08 80.72 81.2 80.96 80.56 80.08 200 -120 -70 160 130 -80 -100 120 Fitness leve! ............................._.....,.:.::-.::·::::::·:.:::::·:.:·:::·:.:·::··.:::·············· G 80 Fatigue effect "' Fatigue lcvel 25 225 105 35 195 325 245 145 25 Preparedness 55 -144.2 -24.68 45.08 -114.28 -243.8 -164.04 -64.44 55.08 Tabfe 2.1: A theoretica/ examp/e of how lhe effects (fitness and fatigue) of training load can be estimated. Detraining Fitness leveis are high but are masked due to accumulated fatigue Preparedness is optmized as fitness leveis are stil! high but fatigue has dissipated Fig 2.6: The fitness-fatigue model This model can be explained by using the following theoretical example: We assume a normal training stimulus with a value of 6,300 arbitary units (AU) (90 minutes training x 70% = 90 x 70 = 6,300 AU). This creates a fatigue effect of 200 and a fitness effect of 0.8. (Note that these are abstract figures to illustrate the impact of a training stimulus). This fitness and fatigue effect is in addition to the existing fitness levei of 80 and fatigue level of 25. This results in a fitness level of 80.8, which is the existing fitness of 80 plus the fitness of 0.8 acquired through the match, and a fatigue of 225 (200 + 25). The preparedness is the difference betvveen fitness and fatigue. After the match, this is then -144.2 (fitness -fatigue= preparedness). Although the fitness level increased dueto the load of the match, the preparedness dropped immediately following the match. The increased level of fatigue masks the increase in fitness. It is only after an adequate recovery and a reduction training load that the increases fitness levels can be seen. Match day: Before the match, the player displays hardly any fatigue (25). He or she therefore has the necessary freshness (preparedness levei of 55) to play in the match. After playing the match (training load = 100), the player improves in terms of fitness due to the game, but fatigue also increases, causing the preparedness to immediately diminish to -144.2 following the match. Match day + 1: ln this example, the day follo\ving the match is a complete rest day (training load = O). The player's fitness level drops slightly but not to the extent that fatigue drops, meaning the player's preparedness level starts to rise again. Depending on his or her physical ability (i.e., speed, endurance, etc.), the player's performance level only returns to its pre-match level after 48 to 72 hours. Match day + 2: Two days after the match, a light training session is organized (active recovery: training load = 20), resulting in fatigue and fitness continuing to decrease. The preparedness leve}, however, rises to approximately 80% of its prematch leveL Match day + 3-4: During the third and fourth days after the match, loading strategies to induce overload are imposed. Fatigue can be increased over these two days (accumulated fatigue) to induce acute fatigue, disrupt homeostasis and elicit performance enhancement. After these two days, a player will consequently have improved fitness, but his or her preparedness will decrease beca use of accun1ulated fatigue. Match day + 5-6: During these two days, tapering strategies are imposed. The training load is reduced through decreased training volume in particular. 2s FITNESS IN SOCCER I Training models FITNESS IN SOCCER Training models Preparedness Training load distribution 1l ..9 .se 100 ., 20 120 ~ 80 .~ 'º ~ 40 " o •º" of Days ofthe week Fig. 2. 7: Training load distribution. Fitness status Fig. 2.10: The evolution of preparedness over the lrainlng week. Preparedness drops alter the match because of the fitness levei being masked by accumulated fatigue. Tapering stralegies are used at the end of the week, causing the fatigue to dissipate and performance to increase again. One of the n1ost important extensions to this model is the "specificity of fatigue." This rneans each physical ability has its own fatigue and fitness curve. For exarnple, \vhen training endurance, aerobic fitness will increase, but there will be a lirnited (or even negative) effect on strength. ·-~~~-:;;~:"""~·?::·::::::.~:· Specific fitness effect Days of the week ., ,.<___Fig. 2.8: An example of the evolution of fitness during the training week. Fitness increases slighfly during the week. '.'. / Fatigue status /; 'ºº ·!-------------- !1 ft / ' , & 100 +---- 1 Specífic fitness effect ..,.,--- .~--- ---------:::.-_-,, " ,,"" Specífic fatigue effect "";>:,, Generill Prepilredness '1t- /I fI ·!---·!---- / / 350 ~--------~-----~---~~] 250 -; 200 ~ 150 General htness '''· ' '~ ... .:.~-. / 'lt-" ,~ Specífic fatigue effect Generill fatigue ;;, ,' _ so01-_ ·1--- , F1tness increases but masked dueto ~ccumulated fatlgul'..' 01'..'trnining Preparedn!.'SS Is optimízed as fitness levei is still h!gh but fatigue has dissipated Days ofthe week Fig. 2.9: The course of accumulated fatigue during a training week. Fatigue increases contlnuously dun'ng a training week (accumulated fatigue). This especia/fy occurs during the training days of Wednesday and Thursday, when training can be intense and lhe /oad can be high. lt is therefore important to incorporate rest ora significantly reduced /oad (reduce duration of training) before a game (tapering) to maximize lhe fitness effect ofthe lraining week (defayed transformalion of gains). Fig. 2. 11: A modified fitness~fatigue mo dei representing multiple types of fitness and fatigue aftereffects. The original model presented the effects of training as one fitness cuNe and one fatigue cuNe. ln reality, however, there are specific training effects. Forexampfe, sprint lraining induces different effects when compared to aerobic fitness training. Consequently, there appears to be specific windows for lhe adaptafion for each physical ability (Gamb/e, 2012). Particular acute adaptive responses are described as being restricted and specific to lhe systems used in the training stimu/us, rather than a generic response (Chiu and Barnes, 2003). l 29 FITNESS IN SOCCER Training models FITNESS IN SOCCER Training models Su Mo Tu We Th Fr Sa .... -· -·-. -· -·-. -·-. Su Fítness levei 2.5 PERFORMANCE POTENTIAL MODEL The fitness-fatigue rnodel has been recently criticized for its inability to predict performance with accuracy, as well as for the fact that the model is poorly corroborated by physiological mechanisrns (Hellard et al., 2006). A different approach was taken by Perl (2001) with the development of the Performance-Potential (PerPot) meta-model. This model studies the non-linear interaction between load and performance and is based on the antagonistic concept of PerPot. Load Rate (LR) ~ 1 F11tigue ofter-effect Training loJd Overflow Response-Potential (RP) Fitness levei - - - - • Preparedness levei --- F11tlgue leve! Fig. 2.12: Fitness-fatigue effects during a microcycfe in soccer. The figure depicts the (accumulated) fitness and fatigue curves, the specific fitness and fatigue aftereffects of training, and the resufting preparedness curve. + Performance-Potentíal (PP) Fig. 2. 13: Modified and simpfified representation of the Petformance-Potentia! meta-mode/ ln this meta-model, the output (performance potential) is influenced by the input load (training). This input load is controlled by two interna} buffer potentials: the strain potential and the response potential. Both potentials are influenced equally by training, and they affect performance in an antagonistic \vay. After certain delays, the response potential raises the performance potential and the strain potential reduces the performance potential. The relationship between these delays specifies the performance profile. An overflow pathway \Vas added to the basic structure (Perl, 2004) to allO\V a breakdo\vn if the load over a period of titne becomes too high. This overflo\V pathway reduces the performance potential with a small delay. As was described in the fitness-fatigue model, the PerPot paran1eters need to be adapted individually based on empirical data. ln contrast to the fitness-fatígue model, only a few scientific studies has been conducted to validate PerPot, although Hellard et al. (2006) postulate that the PerPot method appears to be conceptually very rich. FITNESS IN SOCCER FITNESS IN SOCCER The physicaf demands of elite soccer match p/ay Training models SUMMARY Training models help coaches to understand the training process and can be used to design training programs. The supercompensation model helped explain why performance improves after a period of rest, but this model has been replaced over the last few decades by the more complete fitness~fatigue model. This model enables coaches to make more accurate predictions about the impacts of their training regimes. Preparedness is the combination of fitness and fatigue, and the main aim of the soccer training program is to ensure the players are physically fit and fatigue free on game day, so that they can cope with the imposed physical demands of 90 minutes of competitive play. The physiological demands of soccer are discussed in detail in the next chapter. THE PHYSICAL DEMANDS OF ELITE SOCCER MATCH PLAY Paul Bradley 3.1 INTRODUCTION Time-motion analysis is a valuable data-collection technique used to quantify the match performances of elite soccer players (Carling et al., 2008). Interest has substantially grown in this area over the last decade, because it enables sports scientists to identify the current demands placed on players in competition and apply the data to training and testing protocols (Bradley et al., 2011). This has been driven, above all, by the availability of new technologies that help further our knowledge of trai9-ing and testing modes to optimize soccer performance (Castellano et al., 2011). One such technology regularly used in elite soccer involves semi-automated monitoring through video tracking, using systems from match analysis companies, such as Prozone® and Amisco®, to simultaneously track the movements of ali players, the referee and the ball. This chapter therefore aims to detail the factors that impact the physical demands of modem elite soccer \vith special reference to position, gender, and standard, as well as contextual influences and fatigue. REFERENCES Budgclt, R. \<)')S. fíltiguc and undcrpcrfonnancc in a!hlclcs: thc ovcrlrainini; ~.y~dromc. llr J Sporl,; Mcd, 32(2), pp.107':"1rn. llompo, T.O., and Hafi, G., 200\I. l'criodiiat1on: thcory om! mcthodology o! trmmng. 5th cd., Champo1gn, !L: Humnn Kmct1c::, pA24. C.nhlc, E, 1961, Thc Athlclc ,1nd Adaptalion loStrc!ls. Track Tcchniquc, 5, pp.1%-15$ Car!M, F., 1961. ScicnlificTrends in Trninini; thc Sportfiman. Tmck Tcclmiquc, 3, pp.&l·SS Chiu, LZ.F. nnd 1mcs, j.L, 2003. Thc Fitncno--Fntiguc Modcl Rcvisilcd - !mplications for Plannmg Slrnrt- nnd Long-Tcrm Training. Strrngth nnd Condilioning )ou mal, 25(6), pp.·12·51 Folbrot, 19·11. ln: M C. Siff and Y.V. Vcrkhoohansky (1999). Suf"'rtrnming. (·llh cd.). Dcnvcr, CO, p.Sl G,1mblc, !'., 2012. Strength and Cond1tionini; lor Tcam Sporls Sport·Sf"'dÍlc Phy~ical l'wpamt1on for High l'crfonn.1nc.', Scrond Edition. .. Abingdon: Routkgdc. . . . MalWJCV, L., 1964. Da 5 problcm der pcriodioicruni; dc1; :;portlichm trniníng' [Thc problcm of thc f"'ru.id1zatJon m sporls tr,10nmg]. Mo,cow. Mohr, M., Krustrup, !', and Bang,bo,J_., 2005. Fatiguem soccc" a brid "'vicw, Joum,1! of sporl~ ocicnce•, 23(6). pp.S?J._599 Pfdlfrr. M., 2003. Mode!ing thc J<clahonr.lup botwccn Traming and l'crforman"-~A Companson of Two Antagomslic Conc.:pts. Jnt. J. Comp. Sd. Sport, 7(2). _ . _ . Perl,)., 2001. Pcrl'ol: a Mctomo<le! for simulahon oflo.1d pcrfonn,1nc.: inlcrachon. Elcclromc)oumol ofSportScicnc.:, 2. Perl, J., 200·1. 1\ neural nctwork upproach to movcmcnt p.1t1cm analyoif.. Human Mo:·cmcnt Sc1cn.cc, 23, pp.60.5-620. Perl,) .. 2005. DynomicSimulolionof Performance Dcvc!opmcnl: l'"'diction nnd Opl1mal Schcduhng. tntcmahonaljouma! ofComputcr Scicnc.: in Sport, 4(2), pp.28·37 Perl, J., 2006. Jntcrnction in Games; QualitMivc ,\noly~is by Mc.im; oi th" Load-Pcrforman"-~Mctamo<ld Pcrl'ot. lnlcmationa!joumul of Computcr Scicnc.: inSpor!, 5(2). pp.38-11. _ _ Prokop, L and Rl>ssncr, F., 1959. Erfolg im Spo'.t:Thconc und l'r.1xis der L<.'i"l"ngsc.tcigcrung. H.S. Füdmgcr. Sclyc H., 1938. Exf"'rimcntal Evidcn,,.,Supportmg thc Conccption of"Adapt,1lion Encrgy." Am) Phy~iol, August.31123,(3), pp.158-:65. Sc!yc H., 19·l6.111cGcncrnlAdaptalion Syndrnmc and lhe Dbca!;cs of Adaptation. Thc joumolofChmml Endocnnology & Mctabolrnm, frbruary 16(2), pp.117-230. . . . , Stcinackcr, J.M. and Lchm,1nn, M., 2002. Chnlcal find 1 ng~ and mcchonism:; of olwt'5 and n:covery m n1hlcws. ln: Kcllmann, M., cd. 2002, Enhandng "'rovcry; prcvcnting undcrl"'rformano.> in alhlctcs. Champ,1ign, ll: Human Kinctics, pp.103-118. Yakovlcv N .. 1967. Sporlr. biochcmistry. Leipzig' Dcutche Hochr.chulc íür Kõrp<'kultur. n. 3.2 ACTIVITY PROFILE The activity profile of soccer is intermittent, with players regularly alternating between brief bouts of high-intensity exercise and longer periods of low-intensity exercise (Rampinini et al., 2007). During elite matches, players cover 9-14 km of distance in total, with high-intensity exercise accounting for 1-3 km of this (Bangsbo et al., 1991; Bradley et al., 2009; Di Salvo et al., 2009; Mohr et al., 2003). This results in an average intensity of approximately 70% of maximal oxygen uptake and elicits blood lactate concentrations of 4-6 mmol/L (Mohr et al., 2005). However, expressing match intensity as an average value disguises the unique physiological stress induced during intense periods (Glaister, 2005). During these periods, heart rate (HR) can exceed 95% of its maximum, and peak blood lactate concentrations can reach 8-12 mmol/L (Ali and Farrelly, 1991; Bangsbo, 1994). During a typical English Premier League match, players stand still for 6% of the total time. Low-intensity activity represents 85% of the total time, which comprises 59% walking and 26% jogging. High-intensity activity represents 9% of the total time, which is broken down further into 6% running, 2% high-speed running, and 1% sprinting (Figure 3.1). 34 FITNESS IN SOCCER 1 FITNESS IN SOCCER The physica/ demands of elite soccer match play The physical demands of elite soccer match p/ay 3.3 POSITIONAL VARIATION The large differences observed between various playing positions for the energetic and physical performance characteristics of elite players is one of the most robust findings from time-motion analysis studies (Di Salvo et al., 2009; Bradley et al., 2009; Rampinini et al., 2007). When comparing the five most-common positions, it is clear that central and wide midfielders cover more total distance than any other position, with the wide midfielders and fullbacks also displaying superior high-intensity activity profiles (Bradley et al., 2009). The attackers and central defenders consistently sho\v the lo..vest physical performances during a game (Figure 3.2). These findings have implications for developing position-specific training drills that mimic the characteristics of each position by taking into consideration the unique tactical, technical and physical demands of various positions in the team (Di Salvo et al., 2007). Thus, separate dril1s for each position can be constructed, either as a rehabilitation tool or for isolated drills. However, conditioning simulation drills in which all positions are worked together in unison with game- and position-specific ball work are much more fruitful in the applied environment due to player enjoyment and coach acceptance. 4000 111 lstHalf 02ndHalf 3500 g ~Total 3000 m e 2500 e ê 2 " ;;; 2000 e ~ 1500 "' 1000 ~ ~ 500 o Central Defenders Fui! Backs Central Mdfie!ders Wide Mdfielders AUackers Playlng Positlon 100% 80% ~ ~ 1- 60% 40% '' '' ' ' ' '' ' ' ' '' ' ' '' '' '' '' '' '' '' '' '' '' Fig. 3.2: Pbsitional variation in high·intensity running profiles during Eng/ish Premiar League '' '' matches (Data from Bradley et ai., 2009). '' '' 20% 0% Playing Time Distance Covered o High-lntensity Running " Sprinting "' High-speed running "' Running ., Jogging "' Walking " Standing Fig. 3. 1: Average values of different activities during English Premier League matches. Va/ues are expressed both as a percent of total p/aying time and distance covered (Data from Bradley et ai., 2009). 3.4 COMPETITIVE STANDARD Research has shown players ata higher standard of play to perform more high-intensity running than their peers at lower standards (Bangsbo et al., 1991; Mohr et al., 2008). For instance, Mohr et ai. (2003) found that elite Italian League players performed 28% more high-intensity running than sub-elite Danish League peers. Similarly, Ingebrigtsen et al. (2013) reported that distance covered in high-intensity running was 31-38% greater in players in top-ranking Danish teams when compared with middle- and bottom-ranking Danish teams, Based on this data, one would assume that the distances covered at high-intensity increase as we move up the competitive standards, but this is not entirely correct. For instance, studies demonstrate that players cover more total distance and perform more high-intensity running when playing against higher-quality opponents in the sarne domestic league (Castellano et ai., 2011; Di Salvo et ai., 2009; Rampinini et ai., 2007). There are also no differences in the activity profiles of international players and those who play in the best domestic European leagues (Bradley et al., 2010). Thus, the relationship between competition standard and physical match performance is more complex than we might initially think. Interestingly, English Premier League players (top tier) cover less distance at high-intensity than Championship (middle tier) and League 1 players (bottom tier) (Figure 3.3). Given there were no real differences in the physical capacity of the players at each tier, it was concluded that this trend was related to the style of play used in the lower tiers, with the Championship and League 1 teams employing a more direct style of play while the Pre~ mier League teams used a more possession-based style. This tvas evidenced by 1 35 36 FITNESS IN SOCCER FITNESS IN SOCCER 1 The physícal demands of elite soccer match p/ay The physica/ demands of elite soccer match pfay more successful passes in the Premier League and more long passes, headers, clearances and interceptions in the lower tiers (Bradley et al., 2013a). Thus, it seems that tactical variables and style of play have an influence on the distances covered by elite players. It is important to note that while Premier League players cover shorter match distances at high intensity, it does not necessarily mean the overall match demands are markedly different than in the lower tiers, because Premier League players may display superior accelerations or decelerations and lateral movement profiles that are metabolically taxing (Osgnach et ai., 2010). :§: 1800 ** ~ ·;;; 1200 e: .l!le: 'T .e :e"' "'"' 600 ~ > o EPL CH L1 Standard Fig. 3.3: Very high-intensity running profi/es in the Eng/ish Premier League (EPL), Championship (Ch) and League 1 (L 1) players. (Data from Bradley et ai., 2013a). 3.5 GENDER DIFFERENCES The relative physiological loadings experienced during matches are similar for both genders, suggesting that the aerobic system is heavily taxed throughout matches, particularly during intense periods (Bangsbo, 1994; Krustrup et al., 2003, 2005, 2006, 2010; Mohr et al., 2004). Female players, however, seem to possess a lower physical capacity than male players across a range of aerobic and anaerobic fitness tests (Bradley et al., 2011, 2012; Mujika et al., 2009). Thus, it is not surprising that studies have reported that high-intensity running in elite female matches is around 30% lower than that of their male counterparts ata similarly competitive standard with similar total distances (Krustrup et al., 2005; Mohr et al., 2008). Recently, Bradley et al. (2013b) analyzed the gender differences in the match performance characteristics for male and female players taking part in the UEFA Champions League. They found that while male players covered just -2-5% more total distance than female players, they performed -30-35% more high-intensity running and had a superior technical performance {Table 3.1). This finding illustrates the importance of high-intensity running to the female game and the inferior anaerobic capabilities of female players vvhen compared to elite male players. Practical applications are clear, and this suggests that elite female players may possibly benefit from specific high-intensity aerobic and speed endurance training in the form of small-sided games or generic running drills (Ade et al., 2013). Male Players Physicalffechnical lndicators First Second Female Players Total First Second Total High intensity (m) 1049 1063 2112 854 718 1571 Time possession (s) 33.8 35.8 69.6 34.6 31.9 66.5 Total balis lost (No.) 7.5 5.1 12.6 9.2 8.2 17.4 Successful passes (o/o) 78.1 80.1 79.4 72.0 70.4 71.5 Table 3. 1: Gender differences in physical and technical indicators for elite players in the UEFA Champions League (data from Bradley et ai., 2013b). 3.6 MATCH-TO-MATCH VARIABILITY ANO STABILITY When players' match performances are analyzed across a season, it is very evident that substantial differences exist between games. Mohr et al. (2003) reported that the hlgh-intensity running distances of elite players differed by approximately 10~~ between successive matches but it differed by 25% between different stages of the season using the coefficient of variation as the variability measure. Gregson et al. (2010) also found that English Premier League players' high-intensity and sprint profiles differed by 16-30% from one match to the next. The technical profiles of players seem to also illustrate similar differences, with the total number of passes for English Premier League players differing by approximately 30-50% from match to match (Bush et al., unpublished observation). This makes it very difficult for sports scientists to evaluate the impact of various technical, tactical and physical training interventions because of limited consistency in the performance measures. Substantial match-to-match variability is less likely to be caused by changes in physical capacity, because this does not differ substantially in the short term, but it could also possibly be dueto technical, tactical and contextual factors. 3.7 CONTEXTUAL ANO TACTICAL FACTORS Research examining contextual factors-such as match status (i.e., win, lose or draw), location (i.e., home or away), levei of opposition (i.e., top, middle or bottom) and match half-demonstrates these have a real impact on the activity profiles of elite players (Lago et al., 2012; Catellano et al., 2011). For instance, Castellano et al. (2011) found the distance covered when the ball was in play (effective playing-time distance) in various movement categories to be greater when playing at home rather than away, as well as when the opposition team was losing and of a higher competitive level. Other contextual factors, such as score line but not match importance, also seem to be important factors in dictating physical performance. Bradley and Noakes (2013) observed that elite players covered similar high-intensity running distances in matches with differing score lines, but position-specific trends indicated that central defenders performed 17% less high-intensity running and attackers 15% more during matches that were decisively \Von when compared to matches that were lost. However, high-intensity iunning distances were com- 1 37 FITNESS IN SOCCER FITNESS IN SOCCER The physical demands of elite soccer match play The physical demands of elite soccer match play parable over matches of differing importance (e.g., games linked to relegation or promotion and local derbies), but tren<ls between halves indicated that declines only occurred in the second half of criticai matches when compareci to matches of less importance. Tactical factors, such as the playing formation, also seem to be an influential factor on the physical performance of elite players. For instance, no differences were found in the overall physical profiles of players playing in 4-4-2, 4-3-3 and 4-5-1 formations, but high-intensity running with ball possession in offensive and orthodox formations was approximately 30-40% higher than it was in defensive formations (i.e., 4-3-3 and 4-4-2 vs. 4-5-1). ln contrast, around 20% more distance was covered at high-intensity without possession in defensive formations when compared to offensive and orthodox formations (Bradley et al., 2011). This coincided with the lowest bali possession for the defensive forrnation when compared to the offensive and orthodox forrnations (44% vs. 50%), so ball possession could have been a factor. This clearly indicates the complexity of match play, and sports scientists and coaches need to consider various contextual and technical factors before making inferences from the time-motion data supplied by match analysis companies. 3.8 FATIGUE DURING MATCH PLAY Research demonstrates that physical performance declines between the first and second halves of elite match play (Oi Salvo et ai., 2009; Mohr et al., 2003), although others only observe minimal differences (Bradley et al., 2013a). Reductions in match running performance in the second half, or temporarily after the most intense period, could be attributed to fatigue (Bradley et al., 2009; Bendiksen et al., 2012; Di Mascio and Bradley, 2013; Krustrup et al., 2006), pacing strategies (Bradley and Noakes, 2013), ar contextual variables (Lago et al., 2012). They could also be related to the time the ball is out of play and the available opportunities to engage in match activities (Carling and Dupont, 2011). Although each factor has the potential to impact the physical performances of elite players, match-índuced fatigue seems evident, because physical capacity markedly declines after matches in comparison to baseline measures (Krustrup et al., 2010; Mohr et al., 2004). Thus, fatigue results in an inability to repeatedly cover distances during criticai situations, and it could also reduce technical capabilities that are important indicators of match outcome (Rampinini et al., 2009). Down regulation of running performance in the second half could be attributed to fatigue because studies have reported depleted muscle glycogen stores at the end of a match (Bendiksen et al., 2012; Krustrup et al., 2006). There are also temporary declines after intense periods of match play that are related to depletions in muscle creatine phosphate, changes in intramuscular acidosis, or the accumulation of potassium in the muscle interstitium (Krustrup et al., 2006). Altematively, some suggest that reductions in match running performance could be caused by players employing conscious or subconscious pacing strategies aimed at successfully completing the match (Bradley and Noakes, 2013). Although this is an attractive hypothesis, there is limited data to support or reject such a statement. Carling and Bloomfield (2010) observed how teams coped with an early player dismissal by sparing low-intensity activity in an attempt to preserve essential high-intensity running, and this possibly suggests pacing or modified tactics. If players pace their efforts, then only covering "low" to "moderate" distances in the first half enables them to have the available capacity to maintain match running performances in the second half. Although, some studies have established this, it is important to realize that other factors could be responsible for these findings (Bradley and Noakes, 2013; Rampinini et al., 2007). It seems players don't really tax their full physical capacity during matches, but they certainly do during intense periods when they perform a flurry of high-intensity bouts with minimal recovery, such as during the peak five-minute period. If you observe the following five-minute period, you will typically see it is 8-12% below the game mean, possibly indicating temporary fatigue (Figure 3.4). The practical application of these findings is that sports scientists should condition players to be able to cape with multiple bouts of intense actions with speed endurance drills in small-sided games or with a generic drill format (Ade et al., 2013). Typically, speed endurance maintenance training would be best for this, and coaches should employ exercise bouts with a varied duration (e.g., 30-90 seconds) with reduced rest periods (e.g., 1-3 times the exercise duration) across 6-12 repetitions. Research recommends this type of training to enhance the players' capacity to sustain high-intensity actions and recover from intense periods (Bangsbo, 1994; laia and Bangsbo, 2010). .§, ..• 300 ""•e. 250 o e "ê ' 200 .s"' .." e 150 e 100 •• .f'• 50 •• o ~ 1 .!! ~ Pc:ik 5-min Ncxt5-min Fin:il 5-min Mcan5-min Timc(min} Fig. 3.4: The most intense period of English Premier League matches and the drop in performance in the fol/owing five-minute period when compared to the mean five-minute period. 1 39 FITNESS IN SOCCER FITNESS IN SOCCER The physical demands of elite soccer match play The physical demands of elite soccer match play SUMMARY During elite matches, players cover 9-14 km of distance in total, with high-intensity rnovement accounting for 1-3 km. Central and wide midfielders typically run more total distance than all other positions, with the wide midfielders and fullbacks also displaying superior high-intensity activity profiles. Central defenders tend to exhibit the lowest physical performances during a game. However, the physical profiles of players in various competitive standards are influenced by the technical, tactical, and physical aspects of the game. For instance, in the English game, lower-tier teams use a more direct style of play compared to the top-tier teams, and this results in more distance covered at high intensity. The distance covered by players is also influenced by match location, opposition standard, score line and game half. Substantial match-to-match variability is evident in the physical and technical performance measures for elite soccer. This is unlikely to be due to changes in physical. capacity, but it could possibly be caused by technical, tactical and contextual factors. Finally, reductions in match running performance in the second half, or temporarily after the most intense period, could be attributed to pacing strategies, contextual variables, and depleted muscle glycogen levels. Good nutritional practice may help to attenuate the decrement in running performance in U1e second half of matches. The importance of nutrition in soccer is discussed in the following chapter. REFERENCES Ade,/., Harlc}~J. and Br.1dley, P.S. (in revicw). Thc Physiological Rcsponw, limc-Motion Chor«Ctcriotic; and Rcproducib1lity ofVarious Spced Enduran<:<> Drills in Elite Youth S-Occer Player:;: Sma!! Sidcd Gam!.'S vs Gcncric Running. !ntJ Sports l'hy and Pcrf. Ali, A. and l'mwlly, M .. 1991. Rccording soccer playcr:/ hcJrt rat~'S during malches. J SporlsSci, 9, pp.183-189. Biing,bo, J., 1994. Tiie phyr.iology of socccr--with spccial referen<:<> lo inte""" inlcrmitlcnt cxcn:is?. Acta Physiol Scand Suppl, 619, pp.1-155. Banr;'>bo, )., Norresaard, L and Thor:;o, F., 1991. 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Mcd Sd Sports Excr.:, 37, pp,1242-1248. Kruotrup, !'., Mohr, M., Slccnsberg. A, llcnch, J., Kjacr, M. and Dangsbo, )., 2006. Musclc and blood mclabo!itcs during a soccer g,1mc: implications for sprint performance. Mcd Sei Sporls Exerc, 38, pp.1165-l174 Krw;trup, P., Zcbio, M., Jcru;cn, J.M. and Mohr, M., 2010. Gamc-mduccd fot•guc pattcms in elite fcmale toccer. / Stn:nglh Cond Rcs, 2.J, pp.437-141. L.1go-Pcn"--S, C, 2012. The role of situational variablcs in analysing physical performance in soc<:<>r. J Hum Kinet,35, pp.89·95 Mohr, M., Krustrup, P. and llang~bo,J,, 2003. Matd> J"'rformance ofhigh-standard "occcr playcrs withspccial refcrcn<:<> lo dewlopmcnl of fatigue. J Sports Sei, 21, pp.519-526 Mohr, M., Krustrup., P, and Bangsbo, )., 2005. Fatigue insocrcr: a brief revicw.J Sporw Sei, 23, pp.593-599 Mohr, M., Kruolrup, P., Andcrs.:;on, H., Kirkcndal, D. and llangsbo, J., 2008. Malcl1 ac!ivitics of e!ite womcn wcccr playcr.; at dificrenl pcrforman<:<> lcvcls.J Strength Cond Rcs22, pp.341-349. Mohr, M., Kru~trup, P., Nybo, L, Niclscn, J.J. and llange,bo, )., 2004. Musde lcml"'mture and ~prinl pcrforman<:<> during socccr match1..-s-bcncfieial cfícct of re-warm-up at half-timc, Scand J Mcd Sei Sporls, 14, pp.156-162. Mujib, 1., Sanliotcb.1n, J., !mpclliucri, F.M. and C.1,;tugno, C., 2009, Filncso dctcrminanto of oucccss in mcn's and women's footboll. J Sports Sd, 27, pp.107-11.J. Oq;nach, C, Poscr, S., Bcmardini, R., Rinaldo, R. and di PramJ"'ro, P.E., 2010. Encrgy coõt and metabolic power in elite Goc.xr- a ncw matcl1 analyr.is approach. Mcd Sei Sports Excrc, 42, pp.170-173. Rampinin~ E., Cou!ls, A.J-, C.1ot~gnn, C., Sar"3i, R. and lmp<!lfüzcri, F.M., 2007. Variation in top leve! soc~r mnlch performance. Jnt J Sports />.fod, 28, pp.1018- lOU. 42 FITNESS IN SOCCER FITNESS IN SOCCER 1 Nutrition The physical demands of elite soccer match play NUTRITION Jean-Pierre Meert, Sally Hora, David Tenne~ Jan Van Winckel 4.1 INTRODUCTION Nutrition can significantly influence a soccer player's health and athletic performance. Most athletes realize that food choices are important, but many underestimate just how much of an impact the right dietary choices can have on success in their sport. Good nutrition cannot replace talent, skill, or physical training, but it can support and enhance all of these. When elite players compete, the small details often make the difference between a win and a loss. Diet is one such detail. The foods athletes choose for training and competition will affect their ability to train and compete. While attention is often given to the composition of pre-match meals, the everyday training diet is at least as important. A good diet helps promote adaptation to training, resulting in greater improvements for the sarne training load and/or skills practiced. It also provides nutrients to support the immune system, aid in post-exercise recovery, minimize injuries, and expedite recovery from injuries. There are many opinions about the best way for athletes to eat, but ultimately, nutrition is a science rather than an opinion. The emerging field of sports nutrition involves an understanding ofbiochemishy, bioenergetics, endocrinology, and exercise science that guides dietary recommendations to help optimize sport performance and associated health parameters. 4.2 ENERGY What is energy? Simply put, energy is the capacity to do work. Food contains energy, which is ultimately used to power physical activity. Energy is generally measured in joules (J), where 1 joule is defined as the energy used to move 1 kilogram (kg) a distance of 1 meter (m) with a force of 1 Newton (N). However, the energy in food is usually measured in calories. A calori e (cal) is defined as the amount of heat needed to raise the temperature of 1 gram (g) of water by 1 degree Celsius (ºC). ln practice, ldlocalories are typically used (kcal or Cal). One kcal or Cal is equal to 1,000 cal. The conversion of kilojoules (kJ) to kilocalories is dane by dividing the value in kJ by 4.2. 1 kcal =1 Cal = 1,000 cal 1 kj = 1,000) kcal = kj / 4.2 Example: 1,000 kj 238 kcal FITNESS IN SOCCER FITNESS IN SOCCER Nutrition Nutriiion 4.2.1 Energy Requirements Soccer is an intermittent, high-intensity sport with a high energy expenditure. It is characterized by short bursts of high-intensity activity combined with intermittent bouts of rest or low-intensity aerobic activity (e.g., walking or jogging). Studies estimate the average heart rate of players during a match to be approximately 85% of maximum heart rate (HRm~J, with a corresponding respiration of 70-75% maximum oxygen consumption (V02mnJ· This suggests that average exercise intensities are around the lactate threshold, with periods above and below this threshold during high energy bursts and recovery periods, respectively. This indicates that the energy demands are high, so attention must be given to supplying adequate fuel for h·aining and competition. It has been estimated that professional male soccer players expend about 1,500 kcal per match. Energy expenditure for female players has been estimated at approximately 1,100 kcal per match. This gender difference is due in part to smaller body mass and differences in body composition, but it is also likely linked to ·a greater tendency by female athletes to significantly under-fuet suggesting their performance may become more compromised as the game progresses because of fatigue caused by low fuel availability. Indeed, with both male and female players, one of the most common nutritional errors is under-fueling, resulting in early fatigue, decreased performance, and increased errors and injuries. The total energy requirement for each player is unique and a combination of the requirements of the basal metabolic rate, the thermal effect of food, the thermal effect of activity, and in some instances, growth (Burke et al., 2006). 4.2.1.1 A soccer player's energy consumption A player's energy expenditure can be expressed in an equation that includes the following elements: 1. Resting metabolic rate (RMR), which consists of the basal metabolic rate (BMR) and the sleep metabolic rate (SMR) 2. Thermal effect of food (TEF) 3. Energy expenditure for activities of daily living or the thermal effect of the activities concemed 4. Energy for the player's sporting activities. 4.2.2 Metabolism To determine an athlete' s energy requirements, we must start by assessing the baseline energy needs. Basal metabolic rate (BMR) is the minimum level of energy required to sustain the vital functions of the human body and regulate body temperature when awake. A person' s BMR is influenced by age, gender, weight, diet, exercise and ambient temperature. BMR is calculated based on a person's oxygen consumption. When resting, the body consumes about 0.3 liters of oxygen per minute and bums a mixture of (mostly) carbohydrates (CHOs) and fat as fuel. Although the average non-athlete burns around 2,000 kcal per day, figures over 10,000 kcal/ day have been measured in elite athletes. Beyond the kcal needed for vital functions, additional energy is needed for the activities of daily life and physical exercise. When added to the BMR, this is referred to as the active metabolic rate (AMR) and represents the total number of kcal burned on a typical day. Severa! formulas have been developed to estimate BMR values. The equation most widely accepted to be the most accurate is the Mifflin-St Jeor Equation (kcal/ day}: Male: (9.99 x weight) Female: (9.99 x weight) + + (6.25 x height) (6.25 x height) - (4.92 x age) + 5 (4.92 x age) - 161 1.veight in kilogranis, height in centi1neters, age in years When possible, it is always best to use measured BMR values because studies suggest that calculated values may underestimate the energy expenditure of trained athletes. This is likely due to higher than average muscle mass and physiological adaptations to training. The quantity of energy calculated for BMR is multiplied by an activity factor to account for relevant daily activity: Very low BMR * 1.3 Low BMR * 1.6 Moderate BMR * 1.7 High BMR * 2.1 ln most cases, a player's daily activity levei outside of the sport can be described as light. Energy needs can thus be estimated by BMR (using the Mifflin-St Jeor Equation above) and then multiplying the result by an activity factor of 1.3. The kcals associated vvith sporting activities are then added. The energy requirements for sporting activities can be calculated separately using metabolic equivalent (MET) values. One metabolic equivalent (MET) is defined as the metabolic rate for someone at rest sitting quietly in a chair (which corresponds to approximately 3.5 ml 0 2 /kg/min). The MET value for soccer is generally accepted to be 10.3 (kcal/kg/hr), but it may be higher in some elite athletes. The energy expenditure for an activity is calculated using the following equation: (kg body wt) x (MET value) x (hours of activity) = kcal for activity FITNESS IN SOCCER FITNESS IN SOCCER Nutrition Nutrition Example: For a 20-year-old rnale athlete who is 185 cm tall and weighs 80 kg • Mifflin-St Jeor Equation (9.99 x 70) +(6.25 x 185 cm)- (4.92 x age)+ 5 = 799.2 + 1156.25 - 98.4 = 1857.05 kcal/ day (calculated BMR) • Activity factor to allow for activities of daily living (1857.05 kcal/ day) x 1.3 = 2414.2 kcal/ day • Add in energy needs for 90 minutes of training or game (80 kg) x (10.3 MET) x (1.5hr)=1,236 kcal dueto sportíng activity • Total energy requirement per day = (2,414.2 kcal) + (1,236 kcal) = 3,650.2 kcal/ day 4.3 SUBSTRATE UTILIZATION ANO MACRONUTRIENT NEEDS There are four sources of energy in the human diet. 1. CHOs 2. fats 3. proteins 4. alcohol Energy value of the various nutrition components: 1 g of CHO 16 k) or4 kcal lgoffat 37kjor9kcal 1 g of protein 17 k) or 4 kcal 1 g of alcohol 23 k) or 7 kcal CHOs and fats are the prima1y sources of energy for metabolic processes. While protein can supply energy, it is not its primary function. Protein (or its subcomponents, amino acids) are the building blocks of cells, so the body prioritizes them as an available substrate for building and repairing muscles and other tissues. Under normal resting conditions, protein only contributes 10% or less of the body's total energy. However, the body is resourceful, and it will use whatever is available for fuel, so if there is limited CHO available, the body will burn a higher percentage of protein and fat as fuel. Since fat cannot be used as fuel under anaerobic conditions, this means a greater percentage of protein is used for fuel when CHO is limited during intense exercise. The source of that protein is either muscle catabolism or free amino acids, which will then be unavailable for muscle repair and recovery. A player whose diet is inadequate in CHOs will therefore have compromised performance and recovery. 4.3.1 4.3.1.1 Carbohydrates (CHO) Varieties CHOs are composed of carbon, hydrogen and oxygen. Their only function is to provide a continuous source of energy to cells. They are classified based on the number of saccharides (sugar molecules) or their degree of polymerization. 1. Monosaccharides: glucose, fructose and galactose. These single-molecule sugars are the basic units of all CHOs. 2. Disaccharides: sucrose, lactose and maltose. These contain two sugars attached to each other. The well-known sucrose, used on a daily basis as table sugar, contains a glucose molecule and a fructose molecule. Sucrose =glucose+ fructose (table sugar) Lactose = glucose + galactose (milk sugar) Maltose = glucose + glucose 3. Oligosaccharides are short chains of three to ten monosaccharides linked together. These are commonly found in dried beans and peas (legumes). 4. Polysaccharides are polymers derived from glucose. These are chains of tenor more monosaccharide units linked together. There are short-chain (10-15 monosaccharide units) products, which are used in sports drinks, obtained through the enzymatic breakdovvn of starch and other long-chain products. Starch is the form in which CHOs are stored in plants. Most starches can be easily broken down in people's intestines via enzymes, but a subcategory, referred to as resistant starch, is more difficult to digest. Resistant starch can be defined as any starch that escapes digestion in the small intestine and passes to the Iarge intestine for fermentation by the microflora residing there. Some starches that can be broken down are made resistant by the way they are treated. For example, baked potatoes that are kept in the refrigerator become resistant. There are hvo forms: amylose, a linear chain of glucose molecules, and amylopectine, a highly branched chain of monosaccharides. There are also non-starch forms, such as cellulose, pectins and gums. These are classified as fibers and cannot be digested by humans, but they can be beneficial in regulating bowel function and blood cholesterol levels. FITNESS IN SOCCER Nutrítion 4.3.1.2 FITNESS IN SOCCER Nutrition Properties 4.3.1.3 CHOs are energy providers. This is their main function. Monosaccharides and disaccharides are sometimes referred to as simple sugars. They are typically sweet and often used for taste and stimulating appetite. Fructose is the sweetest, with sucrose, glucose, maltose and lactose in decreasing arder of sweetness. Because simple sugars are easily digested and quickly absorbed into the blood stream, they are also described as fast sugars, and they are especially useful where sugar is needed immediately to help increase or maintain blood sugar leveis. Thus, they can provide a quick and easily digested fuel source during sporting activity as well a~ aid in glycogen repletion and provide a fuel source for post-exercise recovery. Oligosaccharides and polysaccharides are collectively known as complex CHOs, and these are slower to digest and absorb into the blood stream. Because of this, they provide a more gradual and sustained rise in blood glucose than an equivalent amount of simple sugars. These are primarily the starches. They also have important roles in sports nutrition: 0 They have an important part in glycogen recovery: 8-10 g of CHO per kg of body weight per 24 hours. o They help in the immediate recovery after a match or training session: possibly replenishing lg per kg oi body weight. 0 3-4 hours before a match: 4 g of CHO per kg o During physical exertion: 30-60 g of CHO per hour (can be a combínation of simple CHOs and easily digested complex CHOs, as tolerated by individual athletes). 120 60·~-~'.:::::::::::::'.',,~-""~---.'\,L___ J 40J------------',-~"~"'"-"~----c0?\-· -e-10% c~rbohydrate diet -2-40% C3rbohydratc dict ,, .1----------------CY.•""':.____ Tr~!ning = 100) Food Serving size (g) Glycemic load per serving Bakery products and breads Baguette, white, p!ain 95 30 15 White wheat f!our bread 71 30 10 Whole wheat bread, average 71 30 9 30 50 8 Coca Colaº, average 63 250 mL 16 Fanta0 , orange soft drink 68 250 mL 23 Apple juice, unsweetened, average 44 250 mL 30 Gatorade 78 250 mL 12 Orange juice, unsweetened 50 250 mL 12 30 23 Wheat tortil!a Beverages Breakfast cereais and related products ~ aot--~·~-,'-----\---,'----\c---7'~-o Glycemic index (glucose +-"\-------;<r-------:;;:-------- l 100 t-··-',-·-·---;;/'C---'~--·-···-,"'-·-'1---·---··-;?''-­ Í G/ycemic índex and glycemic load The glycemic index (GI) is a means of identifying the relative rate at which various types of CHOs are converted to blood glucose when consumed (Table 4.1). The closer this figure is to 100), the more quickly the blood sugar will rise after the CHO is consumed. CHOs with a high GI are absorbed quickly and can therefore be ingested during physical exertion. The term "glycemic load" was introduced in recent years to describe the relative glycemic response of a normal portion. For example, 50g of glucose has a higher glycemic load than 50g of carrots. The values used for this are 1-10 for a low load, 11-20 for a medium load and more than 20 for a high load. sesslons of 2 hours Cornflakes ™, average 93 Muesli, average 66 30 16 Special Km (Kel!ogg's) 69 30 14 Couscous, average 65 150 9 White rice, average 89 150 43 Quick cooking white basmati 67 150 28 Brown rice, average 50 150 16 41 250mL 5 33 200 11 Apple, average 39 120 6 Banana, ripe 62 120 16 Oays Fig. 4. 1: GHO reserves CHO rese1Ves in lhe form of g/ycogen in the musc/es. ln the case of a low-GHO diet, a series of training sessions will lead to depletion of the musc/e glycogen. A high-GHO diet will maintain the musc/e glycogen reserves at an acceptabfe levei. Dairy products and alternatives Mi!k, full fat Reduced-fat yogurt with frui!, average Fruits 501 FITNESS IN SOCCER Nutrition FITNESS IN SOCCER Nutrítion Beans and nuts 6 Baked beans, average 40 150 Cashews, salted 27 50 3 7 50 o Peanuts, average Pasta and noodles 32 180 15 Macaroni, average 47 180 23 Spaghetti, white, boiled, average 46 180 22 Spaghetti, white, boi!ed 20 min, average 58 180 26 Spaghetti, wholemeal, boiled, average 42 180 17 50 11 Fettucini, average Snack foods Corn chips, plain, sa!ted, average 42 Microwave popcorn, plain, average 55 20 6 Potato chips, average 51 50 12 Green peas, average 51 80 4 Carrots, average 35 80 2 150 21 Vegetables 4.3.2.1 82 Boiled white palato, average Miscellaneous Hummus {chickpea sa!ad dip} 6 30 o Pizza, plain baked dough, served with parmesan cheese and tomato sauce 80 100 22 Table 4. 1: ilfnternational tab/es of glycemic index and g/ycemic foad values: 2008" by Atlrinson et ai. (2008) Recovery \a:J±Filli ~ o -'------------------ ~ .:t;-~<;-% '\- ~ '\.O '?O r,,..O .:.,O ,,.* -@-Carbohydrate diet --:~::;~"Fat and protein diet õ'l:t~<, " Hours recovery Fig. 4.2: Effect of diet and the recovery of musc/e g/ycogen reserves after a two-hour training session Dietary Fats Fats are an important part of a well-balanced diet and have many crucial functions in the body. They are components for cell membranes, hormones, and of the myelin sheath that protects nerve cells. Fats are also necessary for temperature regulation, shock absorption, and the transportation and absorption of fat-soluble vitamins (A, D, E, andK). Fat can be used as a fuel during physical exercise and is a significant source of fuel for physical exertion of a moderate to low intensity (<60% vo2mil) and long duration (> 30 minutes). The utilization of fat as an energy substrate requires adequate oxygen, so it is only a significant source of fuel under aerobic conditions. During high-intensity, anaerobic activity, there is insufficient oxygen for fat to be oxidized. Other factors that affect the body's ability to use fat as a fuel include the nun1ber of mitochondria in the muscle cells and the ratio of different types of muscle fibers. Type I muscle tissue tends to store more triglycerides than type II muscle tissue. 4.3.2.2 _25~---------------- í~ 4.3.2 Fat The FATmax zone is the zone where energy is provided primarily by the oxidation of fat. This zone is located between 55% and 70% of V0 2max or between 65% and 75% of the HRm,,x· This zone varies considerably between individuals. It is flawed to claim that the best way of burning fat is through long, monotonous endurance training. A well-trained athlete burns approximately 220 kcal during a 30-minute run at 50% of V0 2mJx· If the sarne person ran at 75%, he or she would then burn 330 kcal. At 50% of V02 max' 50% is produced by the burning of fat, while the equivalent figure at 75% of V0 2 m~x is 33%. This means that the sarne amount of fat is bumed in both cases (i.e., 50% of 220 kcal and 33% of 330 kcal, resulting in 110 kcal being consumed from buming off fat in both cases). However, the more intensive workout at 75 % of VO~ consumes another 220 kcal from other sources. This means the more intensive ~~;k.out will burn more kcal than the low-intensity exercise, but it will utilize different energy substrates. Additionally, not all fat burned as a result of exercise is burned during exercise. While CHO may be the primary fuel used during high-intensity exercise, fat is a significant source of energy during post-exercise recovery when ample oxygen is available. Saturated and unsaturated fatty acids Dietary fats are typically differentiated by their positive or negative effects on our health. When consumed in excess, saturated fats and trans fats are believed to have detrimental effects on blood cholesterol levels, possibly contributing to high LDL cholesterol, cardiovascular disease, and inflammation. With the exception of tropical oils such as coconut oil and palm oil, most saturated fats come from animal sources and are relatively solid at room temperature. Examples include butter, cheese, lard, and fats found in meat and poultry. Trans fats, also known as hydrogenated fats, are found primarily in processed foods. Monounsaturated fats are considered to belong to the group of "good fats," because they are believed to have a positive effect on cardiovascular health and blood cholesterol. Monounsahtrated fatty acids are found in olive oil, avocados, and nuts. Omega-3 fatty acids are another beneficial dietary fat. They are believed to help regulate blood cholesterol, decrease inflammation, and stabilize moods and brain health. Additionally, there is FACULDADF OE DESPORTO DA UNIVERSIDADE DO PORTO sz I f ITN ESS 1N SOCCER Nutrítion evidence that omega-3 fats may help protect eye health in athletes whose eyes are often exposed to the sun. Omega-3 fats are found most commonly and abundantly in fish oils, but they are also found in a less concentrated form in flax seeds and flax seed oil. It is also important to be aware that fat is slow to digest and absorb, and it slows down the transit absorption of other foods consumed with it. Because of this, it is wise to avoid high-fat food immediately prior to physical exercise in arder to prevent food from uncomfortably sitting in the stomach during exercise. Likewise, consuming high-fat foods within the hour immediately following exercise may slow down the absorption of ingested CHOs and protein enough to interfere with optimal recovery. However, if consumed later, post-exercise dietary fats may be a good source of energy to help meet the high demands of the sport. 4.3.3 Proteins The amino acids supplied by dietary proteins are used in the body as building blocks for growth and the maintenance of muscle and organ tissue. They are also used for repairing other damaged tissues. Proteins can be used to build muscles and other tissues (anabolism) and can be broken down into amino acids (catabolism). Although nota preferred fuel, amino acids can be used as an energy source during exercise. The oxidation of protein during exercise is inversely related to glycogen availability. Thus, consuming a diet rich in CHO, which helps maximize glycogen stores, will in turn decrease the use of protein as a fuel source. This protein-sparing effect helps prevent the catabolism of muscle protein and the subsequent need to restore it during recovery (or the resulting risk of injury if not restored). Without adequate dietary CHO, an athlete's protein requirements increase because of increased protein needed for recovery and for fuel. When the diet contains enough CHO, protein needs are relatively small. Although athletes do have higher protein requirements than the general population, the requirements are not nearly as high as many athletes or coaches suspect. Proteins are composed of amino acids. There are 20 amino acids, of which eight are considered essential. Essential amino acids must be obtained from the diet because the human body cannot synthesize them. The biological value (BV) of a protein refers to its completeness for supplying essential amino acids. Animal proteins have high biological value, because they contain all of the essential amino acids. Proteins of plant origin (with the exception of soy protein) lack some of the essential amino acids, so they are considered to be of lower biological value. ln general, the essential amino acids absent in grains are present in legumes (dried beans, peas and lentils), and vice versa. Thus, even if a diet contains little orno meat, it can adequately provide all the essential amino acids if it includes a variety of both grains and legumes. A healthy, balanced diet that contains a variety of foods can easily supply sufficient protein for even elite athletes. FITNESS IN SOCCER Nutrition 4.4 ATP (ADENOSINE TRIPHOSPHATE) ATP, or adenosine triphosphate, is the biochemical carrier of energy for the movement of a muscle. We refer to movement rather than contraction because of muscular activity having different movement patterns (i.e., isometric, concentric and eccentric movement). ATP is present in the muscle cell to a very limited extent, barely sufficient for a few seconds. However, it can be deployed directly. ln other words, ATP has great power but very limited capacity. ln chemical terms, we can describe it as follows: ATP undergoes hydrolysis in the sarcoplasm, releasing energy that is used by the muscle filaments (actin and myosin activation). ATP + H,O produces ADP (adenosine diphosphate) + W (hydrogen ion) + Pi (free phosphorous ) + release of energy that can be used directly by the muscle. Because ATP is the only forro of energy that can be used directly by the cells, the small quantity has to be continuously replenished. This is done by converting the ADP by-product back into ATP. This requires energy from the various energy systems, which differ in their speeds of production (their power) and the quantity of energy they can produce (their capacity). 4.4.1 Replenishment of ATP To restore ADP to ATP, we have four systems. 1. ATP-CP system: Hydrolysis of phospho-creatine (PCr) in the sarcoplasm produces the immediate release of energy for converting ADP into ATP. The quantity of PCr is also limited, but it is the first energy system accessed, it responds very quickly, and it is sufficient to sustain exertion for about 8 seconds. This is the energy system responsible for short bursts of energy. This system is extremely important for soccer and the most important energy provider for typical high-intensity activities in soccer, such as short and repeated sprints, jumps, tackles, kicks, and so on. The pool of PCr can be increased to a limited extent through specially adapted training and creatine supplementation. 2. Anaerobic Glycolysis: produces energy in the sarcoplasm to ensure that the high intensity of an exertion can be sustained for longer than 10 seconds. In this regard, glycogen from the muscles is converted to pyruvate and lactate via a number of chemical steps in which no oxygen is used, releasing a limited quantity of energy (hvo or three ATPs depending on whether the source of glucose is stored glycogen or glucose coming from the bloodstream). At high intensity, it is mainly the muscle glycogen that is used and, at lower intensity, the blood glucose coming from the liver glycogen is used. 3. Oxidative Phosphorylation: For the exertion to be carried out longer, the intensity of the exertion falls and Aerobic Glycolysis (Oxidative Phosphorylation) takes over. The time that elapses before the system is in full \vorlcing order is determined by the level of training and genetic potential, and it follows an exponential function with values behveen 30 seconds and hvo minutes (which is the duration that anaerobic activity can be sustained). Aerobic energy production takes place in the mitochondria, with the glucose and fatty acid substrates converted entirely to water and C02• The CHO reserves are limited, \vhile fat FITNESS IN SOCCER Nutrition FITNESS IN SOCCER Nutrition reserves are virtually unlimited. Fats become the primary fuel source during low-intensity physical exertion where adequate oxygen is available for the oxidation of lipids. This is in contrast to the high-intensity anaerobic exertions, which are fuelled by CHOs. However, it is important to note that the use of fat as a fuel is most efficient when there is at least a baseline amount of CHO present. It is often said that fat burns best in the flame of CHO. Without adequate CHO, there is an incomplete combustion of fat that produces ketones as a by-product. While ketones can be used as a fuel source, they are not an efficient source of fuel, especially for the brain. Ketones are also known as keto acids, and as such, are a source of metabolic acidosis. CHO is therefore extremely important as a fuel source in soccer. 4. The Kinase Reaction can produce a limited amount of energy through the combination of tvvo ADPs (i.e., ADP+ADP produces ATP+AMP). This reaction is important for high-intensity exertions. Excessively high intensity at the beginning of a physical exertion can cause a very high quantity of AMP to be converted to IMP and further transformed into urea (typical smell of sweat in these cases), which causes an insufficient store of ADP and a need to discontinue the exertion. 4.5 ENERGY SYSTEMS These energy systems differ from each other in terms of: The use of substrate: Anaerobic energy consumes 18 times more substrate (although the end product, lactate, can be later reused by the cardiac muscle, for example, or converted to glycogen in the liver via the Cori cycle). Speed of action (power): the ATP-CP system is faster than anaerobic glycolysis, which in turn is quicker than aerobic phosphorylation. ·The quantity of energy they can produce (capacity): aerobic > anaerobic > PCr > ATP. Their power development expressed in watts: The maximum anaerobic power is 4-5 times greater than the maximum aerobic power. ATP /PCr generates a maximum of 5,000 watts, while anaerobic generates 2,000-4,000 watts. Aerobic generates less than 2,000 watts. There is also a noticeable difference in energy supply according to the muscle type. Type I: slow muscle cells, characterized by their fine structure and red colar {due to large amounts of myoglobins), mainly display aerobic energy production with little formation of lactate. They are economical •vith regard to substrate consumption because of the total oxidation of the energy sources (i.e., CHO, protein and fat). Type II: muscle cells, or white muscle cells, are subdivided into: Type lia: These have a mixed aerobic and anaerobic effect and are characteristic of soccer players (with a part of type IIb probably being transformed into type Ila). Type IIb: These are the strongest, but they have a mainly anaerobic metabolism with very high glycogen consumption. Conclusion: Given that physical exertion in soccer is partly anaerobic (during the brief high-intensity exertions) and primarily aerobic (repleting ATP leveis during the longer periods of recuperation), it is clear that the main energy source for soccer activity is CHO fron1 glycogen stored in the liver and muscles, as •vell as blood glucose from food and beverages consumed before and during play . ATP-CP system Anaerobic process Aerobic process lntensity 95-100% 60-95% < 60 %) Duration < 10 sec 30 sec to 30 min Long duration Fue/ Creatlne phosphate CHOs (from b!ood glucose and stored glycogen } CHOs, fats, proteins Residual product Nane Lactic acid Water and carbon dioxide Recovery lmmediate 20-60 min Until the fuel reserves have been replenished Tab/e 4.2: Overview of lhe different energy systems. i ss ss FITNESS IN SOCCER I Nutrition 4.6 MACRONUTRIENT NEEDS Due to the limited supply of both sources of CHO (i.e., 350g of muscle glycogen, 120g of liver glycogen, and 5g of blood glucose), constant replenishment via food and drink is an absolute necessity. Macronutrient needs are sometimes expressed as percentages of the total kcal needed, which is calculated based on body weight, age, gender and everyday activities. With this system, 70% of an athlete's energy is provided by CHOs, 20% by fat, and the remaining 10% by protein. However, most sports nutritionists now provide macronutrient recommendations in terms of grams per kilogram of body weight (g/kg BW), and this is a more precise way of targeting the needs of individual athletes. With this method, the CHO recommendation for soccer players is 5-7g CHO/kg BW for moderate daily recovery and match preparation. During times of enhanced daily recovery and match preparation (e.g., heavy training loads, frequent matches and/ or injury recovery) 7-12g CHO /kg BW is recommended. If the diet does not contain enough CHOs, athletic performance and muscle recovery will be compromised. The majority of these are complex CHOs-present in bread, rice, vegetables, and so on-with a small portion of simple sugars that are often added to the food. The recommended protein intake for the training diet of elite soccer players is l.4-l.7g/kg BW. While slightly higher protein consumption may be helpful for athletes recovering from injuries or surgery, research suggests there is no advantage to protein intakes greater than 2g /kg BW in daily training diets. In fact, protein regularly consumed at these leveis may have detrimental effects, such as increased risk of dehydration, kidney stones, calcium loss, GI distress, gout, and liver or kidney damage. Among other concerns, there is an increased risk of dehydration when high amounts of protein are consumed due to the obligatory water lasses associated with the excretion of urea, which is a by-product of protein oxidation. Fat appears to be the macronutrient that requires the least precision in terms of balancing the diet. Generally speaking, once CHO and protein needs have been calculated, the remaining kcals can usually come from the healthier varieties of dietary fats. The acceptable amount of dietary fat for most athletes is between 10% and 30% of total energy intake. Healthy varieties of fats include monounsaturated fats-such as those found in nuts, clives and avocados-and omega-3 fatty acids, which are found in fish oil and flax seed oil. It is best to limit saturated fats (found in cheese and other dairy products and in meats) and trans fats (found in processed foods containing hydrogenated oils). Excess amounts (more than 10% of dietary energy) of these latter two types of fats can increase the risk of heart disease and contribute to inflammation. Omega-3 fats, on the other hand, may actually help decrease inflammation. FITN ESS 1N SOCCER Nutrition 4.7 EATING PATTERNS OF SOCCER PLAYERS Little research has been conducted regarding the dietary habits of soccer players. Glycogen reserves may decrease quickly during a match through the alternation between low- and high-intensity moments. A thirty-second sprint at full speed can reduce the glycogen concentration in the muscles by 30%. Top players work for two-thirds of a match at 85% of their HRm~~· Research has shown that soccer players expend up to 90% of their glycogen reserves during a match. Exhausting glycogen reserves leads to fatigue, guaranteeing fewer sprints in the second half. Eating an easily digested CHO before the match and drinking a sports drink (containing 4-6% CHO) during the half-time break increases the distance that can be covered at high speed in the second half. It is therefore not sufficient to consume a sports drink just before the match. The body needs to be trained to ingest sufficient CHOs before and after a match. At least 9-lOg of CHOs per kg of body weight need to be ingested over the few days before a match and during periods of intense training. 4.7.1 4.7.1.1 Food intake and beverage consumption before and after a match Prior to commencement ofthe match Nutrition is, of course, an important factor in the days leading up to a match. The day before the match, it is necessary to start replenishlng the glycogen reserves in the muscles (i.e., provide a diet rich in CHOs for the few days before a match). We use sports meals to enhance the body's CHO reserves, but trying out new foods before a match is not advisable. The best time to do this is before training. Always try to eat the sarne things prior to a match, because this helps to gather experience with regard to quantities. A full meal should be eaten at least three hours before the match starts. Eating within three hours of kick-off time can cause stomach problems during the game. A relatively empty stomach also helps ensure that the muscles have a sufficient supply of blood and oxygen. High-fat foods are not advisable because these slow down the digestion process in the stomach. The meal should be rich in complex CHOs-such as potatoes, rice, grain, fruits, and vegetables-while the quantity is determined individually and also influenced by the previous meal. Proteins can also be ingested provided they are not from a high-fat source. Examples of pre~match food: 0 cornflakes with low-fat milk 0 pasta (possibly with a low-fat sauce) o baked potatoes 0 fruit (e.g., raisins, bananas, oranges) o bread rolls • rice On average, around Sg of CHOs per kg of body weight should be ingested (e.g., 375g for a player weighing 75 kg). Additional CHOs should be eaten around two hours prior to the match in the form of bread or bananas. Try to eat or drink another SOg of CHOs 20 minutes before the match starts. ss FITNESS IN SOCCER I Nutritíon Examples of foods that contain around 50g of CHOs include: o two bananas 0 two slices of bread and jam 0 75g of breakfast cereal o biscuits 4.7.1.2 DUR/NG THE HALF-TIME BREAK The glycogen reserves need to be replenished during the half-time break. This can be achieved by eating two bananas or drinking a high-CHO beverage. Care must be taken to consume sufficient fluids along with any CHOs in arder to prevent an overly high solute load in the gut. If too concentrated, this will slow gastric emptying and cause "sloshing." 4. 7.1.3 After the matc/1 After the match, the glycogen reserves need to be replenished as quickly as possible. Muscle glycogen is produced considerably faster after physical exertion. Also try to consume around lg of CHO per kg/BW vvithin two hours of the physical exertion, and do not goto sleep on an empty stomach. 4.8 GLYCOGEN METABOLISM ANO NUTRIENT TIMING FOR RECOVERY ln this chapter \Ve have discussed the decisively important role of glycogen as a fuel for soccer players. Given the limited reserves in the body, it is ímportant to know how the level of glycogen stored ín the muscles and liver can be maintained or even increased. ln other words, we have to understand how the synthesis of glycogen works and \Vhat influences this. Glycogen synthesis (glycogenesis) is regulated via the enzyme glycogenin. Post-exercise glycogen repletion proceeds in two phases. 1. The rapid Plmse 1 is not dependent on insulin and takes about an hour. The formation of glycogen is controlled by the glycogen synthase enzyn1e, the activity of vvhich is inversely proportional to the initial glycogen store (i.e., the lower the glycogen reserves, the more active the enzyme becomes). The enzyme binds the first glucose molecules together. There is also an increased permeability of the cell membrane for glucose. 2. Phase 2 is insulin-dependent and ten times slower than phase 1 in the absence of CHOs. If CHOs are ingested directly after exercise, the synthesis of glycogen increases, and levels can even become higher than normal. This additional glycogen storage is known as glycogen supercompensation (often referred to as CHO loading). This phase of glycogen synthesis is also dependent on the type of exercise performed. A quick review of exercise endocrinology will help explain why. During moderate-to-high-intensity exercise, catecholamines (epinephrine, norepinephrine, glucagon, human growth hormone) are released in response to the physiological stress. These hormones help make fuel available for the active muscles by encouraging glycolysis and gluconeogenesis and by mobilizing fatty acids out of storage. FITNESS IN SOCCER Nutrition Insulin is a storage hormone that acts to get substrates (glucose and fatty acids) into cells for storage, so the release of catecholamines at the onset of exercise initiates a feedback loop that inhibits insulin secretion. During moderate-to-high-intensity exertion, the body activates an insulin-independent mechanism to transport glucose into the cells via GLUT4 receptors. There is an increased concentration of GLUT4 glucose transporters, which carry glucose from the cell membranes into the cells. The muscle's cells also become more sensitive to insulin during moderate to intense exercise. During post-exercise recovery, the insulin sensitivity and GLUT4 receptors remain elevated and active for about 60 minutes. At the cessation of exercise, catecholamine leveis decrease, allowing for a restoration of insulin secretion. This can rebound with an insulin response to CHO that is up to ten times greater than normal. Because insulin is a storage hormone, heightened insulin sensitivity combined with abundant insulin secretion allows for an increased capacity to transport glucose and protein into muscle cells for enhanced glycogen storage and muscle recovery. Additionally, high-intensity exercise leads to an increase in proteins that convey Jactate outside the cell and aid in the recovery of the cell. Experts emphasize the importance of refueling within 60 minutes after exercise, because this will take advantage of the temporarily enhanced ability to transport and store CHO and protein. The immediate administration of CHO at the cessation of exertion (training or n1atch) is therefore decisive for glycogen supercompensation. The question remains as to what CHOs to eat and in what quantity. Severa} studies have shown that, up to a certain limit, there is a parallel betvveen the quantity of CHOs absorbed and the quantity of stored glycogen. A range of 1.2 to l.67g of CHOs per kg/BW would appear to be ideal. Type of CHO: Preferably eat a mixture of simple and complex CHOs with a small amount of fructose (see below). Timing: Eat immediately after physical exertion (\vithin 30-60 minutes) and every 15-30 minutes for the next 2-5 hours post-exercise. Research has alsn shown that this regime can be continued for a fe\v hours, providing 1.0-1.Sg of CHOs per kg/hour. This can perhaps be provided in several small snacks and / or beverages every 15-30 minutes. Providing a small amount of protein post-exercise may enhance muscle recovery. Although athletes are often inclined to consume large quantities of protein at this time, research suggests that athletes only need 0.1-0.2g of protein per kg/hour for recovery from both endurance- and resistance-type exercises. For a 70kg person, this would be only 7-14g of protein. ln practice, this can be easily provided by consuming 250-500ml (8 -16 fl. Oz.) of low-fat chocolate milk. Chocolate milk is often touted as the "ideal recovery drink" because it provides the recommended amounts of CHO and protein, as well as fluid and electrolyte replacement (i.e., sodium, potassium and calcium). FITNESS IN SOCCER FITNESS IN SOCCER Nutrition Nutrition Food Grams (g) Serving size CHO (g) Bread 130 50 Pasta (cooked) 200 50 Muse!i 75 50 Rice (brown or white) 130 50 pretzels 15 cm across, {6") Torti!la {Corn or flour) 15 60 Naan lndian Bread 1 cup Oats, oatmeal, cooked 30 Corn 1 cup 30 Quinoa, cooked 1 Cup 45 1h Cup, cooked 15 Potato 250 Sweet palato ar Yam Beans, peas ar lentils Small (tennis ball size) 15 Mango 1 smal! ( 1 Cup) 30 Berries 1 Cup Melon 1/8 Ih ar 1 Cup cubed Apple, orange watermelon 1.25 Cup Unsweetened juice 4 oz 15 Jelly or Jam 4tsp Milk 8oz l<iwi 1 15 Dates 3 15 YiCup 15 Papaya 1 cup cubed 15 Raisins 2Tbsp 15 Pineapple Sorbet %Cup 30 Honey 1 Tbls 15 Sugar 1 Tb!s 15 1 bar 15 8 oz 30 Frozen fruitjuice bars, 100% juice Fruitjuice Table 4.3: CHO content offood. 500 mi Fructose is metabolized differently than the other sugars. Most sugars are absorbed from the intestine into general circulation, where they are then taken up by cells and metabolized. Fructose, in contrast, is transported from the intestine directly to the liver, the only place where fructose metabolism occurs. ln the liver, fructose is converted to glycogen, and once the glycogen stores are full, it is converted to triglycerides (fat). Because of this, fructose does not have a direct effect on blood sugar and therefore does not elicit an insulin response. Both of these factors cause tvvo times more glycogen to be stored via glucose. As already mentioned, fructose is metabolized primarily in the liver, while glucose is metabolized in the muscles. Because fructose has no direct effect on blood sugar, it is not an immediately available source of energy for the brain or muscles. Additionally, some athletes have an intolerance to fructose. These individuals often experience the symptoms of cramps, and fermentation can occur quickly in the area of the intestine. Fructose is therefore only useful in limited quantities because of its role in the storage of glycogen in the liver and its pronounced sweet taste. It does not appear to make a difference whether CHOs are ingested in solid or liquid forro. The type of exertion, however, does have an influence on the formation of glycogen, because there is a clear difference between prolonged aerobic exertion (longer than an hour) and short, high-intensity exertions. ln the first case, the synthesis is dependent on the availability of CHOs, while in the second case, the synthesis runs parallel to the fall in lactate level. (Lactate is used as a source for glycogen.) Eccentric exercises (such as in soccer) appear to have a negative influence on glycogen accumulation, possibly due to a decrease in GLUT4 proteins, although this rnay be a direct effect of a high demand for glycogen and inadequate CHO in the training diet. This can be countered by ingesting adequate arnounts of CHO and protein after the training session or rnatch. 4.9 4.9.1 ENERGY BALANCE AND BODY COMPOSITION Body composition The body is rnade up of 73.8% water, 19.4% proteins, and 6.8%.1 minerais. The ideal body cornposition varies frorn sport to sport. The body is divided into two components: fat-free mass and fat mass. Correct training can increase the fat-free rnass and reduce the fat rnass. The body rnass index is a test used to give an indication of body fat. However, it is a poor indicator of health in athletes because it is merely a ratio of height to weight. Athletes typically have more muscle rnass, which is denser than fat. Athletes with a lot of rnuscle mass score high on this index, giving an incorrect impression of body composition. BMI is calculated as follows: BMI (kg/ m') = body weight in kilograms divided by height in meters squared Example: Weight: 75 kg, height: 1.75 - BMI = 75 / (1.75 x 1.75) = 24.5 kg/ m' FITNESS IN SOCCER FITNESS IN SOCCER Nutrition Nutrilion FAT º/o Min. Max. Stdev. Avg 8.45 9.51 Elite U21 5.00 16.00 2.04 Elite First team 6.29 14.13 1.68 Tab/e 4.4: Reference data based on tests at different top cfubs (TopSportsLab). Height and weight vary considerably in soccer. Asmall build is nota disadvantage, but it can determine the choice of position on the field. ln soccer, there are considerable variations between the different positions, with defenders, strikers and goalkeepers being taller than players of other positions. A way of describing body composition is the somatotype. This is expressed in three dimensions: • endomorphy: indicates the tendency to put on weight • mesomorphy: indicates the tendency towards muscularity • ectomorphy: indicates the tendency towards linearity These values are measured based on the circumference of the person' s limbs, leg diameter and skinfold measurements. There are also other methods of measuring the somatotype by estimation. Soccer players tend toward 2-5-2, meaning that they are more muscular. Bach dimension ranges from one to seven (Table 4.5). Rugby (7 >< 7) 1 ,J\) Gaelic football Soccer Endomorphy 2.3 2.7 2.0 Mesomorphy 5.9 5.7 5.3 Ectomorphy 1.5 1.9 2.1 \ 1 \ I' Tab!e 4.5: Somatotype of top players in various forms of footbal! J( <'~.J Ectomorph Mesomorph Endomorph Fig. 4.3: Exemples of different somatotypes. The somatotype is expressed in three digits. Most peop/e have a somatotype somewhere in the midd/e. Mesomorph 1-7-1 Weight lifters Gymm1sts Sumo wrest!ers Tennis p!ayers High jumpers Endomorph 7-1-1 The average fat percentage for men around 25 years of age is around 16%. ln the literature, the value for soccer players is 9-13%, vvhile it is somewhat lower for individual athletes (e.g., track-and-field athletes). The values measured for top athletes are between 3% and 7%. Soccer players average out at around 9-10% fat. 4.9.2 Energy balance For most elite soccer players, balancing energy for the purpose of weight management is not a primary focus (exercise to eat). During active training seasons, the greatest challenge is supplying enough kcal and CHO to meet the substantial energy demands that result from training and match play (eat to exercise). Athletes who attempt to create an energy deficit in an effort to lose body fat often end up compromising their performance and/ or increasing their risk of injury. Ideally, any reductions in body weight should be done during the player's off-season. It is impossible to lose weight while simultaneously fueling for optimal performance. Likewise, it is unwise for an athlete to follow a low-CHO diet in an attempt to lose weight. This would interfere with the energy available for training and match play, resulting in reduced performance and increased risk of injury. Also, much of the weight loss associated with low-CHO diets is due to depleted glycogen stores, particularly the loss of the water stored \vith them. This can easily result in a loss of 5kg, but it will also remove a valuable source of stored fuel for sport while doing little, if anything, to <lecrease body fat. Ectomorph 1-1-7 Fig. 4.4: Somatotypes in different sports. Over the last decade, soccer players have evofved from being more ectomorphic to mesomorphic. It is better to focus on body composition rather than body weight, especially since the addition of muscle and/ or glycogen can significantly increase weight, because it is ultimately advantageous if the ability to produce power is increased. Studies suggest that elite male soccer players have around 8-13% body fat, while top FITNESS IN SOCCER Nutrition female players have approximately 16% body fat. The fat percentage is commonly measured with a skinfold caliper, which estimates the fat percentage on the basis of skinfold thickness. Care has to be taken with skinfold measurements where age is not taken into account, because older players tend to have somewhat thicker skin and are therefore likely to be overestimated. Other methods of estimating body composition include dual-energy X-ray absorptiometry, hydrostatic weighing, and bioelectrical impedance. 4.10 VITAMINS, MINERALSAND FREE RADICALS Vitamins, minerals and phytochemicals are micronutrients. They are only needed in small quantities, but they are vital in supporting health and growth. Micronutrients are involved in many metabolic processes. Six of the B vitamins (thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, and biotin) are necessary for the metabolic reactions that produce energy during exercise. Two others, vitamin B12 and folate, are essential to red blood cell formation, protein synthesis, and the growth and repair of tissues. Deficiencies of Bl2 and/ or folate result in macrocytic anemia, which compromises health and performance by limiting the amount of oxygen a given volume of blood can deliver to working muscles, the brain, and other vital organs. 4.10.1 Antioxidants Vitamins C, E, and A (beta carotene), selenium and several phytochemicals serve as antioxidants, which help to prevent oxidative damage to cells caused by free radicais. Free radicals, often referred to as "chemical terrorists," are molecules or atoms that contain an unpaired electron. They are highly reactive and can initiate chain-like reactions that can damage cell membranes and DNA, causing cells to malfunction or die. Antioxidants neutralize free radicais, thus helping to prevent or reduce the oxidative damage to body cells. Soccer players, like many other athletes, are at increased risk of oxidative damage to cells because the increased oxygen exchange associated with aerobic physical activities increases the exposure of cells to oxygen by 10-20 times. It is now believed that athletes adapt to regular training by developing an enhanced antioxidant defense system, so they are better protected against free radical damage than the occasional exerciser would be. Still, there may still be some advantage to providing dietary antioxidants to enhance protection from free radicais. All of the aforementioned antioxidants can be found in a diet that contains a variety of fruits and vegetables. No supplementation is necessary with such a diet. 4.10.2 Vitamin D Vitamin D is a micronutrient that has received increasing interest of late. The well-established functions of vitamin D include calcium regulation, bane health, and development and homeostasis of the skeletal muscle and nervous system. Emerging research suggests that vitamin D may also be significantly involved in other vital processes, such as signaling gene response, protein synthesis, hormone synthesis, immune response, and cell tumover and regeneration. A vitamin D receptor has been discovered within muscle, suggesting that vitamin D may have a significant role in muscle tissue function. This has raised the question of whether a FITNESS IN SOCCER Nutrition vitamin D deficiency would affect athletic performance and injury. Recent studies suggest that a vitamin D deficiency does indeed compromise athletic perfo1mance. It is estimated that as much as 77% of the general population of the United States rnay be deficient in vitamin D (serum vitamin D< 20 ng/ml), suggesting that athletes may have similar levels. Areview of studies ofvarious populations of athletes across the globe suggests a relatively high incidence of vitamin D deficiency (<20 ng/ml) and insufficiency (<32 ng/ml) in athletes worldwide. Furthermore, it has been suggested that in athletes with vitamin D insufficiency, supplementation with D3 may improve muscle strength. However, improvement in muscle performance (e.g., sprint times and vertical jumps) did not occur when serum leveis were normalized, but improvements were noted when serum vitamin D leveis rase above 40 ng/ ml. Thus, it has been recommended for athletes, such as soccer players, to monitor their vitamin D levels regularly and strive to maintain serum 25(0H)D levels > 40 ng/ml. To achieve this, a protocol for oral supplementation with 5000 IU of vitamin D3 per day is recommended. 4.10.3 Minerais In addition to selenium, whose role as an antioxidant has already been discussed, there are several minerais that are important for soccer players to include in their diets. Calcium is important for the growth, maintenance and repair of banes. It is also essential for muscle contractions, nerve conduction, and normal blood clotting. Zinc is involved in building and repairing muscle tissue, maintaining immune health, and the energy metabolism. Iron is an important component of the oxygen-carrying hemoglobin portion of red blood cells. When iron is deficient, the ability to carry oxygen to the cells diminishes and fatigue sets in. It therefore follows that a deficiency in sodium will also cause a drop in performance. Possible causes of iron deficiency include inadequate dietary intake of iron and inadequate total energy intake. Recovering from an iron deficiency can take three to six months. Sodium, potassium and chloride are the three major electrolytes. Electrolytes become ians in solution and have the ability to conduct electricity. In the body, they are important for the conduction of electrical nerve impulses and neuromuscular impulses. These three electrolytes are also important for maintaining fluid balance in and around the cells. While all of these are lost in sweat to some extent, sodium is lost in the greatest concentrations and therefore is the most important to replace during exercise. The amount of potassium typically lost during 90 minutes of play or practice is relatively small and can be replaced during recovery. While there has been recent debate in scientific research as to whether ar not sodium depletion results in muscle cramping, the personal experiences of many athletes and coaches convinces them that it does, at least for some athletes. Minerals are also best obtained through the diet. These are inorganic substances that have regulatory and structural functions in the body. Both vitamins and minerals are present in food to an adequate extent. Try to eat as varied a diet as possible to obtain all the different types of minerais and vitamins on a daily basis. FITNESS IN SOCCER Nutrítion FITNESS IN SOCCER Nutrition 4.11 WATERAND ELECTROLYTE BALANCE IN SOCCER PLAYERS ln addition to glycogen depletion, dehydration can be a significant source of fatigue for athletes. ln energy production, the largest portion of the chemical energy released is converted into heat. This heat has to be emitted through physical transfer, although the most significant partis discharged through perspiration. Although a higher ambient temperature is a hindrance because of the reduced physical transfer possibilities, the bigger concem is an excessively high level of humidity, because this makes sweating much more difficult. A soccer player's fluid loss can be described as follows: • Sweat production, which is a consequence of energy production, is determined by the intensity of the physical exertion. o Water Ioss through breathing is normally 200 ml per day, but it can be more in cases of dry air and high altitudes. o Urine production is typically 800-900ml per day. "Drink large quantities" is the motto here, and this needs to be taught on the training ground as some feel it to be bothersome. Gastric emptying also depends on the glucose content, with concentrated solutions remaining in the stomach for longer. An increase in osmolality slows down the emptying process, meaning that it is better to use glucose polymers, which lower the osmolality. Glucose absorption in the small intestine is an active energy process linked to the transportation of sodium. Water follows the osmotic gradient in a passive way. The assimilation of fructose is a passive process that proceeds more slowly and can give rise to osmotic diarrhea in larger quantities. Research has shown concentrations of CHO above 6% to slow gastric emptying. It has also been established that a combination of tvvo ar three different CHOs (sugars) are more rapidly absorbed than a single type. It is believed this is caused by the different monosaccharides being absorbed via different channels, so when there is more than one source of CHO in a sports drink, they can be absorbed simultaneously. The most important contributor to fluid loss is perspiration, which is an essential mechanism for thermoregulation. The evaporation of sweat cools the skin, helping to keep the core temperature within acceptable limits. It has been shown that relatively small fluid lesses (2% of body \veight) are sufficient to have a negative influence on performance. ln the event that fluid losses exceed 3%, there is clear evidence of a fall in V02max ln addition to water loss, there are electrolyte lesses associated with perspiration. Sodium lesses through sweat can vary considerably behveen individual athletes. While the concentration of NaCl is generally around 3-4g per liter of sweat, it is considerably hlgher in some athletes. Furthermore, tolerance to externai heat and internai heat production is reduced. 4.11.1 Sports drink No sports drink is ideal for everyone and all situations. A compromise has to be made betvveen proper rehydration and supplying as much energy as possible in the form of CHOs. Drinks should never be carbonated, however. The following factors are important in thls regard, and these are typically characteristic of sports drinks: Thirst can be a very poor indication of fluid deficiency, so players need to learn to estimate their lesses by, for example, determining their weight lesses at the training facility after severa! tough workouts. Fat contains less \Vater than muscles (i.e., 10% in fat compared to 75% in muscle), resulting in substantial differences betvveen the tvvo. It can generally be said that soccer players do not drink enough fluids, partly because drink breaks are not provided during the match. After a soccer match or equivalent training session, players are confronted \vith two significant negative phenomena. Firstly, they experience glycogen loss (see above), and secondly, fluid loss combined \vith limited salt loss. These can be restored in a combined manner. Fluid loss can be estimated based on weight loss and then compensated for by 150% (i.e., compensating for 1 liter of fluid loss by drinking 1.5 liters of fluid) to account for the resumption of diuresis. Preferably do not drink purified water, as this \Vill lower serum osmolality and stimulate diuresis, resulting in even greater fluid loss. It is better to drink a 4-6% CHO solution made from a mixture of glucose and glucose polymer (see sports drinks) \Vith 0.5-0.7g of sodium per liter. Be careful about consuming alcohol after a match, because alcohol also stimulates diuresis. It can also only be broken do\vn in the liver, therefore slowing down other metabolic processes in the liver, such as the formation of liver glycogen. Gastric emptying can constitute a challenge for soccer players and athletes in general. This emptying is determined by the volume and composition of the fluid ingested. The volume is decisive, and the emptying follows an exponential function, decreasing quickly as the remaining fluid drops. 1. The osmolarity (or osmolality) is the number of particles of a substance expresses per liter (osmolarity) or per kilogram (osmolality). Isotonicity says something about the quantity of particles in a solution, but not very much about the type of dissolved particles (e.g., sodium, potassium, CHOs, etc.). The blood has a tonicity of 290-300 mosmols and contains, in this regard, 0.9g of NaCl and 5g of glucose per li ter. Drinks \vith the sarne tonicity are referred to as isotonic solutions, while those with greater tonicity are described as hypertonic solutions, and those with lower tonicity are referred to as hypotonic solutions. An isotoníc sports drink therefore has an osmolarity comparable to that of plasn1a, and it is primarily a thirst quencher, providing \Vater and replenishing salt and CHO to a limited degree. The tonicity of a solution plays a role in the emptying of the stomach, the absorption via the intestine, the quantity of kcal in the form of CHOs, the supply of \Vater, and the supply of electrolytes, prin1arily sodium and potassium. The size of the dissolved particles (i.e., the type of CHO) and the quantity of sodiurn, as \vell as the quantity of CHOs, determine the tonicity. 2. Type of CHO present Only monosaccharides can be absorbed directly through the intestines, while other CHOs have to be first broken down by an enzymatic process. In the event of an immediate need for CHOs, glucose is the best solution, but if it is being administered for the purpose of glycogen recovery, slow CHOs (i.e., normal food) are better. FITNESS IN SOCCER Nutrition 4.11.2 Use of sports drink The characteristics of a sports drink will determine the best moment to use it: a. Before and during physical exertion: a solution of fast CHOs, such as dextrose, sucrose or maltodextrin. Maltodextrin, or dextromaltose, is a sugar obtained through partial hydrolysis of starch containing a particular quantity of free glucose. It is given a dextrose equivalent to indicate the quantity of free glucose. For example, pure starch has an equivalent of O, while it is 100 for glucose and lo>ver than 20 for dextromaltose. Its advantage lies in its lower osmolarity, because it is a larger molecule than other sugars. The terms "slow and fast CHOs" are relative, because other factors also play a part. For example, chocolate contains "fast" CHOs, but slower gastric emptying occurs because of the presence of fat. Much has also been said about rebound hypoglycemia. This was shown in a study once but not since, and it is very rare among athletes. b. Wíthin 15 minutes after the exertion, start rehydrating up to 150% of the quantity of fluid lost, initially with fast CHOs in an isotonic solution combined with a protein solution, such as low-fat chocolate milk. Follow this later with slow CHOs in the form of a normal meal. It is important to repair the structural damage through a combination of limited amounts of protein and CHO in a ratio of 15 kcal per 1 gram of nitrogen. c. Depending on the circu111stances, take an isotonic solution in the event of severe dehydration, such as from a tough match or warm environment. A hypertonic solution (300-500 mosmols) can be used in cold weather, but take care vvith this, because high tonicity can quickly lead to stomach and intestinal problems. d. Depending on the duration of the exertion: • < 1 hour: 6% solution 0 1-3 hours: 6% solution with 10-20 mg of sodium chloride 0 more than 3 hours: 6% solution with 20-30 mg of sodium chloride The presence of sodium improves the absorption of water and CHOs, prevents hyponatremia, inhibits urine production, and stimulates the feeling of thirst. ln this case, we also refer to recuperation drinks. FITNESS IN SOCCER Nutritíon 4.12 FOOD SUPPLEMENTS Food supplements can be dealt with very briefly: They are not necessary. lf a player feels tired, it is better to take a blood test before resorting to food or vitamin supplements. The blood analysis will clearly show where the deficiencies lay, so supplements can then be prescribed in a purposeful and effective manner. A normal, varied diet is sufficient, although vegetarians should consult the club physician. 4.12.1 Creatine An adult man weighing 80kg has approximately 130g of creatine reserves, mainly in the muscles (95%). An average of 2g is lost each day, although this is replenished through food intake. Creatine has often been misrepresented in recent years, with claims that it is tantamount to doping and a cause of cramps in soccer players. ln many cases, these accusations are the result of incorrect creatine regimes. It is not the intention here to either promote creatine ar advise against it. It is simply an attempt to put the ingestion of creatine into the right context. Creatine is available in food, and eating sufficient quantities of meat, fish and dairy products ensures that a large part of the creatine needed is ingested. For this reason, the most substantial effects of supplements are measured in vegetarians. The intake of creatine increases the CP reserves in the muscles. As already demonstrated above, these CP reserves are important for providing energy during short bouts of physical exertion lastingjust a few seconds. The ingestion of creatine speeds up the recovery of CP reserves. ln addition, maximum muscle strength is increased through the hormonal effect, with muscle relaxation also being improved. The long-term effects are not yet known. Although no negative effects have so far been established in the short term, creatine does result in an increase in weight dueto the buildup of fluid in the muscles. Seen in practical terms, creatine is a fairly expensive supplement. Nonetheless, the doses prescribed are often excessive. How should it be used? !. Quick charge for five days with 20-25g (for players weighing 65-82kg), taken over three daily doses at Sam, 3pm and 9pm together with 25g of sugar (e.g., Glucopur or dextra-maltose) dissolved in water. 7g three times with 25g of sugar 65 kg: 80-85 kg: 8g three times with 25g of sugar 2. After five days 65 kg: lg with 5g of sugar 80-85 kg: 1.2g of creatine with 5g of sugar Weight can increase by 1-2kg. Although other side effects, especially regarding the kidneys, are as yet unknown, it is wise to stop administering for 14 days after 6 weeks. ln the event of cramps, it might be possible to take magnesium in consultation with the club physician. Some players do not respond to creatine supplements. Because creatine can cause an increase in weight, performance may drop. Taking food supplements must therefore be done only in consultation with a sports physician. FITNESS IN SOCCER NutriHon 4.12.2 lron One of the effects of endurance training is an increase in plasma volume, which causes the blood volume to rise from 5 liters to 5.8 liters, for example. This results in a dilution effect because of the production of red blood cells not keeping up with the increase in plasma volume. The hematocrit can therefore decrease from the normal 42 to 39. This is referred to as pseudo-anemia, which, as the name suggests, is not really anemia but rather an advantage because of the work decreasing through the lower viscosity. The diagnosis is made by the laboratory in this case, with the ferritin normal. Real sports anemia is caused by disturbances in the metabolism of iron, caused by sports participation. A slight iron deficiency can already have significant repercussions for a player's fitness. The daily iron requirement is lmg for a man to replace losses through urination, defecation, and sweating, while 2mg are required for women because of menstruation. Intensive sports can disrupt Fe metabolism through malfunctioning absorption, increased loss, hemolysis anda poor diet. ln addition to factors specific to athletes, there are also other non-sporting-specific causes, such as giving blood, and these may not be compensated for by an athlete because of the mucosal block (see below), severe menstruation, or frequently occurring periods with small daily losses. The factors relating to athletes are: • Dietary mistakes: Following a weight-loss diet in which only 10-lSmg are ingested instead of the required 18mg per day. Westem food typically contains 5-6 mg per 1,000 kcal. • Red meat contains easily absorbable heme iron, but too little is eaten. • Frequent milk drinks convert bivalent into trivalent iron, which is useless. • lncreased hemolysis, especially when running and through repeated muscle contractions with damage to the red blood cells. • A number of physicochemical factors also lead to hemolysis, such as dehydration, acidosis, increased osmolarity, rises in temperature, higher catecholamine level, and peroxidation of the red blood cells through free radicais. Athletes have absorption disturbances in the area of the intestine: Endurance athletes absorb less iron because of apoferritin deficiency. They also have accelerated intestinal transit, meaning there is less time to absorb iron, and they exhibit what is known as a mucosal block (i.e., the absorption of ironis limited to 5-7 mg per day). Finally, athletes also have less acid in their stomachs, with the result that there is less bivalent iron. All these factors mean that athletes are more prone to iron deficiency. They need more iron than non-athletes because: • They lose more iron through their sport. • It is more difficult for them to absorb iron because of their sport. • ln particular, a relative iron deficiency is immediately significant for an athlete because of the rapid negative consequences for performance. There is a close connection between iron and hemoglobin and vo2m~x· A fall in the iron concentration leads to a decrease in V021n:ut which means a drop in the 0 2 supply to the muscles anda decline in the oxidative processes. This results in FITNESS IN SOCCER Nutrition inefficient use of substrate, faster lactate formation and reduced oxidative phosphorylation. The athlete's general capacity to perform therefore declines. A low iron level can be the cause of poor performance, so it is therefore useful to determine the ferritin levei three times per year. 4.13 RECOMMENDATIONS We can give a number of recommendations regarding food choices: 1. Alcohol is a non-nutritional food product. lt can only be broken down in the liver at an average rate of 150 mg per kg per hour, inhibiting the formation of glycogen and slowing down lactate elimination. It also has a diuretic effect and disrupts the fluid balance. 2. A diet must be varied and balanced with large proportions of fruits and vegetables, whole grains, and low-fat dairy products. The calorific value of food is usually underestimated, while the calorific cost of sport is overestimated. Kilocalories intake should therefore be calculated. Fat contains a huge amount of kilocalories. 3. Energy intake must be balanced against energy consumption. 4. Choose foods that give the appropriate energy balance while meeting the high energy needs of soccer. 5. Limit saturated fat (i.e., fat that is solid atroam temperature) to 10% of the kcal ingested per day. This particularly applies to animal fats in food products like cheese, full-fat milk, butter, ice cream, salami, mincemeat, and so on. Note that eating whole eggs does not appear to negatively affect serum cholesterol levels, and egg yolks are an excellent source of vitamin D. 6. CHOs are best obtained from fruits, vegetables and whole grains, with \vhole products being preferable to juices. During peak training season, however, \vhen CHO and energy needs are very high, sometimes drinking CHOs in the forro of juice or blended fruit smoothies can be a good strategy for meeting dietary intake goals. CHOs are absolutely essential given the limited glycogen reserves in the body and the dependence of the red blood cells, brain, and muscles on them. Candy is a poor source, as are added sugars. 7. For most elite athletes there is no need to limit dietary salt because so much is lost through perspiration. n FITNESS IN SOCCER j Nutrition FITNESS IN SOCCER Physical abilities and the role of aerobic jitness SUMMARY This chapter has conveyed to the reader the importance of nutrition in soccer. Good nutrition cannot replace talent, skill, or physical ability, but good nutrition enables a player to train to his maximum and to perform to the best of his ability on match day. A poorly fuelled player cannot express his technical and physical abilities on match day and is also more susceptible to injury. Adequate CHO intake is essential in order for a player to recovery quickly for the next game. Protein intake is also essential for repairing damaged muscle fibers. An adequate intake of vitamins and minerais is needed to support recovery and the immune systern. As we discussed in the previous chapter, U1e physical demands of the modern game are high, so it is important that the modem soccer player optimizes his nutritional strategies in order to cope with these demands. Good nutritional practices are also essential for the soccer player to cope with the demands of intensive weekly training, so that physical abilities can be improved. These physical abilities, and the importance of high-intensity interval training, are now discussed in the following three chapters. REl'ERENCES Alkin,on. f.S., foster·Powcll, K-, and Drnnd·Milkr, ].C., 2003. Diabetes Can>, 31 (12), pp. 2281-2283. Burkc, L, Louck,,A. and Broad, N .. 2006. Encrgy and carbohydmtc for lraining and n>covc'!)< J oi Sport.>Scicn<:e;<;, 2·1(71 pp.675.fiS5. Dunford M. cd., 2006. Sporb:< Nulrition:A l'ractm.' Manual for Profoooionals4lh cdition. Amcric.1n DiclcticsMooc. Du"'n, D.L., Shcrwood, R.J ., Czcrwlnski. S.A., Lcc, M., Choh, AC., Sicrvogd, R.M. and Chumlc.l, W.C., 2003. Dody Compo,ilion Mcthodo: Comparisons ,1nd Intcrp,.,,tation. J Diabetes Sei Tcchnol, 2(6), pp. J l39--ll·l6 Frankcníicld, D., Roth-You&ey, L. and Comphcr, C., 2005. Comparir.on ofprcdklivc cquation,' for n.-sting mcL1bolio rale in hcalthy nonobc.<;c and obcscadul\s; a sy1;tcrnatic rcview.J Am Dict ,\J;:;oc, 105(5). pp,775-59 Higgins, J.A., Higb<:e, D.R, Donahoo, W.T., Brown, t.L., Deli, I.L. and Bcs:;eom, D.H., 2004. Reoiwint slar<:h consumption pro motes lipid o~idation. Nutrition & l\ktabolir,m, 1(8). Hosscin·nczhnd,A- nnd Holick, M.F., 2013. Vilamin D for Hcalth:AGlobal Pcrr.pcctivc. MaynClin Proc, 88(7), pp.72(1.SS. jçnkin.,, M.A.,1995. Antioxídanlo ;md Fn.>c Rodicnh Sport:;!\lcd Web. hllp:/ /www.ric•H•du/-jcnky/~porW/un!iox.html Jellc, M., Sidney, K. and Blurnchent, G., 1990. Mct,,bolic Equivillcnlr. {METS) in ExcrcL<c Tcsting, E.l<crcisc Prescription, and Evalualion oi Functmnal Capadly. Chn. Curd1ol., 13, pp.555-565. Maf>&ey, L. K., 2003. Didary nnirnul and pl.1nl protcin and hurnan bane heulth: A wholc foods approach, Joumnl of Nulrilion 133: 8625-8655. 30 McArdl~, W., Katch, F.I.. and Ka1ch, V.L., 2012- Spor!Sand fu<cmsc Nutrition.·lth cdilion. fo!timo,.,, MD: \Vi!Hams nnd \\'ilkins. Ogan, D. and Pritchct~ K, 2013. Vitarnin D ,1nd thc Ath!etc; Rir.ks, Recornmcndalions, and Bcncfits. NutricnW, 5(6), pp.1&56-1B6S. Po,ilion oi thc Amcrican DicMk As.socialion, Dictitians of Canuda, and lhe Amcrican College of Sporlf., 2009. Medicine: Nulrition and Athklíc !'crfonnnnre.J Am DictNJ,;oc,109, pp.509·527. Schwellnus, M.P., o,.,,w, N. and Collins, M., 2011. lncrcased running SP"cd and P"'vious oamps rathcr than dehydration or scmm sodíurn drnng"'> P"'dict cxerci:><.~ar,socialcd rnusclc oamping: a ptOS!"'cliw cohort study in 210 Jronrnan triath!clcs. Dr j Sports Mcd, 45(8), pp.65!l-6. SjOdin, A.M., Forslund, A.H., We~ter!erp, K.R., Andersoon, A.6., Forslund, J.M. and Harnbraeus, 1..M., 19%. 111e infiucncc oi phye.ica! activily on BMR. Medicine ~nd Scicnre in Sporlnand Exercite, 28(1), pp.85·91. PHYSICAL ABILITIES AND THE ROLE OF AEROBIC FITNESS Jan Van Winckel, Werner Helsen, Bart De Roover, Steven Vanharen 5.1 INTRODUCTION The physical preparation of elite soccer players has become an indispensable part of contemporary professional soccer dueto the high fitness levels required to cope with the ever-increasing energy demands of match play (Carling et al., 2008; laia et al., 2009). Team sport athletes require a high level of aerobic fitness in order to generate and maintain power output during repeated high-intensity efforts. A well-developed levei of aerobic fitness also helps to recover quickly between these high-intensity efforts (Bishop and Spencer, 2004), This ability to recover between bouts of high-intensity activity and subsequently repeat these efforts is a criticai physical ability of the modern-day soccer player (Gabbett and Mulvey, 2008). The amount of high-intensity exercise carried out accounts for about 15-19% of the total distance covered and 10-15% of match play (Stone and Kilding, 2009). Although 60% of the time between consecutive high-intensity actions across match performance is spent walking, evidence shows that per game, top-class soccer players perform 150-250 intense actions (Mohr, Krustrup and Bangsbo, 2003), with a high-intensity action every 72 seconds (Bradley et al., 2009). Based on the physical demands and characteristics of team sport competition, and the potential importance of aerobic fitness, it is clear that a significant portion of the conditioning programs for soccer players should focus on improving their aerobic fitness in order to repeatedly perform high-intensity exercise bouts and recover adequately between these bouts (Stone and Kilding, 2009). Aerobic fitness measurements such as maximum oxygen uptake (V02rn,,) and the anaerobic threshold may also discriminate between players of different competitive leveis (St0len et al., 2005), so soccer training programs should regard aerobic conditioning as an important part of the seasonal training plan (Impellizzeri et al., 2005). 1 73 ~ 5.2 PHYSICAL ABILITIES We have adapted the classification developed by Steinhofer (Steinhofer, D., Leistungssport, Vol. 26, No. 6, 1993) to define the various physical abilities and the corresponding training methods. This classification will be used throughout this book to set up training plans. ,,::r - ~ ~~ ?i' m " - V> V> " -z !? ::: VI ''"o ~n Methodical Physical ability Training Training Methods Abbreviation Volume (min) Characteristics Repetitions lntensity (average velocity) lntensity (HR.n) % lntensity {V02mn) Work/ rest % ratio "~ n m ""~ "' ~ Long slow dis- tance Aerobic Endurance Continuous principie (without recoveries) Continuous extensive LSD ConE .Q, Long sfow distance. Uninterrupted low load intensity high volumes 60- 100 1 60 60 40 8/1 Uninterrupted low to medium load intensity high volumes 15 - 30 1-4 70 70 58 5/1 Variab!e endurance method CV Unplanned intensity changes 30-45 1-3 60-100 60-100 40-100 5/1 Fartfek variable method Fa Systematic intensity changes 30-45 1-3 60-100 60-100 40-100 5/1 8-15 3-5 75 75 65 3/1 Continuous intensive Conl l .,,,;;· High intensity, medium volumes :; ffi Tab/e 5. 1: Aerobic endurance and the different training methods Physical ability Methodical Training Training Methods Abbreviation Characteristics Volume (min) Repetitions lntensity (average velocity) lntensity (HRmax) '% lntenslty (V02ma•) % Worklrest ratio lnterval method {Medium to intensity, medium to high volumes) Anaerobic endurance lnterval principie (incomplete recoveries) vo=, lnterval v02tnt High intensity, high volume 5-8 6-12 85-90 85-90 75-83 2/1 Long interval loads Lint 2 to 5 minutes 3-5 5-8 90-95 90-95 83-90 2/1 Medium interval loads Mini 1 to3min 1-3 8-15 90-95 90-95 83-90 211 Short interval loads Sint 15sto1min 10-20 90-95 90-95 83-90 211 3060sec ~ VOZm:;,, repetition V0 2Rep Long repetition load LRep Medium repeti!ion Short repetition !oads 4 6-12 85-90 90-100 83-100 211 2min 2-3 3-5 90-95 95-100 90-100 211 MRep 1 minto2min 1-2 8-12 90-95 95-100 90-100 211 Srep 15sto 1min 8 tot 10 90-95 95-100 90-100 211 Table 5.2: Anaerobic endurance and the different traíning methods 1560sec [ §. Repetition method (High intensity, limited to low to medium volumes) High intensity, high volume ';;; "'~ ~ :;. .,, ~ ~ :s Q .,, ~ V> V> .Q_Z m Q .,. z (:;' VI .,,, o :; n .,, n "'m "' "' ""' 76 1 FITNESS IN SOCCER FITNESS IN SOCCER Physical abilities and the role of aerobíc fitness 5.3 AEROBIC FITNESS Ahigh level of aerobic fitness is important for the modern-day soccer player. Ahigh vo2max has been correlated with work-rate during a game and is reported to aid recovery during high-intensity intermittent exercise (Reilly, 1997). An increase in the capacity of the 0 2 transport system leads to a higher aerobic contribution to the energy expended, taxing the anaerobic energy system less and subsequently reducing fatigue by saving glycogen and preventing decreases in muscle pH (Impellizeri et al,. 2006). Helgerud et ai. (2001) concluded that enhanced aerobic fitness in soccer players improved their performance by increasing the distance covered (20%), enhancing work intensity, and increasing the number of sprints (100%) and involvements with the ball during a match (24%). This study found a 10% increase in V02max after the addition of 20 specific training sessions to a normal soccer training regime in 10 weeks, a finding reproduced by McMillan et al.(2005). A reduced attention to aerobic conditioning during the competitive season, in some sports, suggests that the importance of aerobic endurance may be underrated. This · may be warranted in some instances, such as if other aspects (technical or physical) are shown to be more important. Accordingly, it appears that coaches, along with strength and conditioning professionals, prioritize training regimens that focus on improving anaerobic fitness during the competitive season. This is most probably because high-intensity activities are associated with important game-winning situations, such as scoring points in basketball or scoring a try in rugby union. However, it should be emphasized that a lack of aerobic conditioning is also very likely to influence the ability to repeatedly perform, and recover from, high-intensity activity (e.g., sprints), so the absence of aerobic conditioning during the competitive season, regardless of sport, may not represent best practice in terms of optimizing the condition of athletes (Stone and Kilding, 2009). Continuous extensive and continuous intensive training drills train soccer players to be able to sustain 90 minutes of competitive match play. These drills particulary invoke beneficial peripheral (muscular) adaptations in soccer players, but also are of benefit to the cardiovascular (central) system. For example, these training drills increase muscular capilliarisation and increase the concentration of specific intra-muscular enzymes that helps the player to burn more fats during match-play, therefore crucially preserving muscle glycogen stores. Some examples of these training drills are now presented in a soccer-specific manner. Physical abi/ities and the role of aerobic fitness 5.4 5.4.1 SOCCER-SPECIFIC TRAINING DRILLS USING THE CONTINUOUS PRINCIPLE Continuous extensive Explanation: Create hvo diamond-shaped formations next to each other with a minimum of six players. The positions of the cones can be position specific. Player Xl plays to player X3, who sets the ball to player X2, \Vho then plays to player X4. Player X4 dribbles with the ball toward the starting position XS on the other side. Progression XI -X2- X3- X4- XS- ... Variation: Player Xl plays to player X2, who sets it back to Xl. Player Xl passes to player X3, who sets it back to player X2, \Vho then plays to player X4. Explanation: Xl passes to X2, who receives, turns, and then plays the bali to X3. X3 passes to X4, \vho receives the bali and plays the ball to the GK using the inside of the foot and keeping the ball lo\v. After finishing, X4 dribbles back \Vith the bali, performs a SAQ exercise as indicated, and begins a new exercise at the other side to ensure both feet are being used. Variations 0 Xl passes to X2, lvho plays back to Xl. Xl then plays to X3, \vho receives, turns and plays to X4. X4 shoots the ball into the hands of the GK. o Xl passes to X2, 'vho plays back to Xl. Xl then plays to X3. X3 plays back to X2, who passes to X4. X4 then finishes by putting the ball in a comer of the goal. 0 XI passes to X2, who plays back to XI. XI then plays to X3. X3 plays back to X2, \vho passes to X4. X•l then puts the ball back to X3, rnaking a feint before receiving the ball again frorn X3 and finishing in a Ivl situation \Vith the GK. o Integration of defenders. Comments 0 Passing quality o Continuous running exercises Progression XI - X2- X3 - X4- XS- X6- X7 - XS FITNESS IN SOCCER FITNESS IN SOCCER Physical abilities and the role of aerobic fitness Physical abílíties and the role of aerobic fitness Explanation . . . Positions can be changed and the pass1ng direction can also be altered. The exercise starts with a thro\v from the goalkeeper ora pass from the coach. Variations o Different passing directions. o Different formations Progression Stay in position or rotate: Xl-X2-X3-X4-X5-X6-X6-Yl-Y2-... 5.4.2 Continuous intensive Explanation Xl plays to X3, who then plays the bali to X2. X2 plays the bali to X4, \vho puts the ball, over the ground using the inside of the foot, to the GK. After finishing, X4 returns down the middle and begins a nelv exercise at the other side, so both left and right sides are practiced. Variations o Xl to X2, X2 to Xl, XI plays to X3, X3 to X2, \vho then plays the bali to X4, lvho receives, turns and shoots into the hands of the keeper, still with a controlled shot. o XI to X2, X2 to XI, XI to X4. X4 plays to X3, \vho then dribbles and shoots on goal. If desired, X3 can make a skill movement before finishing. o Integration of defenders. Explanation: Xl plays to X2, \vho then plays to X3. X3 takes the position of X4. Variation 0 Xl passes to X2. X2 passes to Xl, and Xl plays to X3. 0 Xl passes to X2. X2 passes to Xl, who plays to X3. X2 then puts (passive) pressure on X3, and Xl asks for the ball on the inside or outside for a 1-2. X3 then has the option to take on the defender and go past X2 or engage in a 1-2 with Xl. 0 Xl to X2, \vho sets it back to Xl. Xl plays to X3, \Vho does a 1-2 \vith X2. Progression: Xl-X2-X3-X4-XS-6-Xl Progression: 0 Playing to the goalkeeper with inside of the foot. 0 Playing into the goalkeeper' s hands • Playing to the corners \Vith the inside of the foot. 0 Normal finishing to score a goal. Comment Adapt distances to the objective of the periodization and the number of players. Progression Xl-X2-X3-X4 1 79 801 FITNESS IN SOCCER FITNESS IN SOCCER Physical abilities and the role of aerobic fitness Physical abilifies and the role of aerobic jitness Explanation pJayer Xl plays the ball to X2. Player X2 plays the ball straight back to player Xl. Player Xl receives the ball and passes to X3, and player X3 plays straight to X2, ,vho passes back to X3. X3 receives and plays a long bali to XS. The sarne exercise is then started on the other side with another bali. After X3 has kicked a long ball, he has a ball played to him by the coach and finishes in one or hvo touches. He then runs to position X4. Explanation The game is played 10v10 on the field with one neutral player of each team on both sides of the pitch. The neutral players have to play the ball back into the game while using a maximum hvo touches and then change position \Vith the player he received the ball from. The aim is to get width into the game. Variations 0 The neutral player gets the bali, puts it back in the game \vith one touch and then changes positíon. • The neutral player receives the ball and is obliged to dribble into the field before playing the ball to one of his teammates (decision making). • Sarne as variation 2, but when dribbling into the field, his third touch of the ball needs to be a pass (speed of execution). • Variation in the number of touches. • Variation in how to make goals (one touch, keep possession after goaL .... } • If you \vant to bring depth in the game, you can put the neutral players between the small goals. Explanation The game is played using lüvlü in the middle of the pitch. Each player is given a particular number. The coach calls out four numbers each time. These players have to Ieave the box as quickly as possible, run around one of the sticks surrounding the pitch, and return to their positions as quickly as possible. This means there are six playing against 10 every time the coach calls four numbers from the sarne team. • A:i t1 ., Comments Emphasize the movement of the neutral players along the side of the field. They need to participate in an active way and anticipate the changing positions of the players in the field. Comments o Various passing configurations are possible. o The exercise is best started off with one ball Progression X2-Xl-X3-X4 Explanation The play starts with a dribble by Xl. Xl plays the ball to X3, 'vho plays to X.2. X2 then dribbles inside and plays to X4, who receives, turns, and plays the bali to the other side (to XS). After X4 has given the pass to XS, the GK thro\VS a bali to\vard X4, which he has to contrai nnd finish. Sarne exercise at both sides lvith both groups working simultaneously. The coach gives a signal \vhen the next players can begin to coordinate and control the intensity. ... • Variations • You can vary the amount of numbers you call from each team, so the teams play against each other in different numbers, changing the intensity each time. 0 When calling the nurnber of a player, you can add the nurnber of a specific cone around \vhich they have to run, as \Vell as the direction {Left/Right) (different distances}. o Numbers can be paired, so players from both teams have to leave the box. • Play one or hvo touches. t Comments o Players can be set up in a normal playing system. o Assistant coaches can control offside rule. Variations 0 Xl to X3, who plays it back to Xl. Xl to X2, who dribbles inside and plays to X4. X4 puts it back to X2, \vho gives a long bali to XS. o Xl to X3, ,vho puts it back to Xl. Xl to X.2, \vho puts it back to X3. X3 plays to X4, \vho plays it back to X.2. X2 gives the long bali to XS. o Integration of defenders. Comments • Various passing configurations are possible. 0 The exercise can be started off vv·ith one ball Progression Xl-X3-X2-X4-XS-X6-X7-X8 sz FITNESS IN SOCCER f ITN ESS 1N SOCCER I Physica/ abilities and the role of aerobic fttness High-intensity interval training SUMMARY Both low-to-moderate-intensity "extensive" soccer exercises and more intense, but shorter, "intensive" soccer drills are important to improve soccer-specific fitness. Continuous extensive games (e.g., 4 x 20 minute bouts of 11v11 on a full-size pitch) train the soccer players' capacity to complete 90 minutes of competitive match play. More intensive soccer drills of shorter duration (e.g., 8 x 4 minute bouts of 4v4 small-sided games) train soccer players to play at a high intensity and cope with the demands of an intensive period during a game. High-intensity interval training is discussed in the next chapter. HIGH-INTENSITY INTERVAL TRAINING (WITH SPECIAL REFERENCE TO SMALL SIDED GAME PLAY) Kenny McMillan, Jan Van Winckel, Guido Seerden, Werner Helsen 6.1 INTRODUCTION TO HIGH-INTENSITY INTERVAL TRAINING (HllT) Interval training can be defined as a single or repeated interval of sport-specific exercise with no additional resistance (Paton and Hopkins, 2004), \vhile high-intensity training refers to exercise performed above the second ventilatory threshold (Seiler and Kjerland, 2006). Because training at high intensity puts a high strain on the player, high-intensity training can be organized through interval training. Interval h·aining at high intensities (i.e., just below or around V02 ma) improves endurance performance through improvements in all of the three components of the aerobic system: V0 2max' anaerobic threshold, and running economy. REFERENCES Bishop, D. and Spencer, M., 200-1. OQlNmirmits of rcpcalcd·sprint ability in wdl-train~d tcam+port athlclcr. and cndurnnc1-~trilincd uthlctcs.J Sports Mcd Phys Fitnoso, 4·1{1), pp.1•7. !lri!dlcy, P.S., Sheldon, W., Woostcr, !I., Oloen, P, Boana5, /'. and !<ru<lrup, !'., 2009, High-lnlcmity running ln FA P"'mier l<eaguc ~,occcr mntdic". joumal oi SportsSdcncc3, 27, pp.15<J-16S. Gabktt, T.J. and Mul,·c;~ M.J ., 2003. Time-motion analysis of small·r.idcd lrnlning gümcs and compctilion in dite womcn r.occcr playcm. Joumal ofStr<.'ngth and Conditioninz Rcocardl, 22, pp.S.H-552. Hclgcrud )., Wir.lofi, U., Engcn L. and Hofi, J. (2001) Acrobic cnduran<'<' lraining imprm·cr. socccrpcrformancc. Medicine and Sdcncc in Sporls nnd facr<:i!W, 33:11, pp.1925-1931 tmpdhzcri, F.M., Rampinini, E. und Marcora, S.M., 2005. Physiologkal a5"cssmcnt of acrobk training in socccr. l Sporls Sei, 23(6), pp.58.3-92. Jmpcllizzcri, F.M., Ma reora, S.M., Cilc.tagna, C., Rdlly, T., Sa%i, A.faia, F.M., 2006. Pliysiological .lnd pcrfom1ancc dfects of gcnclic ''C!'Jur. spcciflc acrobic training in wcccr playcm. lntcmationnl joumal of Sports Mcdidnc, 27, ppA83-192 McMilfan, !<., Helgerud, /., Macdonald, lt, nnd Hoff, J.,2005 Phy$iologka! adapti!IÍO!l.' \o •occcr·opccific endurnn<:c training in profc,:sional youth "'"'"'' playcrs. Br JSports Mcd 39; pp.273-277. Mohr, M., Krustrup, P. and füngsbo,J., 2003. 1'.fatcli pcrformnnreofhigh+tandard soc<'<'r pfoyers with spcdal .,,[c.,,ncc to devclopmcnt of fatigue.Joumal of SportsScicnres, 21, pp.519-528. _ _ Reíl!y, T., Atkiru;on, G. and Waterhousc J., 1997. Travd fatigue and jct-lag.J Sports Sci., 15(3), pp.365-9. Stnlcn, T., Chama ri, K, C.1stagnn, C. and Wislolf, U., 2005. Phy~io!ogy ofScx:<:cr.An Update. Sports Me, 3~, pp.501-536. Stonc, N.M. and !<ilding, A.E., 2009. Acrobic Condilioning for Tcam Sport Athlcles. Sports Mcd, 39(8), pp.615-6-12. HIIT (High-Intensity Interval Training) may consist of high-intensity workloads J (> 85% V02 m 11 executed for a short duration (between 30 seconds and 4 minutes) interspersed with recovery times in between each exercise bout (usually in a 1:1, 1:2 or 2:1 ratio). HIIT can be traced back to as long ago as 1912, when the Finnish Olympic long-distance runner Hannes Kolehmainen was reported to be using interval training in his workouts (Billat, 2001). Severa! years later in the 1930s, the German professor Dr. Woldemar Gerschler further developed interval training at the University of Freiburg. Gerschler teamed up with cardiologist Dr. Herbert Reindel, and together they developed a training system consisting of running intense but short distances followed by brief recovery "intervals" (Sears, 2001). Gerschler did not allow a runner to begin the next repetition until the HR had retumed to 120bpm (Jenkins, 2005). FITNESS IN SOCCER 1 FITNESS IN SOCCER High-intensity interva/ training High-intensity interval training Today, HIIT is regarded as one of the most effective means of improving the physical performance of athletes (Buchheit and Laursen, 2013a). Indeed, in already welltrained athletes, the supplementation of high-intensity training on top of an already high training volume seems to be extremely effective (Laursen, 2011; Laursen and Jenkins, 2002). Various studies have shown the significant effects of HIIT in as little as 2-3 weeks (Acton-jacobs et ai., 2013; Bogdarus et a!., 2013; Buchan et ai., 2013; Tjonna et ai., 2013; Boyd et al., 2013). Scientific research on the optimum length of high-intensity intervals is equivoca}, although positive results have been found with various interval lengths ranging from 30 seconds up to 4 minutes (Little et al., 2010; Esfatjani and Laursen, 2007; Laursen et ai., 2002; Billat et ai., 2000; Smith et ai., 1999). With regards to the training intensity, scientific research demonstrates that sub-maximal (i.e., 90-95% V02 ) (Zuniga et ai., 2011) or maximal intensities (100% VO 2m~x ) (Bishop et ai., 2011) eli~it the greatest adaptations. ln their review on HIIT, Buchheit and Laursen (2013a) suggest that maximal ar close to maximal intensities are the most effective at increasing aerobic capacity because they stress the oxygen transport system the most, activate more and larger motor units of muscle fibers, and are performed at near maximal cardiac output. While there is evidence that there are still benefits to be gained from HIIT training programs using lower intensities (Boyd et al., 2013), the most profound benefits are realized at higher intensities (Acton-jacobs et ai., 2013; Boyd et ai., 2013; Cicioni-Kolsky et ai., 2013; Moholdt et ai., 2013). When examining the effect of training intensity distribution on aerobic fitness variables in elite soccer players, Castagna et al. (2011) reported that even though almost two-thirds of players' training time was spent at low intensities, only the time spent at high intensity (90% of HRmn) was related to changes in aerobic fitness. Impellizzeri et ai. (2005) reported similar findings and demonstrated a significant correlation between time spent in high-intensity zones and changes in oxygen uptake at lacta te threshold. These results highlight the effectiveness of high-intensity training in soccer. It is believed that an optimal stimulus to elicit both maximal cardiovascular and peripheral adaptations is one where athletes spend at least several minutes per session in their "red zone," which generally means reaching at least 90% V0 2m.•x (Buchheit & Laursen, 2013b). High-intensity training that raises the HR to above 90% of HR should constitute at least 7-8% of the total weekly training plan for elite soccermPlayers during preseason and in-season (Castagna et al., 2013). 6.2 HllT EFFECTS ON CARDIOVASCULAR ANO MUSCULAR ADAPTATIONS The cardiovascular and muscular adaptations to HIIT are summarized in the table below. Effects of High lntensity lnterval Training Cardiovascular adaptations lncreased cardiac muscle capillary density Lowered HR at similar pre-training work levels lncrease cardiac efficiency and the maximal mitochondrial capacity of the heart . .. (Hafstad et ai., 2011 ). lncreased stroke volume (Helgerud et ai., 2007) Lower blood lactate levels for a given work intensity lncreased left ventricle volume and increased contractibility (Slordahl et ai., 2004) lncrease in V0 2max (Oaussin et ai., 2008) . ... . Muscular adaptations lncreased transcription and biogenesis of mitochondria in the skeletal muscle cells of highly trained athletes (Acton-Jacobs et ai., 2013) lncrease in mitochondria (number and size) (Gibala, 2009) lncrease in maximal activities of mitochondrial enzymes in skeletal muscle (Kubekeli et ai., 2002; Laursen and Jenkins, 2002) lncreased proportion of Type lla fibers (Billat, 2001) Optimized oxidative phosphorylation lncrease in oxidative enzymes (Burgomaster et ai., 2008) Activation of PGC-1 a via AMPK pathways lncrease in fat oxidative capacity (Talanian et ai., 2007) lncrease in GLUT4 and glycogen Table 6. 1: OveNiew of the effects of HllT 6.3 LACTATE FORMATION DURING HllT During oxygen-independent glycolysis, glucose/ glycogen molecules are processed and broken down inside the muscle cells. Each molecule of glucose is broken down to deli ver ATP, and two molecules of lactic acid are produced (a proton and lacta te). Many coaches still believe that lactate is a metabolic dead-end only formed under anaerobic conditions, with lactate playing the role of the toxic by-product. This oxygen-independent glycolysis works continuously (even during rest) and not only when sufficient oxygen is unavailable (Brooks, 1986). All energy systems are, to a greater ar lesser extent, active ali the time, and their contributions depend on the energy requirements and therefore the intensity and duration of exercise. The levei oflactate found in the blood and muscles is the difference behveen lactate produced and lactate processed. At some point of increasing intensity, lactate production will become higher than lactate clearance. ln the past, this was referred to as the anaerobic threshold or the Onset of Blood Lactate Accumulation (OBLA). We use the term lactate threshold in this book. This lactate threshold is determined not just by lactate production but also by the ability of muscle cells to remove and process lacta te. If lactate levels accumulate, as may happen during HIIT, glycolysis is inhibited and the muscle fiber fatigues dueto the protons associated \vith Jactate ians. 85 FITNESS IN SOCCER High-intensity interval trainíng FITNESS IN SOCCER High-intensity interval training 6.4 LACTATE CLEARANCE DURING HllT Lactate can be cleared via two mechanisms. It can be metabolized back to pyruvate and processed in the muscle cell by oxidative phosphorylation, which is an oxygen-dependent process. On the other hand, lactate can leave the muscle cell through the cell membrane. It may then be absorbed and utilized in oxidative metabolism by other muscle cells within the sarne muscle, ar it may leave the muscle and enter the circulation system. Once in the circulation, lactate can be: o Transported to other skeletal muscles where it can be stored o Used by the heart for oxidative energy production • Transported from the peripheral tissues to the liver by means of the Cori CycleL where it is then reformed into pyruvate through the reverse reaction using lactate dehydrogenase e Transported to the brain for oxidative energy production. The lactate shuttle, which describes the movement of lactate intracellularly and intercellularly (cell to cell), was hypothesized by Dr George Brooks in the 1980s. This theory states that lactate produced at sites with high rates of glycolysis and glycogenolysis can be shuttled to adjacent or remote sites, including the heart and other skeletal muscles, where the lactate can be used as a gluconeogenic precursor or substrate for oxidation (Brooks, 2009). During HIIT, fast-tvvitch fibers begin producing lactate at high rates. Because fast-hvitch fibers are not built well for oxidative phosphorylation, lactate is emitted and subsequently picked up by slow-tvvitch fibers, which are better equipped for oxidative phosphorylation, or the circulatory system may carry it to the heart, the liver, the brain or less active muscles. 6.4.1 Monocarboxylate transporters (MCTs) and HllT Monocarboxylate transporters (MCTs) are proton-linked plasma membrane transporters that carry molecules having one carboxylate group (monocarboxylates), such as lactate and pyruvate, across biological men1branes. In the literature, at least 14 MCTs have been identified, although MCTl and MCT4 seem to be most relevant to lactate and pyruvate transportation 1vithin cardiac and skeletal muscle (Bonen, 2001). MCTl and MCT4 have been identified as H+ /lactate symporters capable of mediating the bidirectional transport of lactic acid across the plasma membrane (Halestrap and Meredith, 2004). MCTl is the most important MCT for endurance athletes because it is the key lactate mover in muscle cells. Slow-hvitch muscle fibers in particular have relatively large amounts of MCTl in their membranes. The presence of large quantities of MCTl in slow-twitch fibers and cardiac n1uscle cells demonstrates that MCTl is probably responsible for clearing lactate to cells that are better equipped for oxidative phosphorylation. Unlike MCTl, MCT4 is more common to fast-twitch muscle fibers, suggesting that MCT4 is better equipped to transport lactate out of the muscle cell. Exercise training can increase the expression of both MCTI and MCT4 in muscle cells, and this effect is related to the intensity of training. MCT4, like other glycolytic enzymes, is up-regulated by hypoxia. This adaptive response allows the increased lactic acid produced during hypoxia to be rapidly cleared from the cell (Ullah et ai., 2006). Although the research into MCTs is still in its infancy, it can already be concluded that lactate processing can be improved through appropriate training. To improve lactate clearance and processing in soccer players, training at fluctuating high intensities (i.e., HIIT) is necessary. During soccer-specific HIIT for example, Iactate is produced, and during recovery intervals, the body is trained to efficiently utilize and clear the lactate. Therefore, HIIT is important to improve MCT concentrations, lactate processing, lactate clearance, the lactate threshold, and performance capacity. 6.5 HIGH·INTENSITY INTERVAL TRAINING VERSUS LOW·INTENSITY CONTINUOUS TRAINING Both HIIT and low-intensity continuous training are important in impro~ing aerobic fitness. The main goal of interval conditioning is to induce a greater training stimulus at intensities higher than what would be tolerated in a single bout of continuous exercise (Wenger and Bell, 1986). Continuous lo1v-intensity training recruits predominantly slow-hvitch motor units, while HIIT will recruit additional fast-twitch motor units for relatively short durations (Enoka and Duch, 2008). The cardiovascular adaptations that occur with HIIT are similar, and in some cases superior, to those that occur with continuous endurance training (Helgerud et al., 2007; Wisl0ff, Ellingsen and Kemi, 2009). Moreover, HIIT can often produce a broad range of physiological effects in less time than high-volume low-intensity continuous exercise (Londeree, 1997; Daussin et al., 2008; Psilander et al., 2010). This may be because the time course for performance improvement with increases in training volume may not occur as rapidly as when using acute increases in high-intensity training (Laursen et al., 2002; Laursen, 2011). Ho1vever, some important physiological adaptations occur in response to Jo;v-intensity continuous training that are not observed with HIIT (Laursen, 2011). For instance, Ingham et al. (2008) demonstrated that a low-intensity continuous training group improved their speeds at lactate threshold to a greater extent than the mixed-intensity training group. It is often purported that these periods of relatively low intensity and high training volumes may provide the "aerobic base" needed to facilitate the specific adaptations that occur in response to HIIT (Laursen, 2011). The periodization of continuous extensive soccer drills (e.g., 2 x 15 minutes of 9 v 9 play at an intensity of 70-75% of HR 0 . , ) and higher intensity "intensive" drills (e.g., 6 x 4 minutes of 4 v 4 small sided game play play) throughout the soccer season is discussed in Chapters 14to18. ss FITNESS IN SOCCER I High-intensity interval training FITNESS IN SOCCER 1 High-intensity interva/ training 89 6.6 HIGH-INTENSITY INTERVAL TRAINING WITH OR WITHOUT THE BALL ln soccer, two different conditioning methods are usually used to improve fitness: conditioning exercises without the ball and conditioning exercises with the bali. Conditioning exercises using the ball are being increasingly implemented in soccer practice (Hoff et al., 2002; McMillan et al., 2005). The main advantage of skill-based conditioning games and exercises over traditional interval training without the ball (e.g., generic running drills) is that they also provide the opportunity to develop decision-rnaking and problem-solving skills while under stressful physical loads (Gabbett, 2001). Moreover, soccer-specific conditioning drills such as small-sided games (SSGs) may be slightly more strenuous than traditional training approaches (Impellizzeri et al., 2005). These higher responses in soccer players may be attributed to use of the ball, which increases the metabolic cost of performing any given activity (Little and Williams, 2006; Kelly and Drust, 2009). The motivation and enthusiasm of players may also be greater when engaging in soccer-specific conditioning games and dri11s (Stone and Kilding, 2009). 6.6.1 Generic continuous running drills 25m 30m 6~ ' ~ } "" '. } tom } lOm 6 6~ 55m } !Om .ó.B: 15 m !Om J <E·,.··································· START Fig. 6. 1: The "Hoff track" used for soccer-specific interval training. Hoff and Helgerud (2004) argue that continuous interval training for 3-S min using a working intensity of 90-95% of HRmnx should eleva te V02max of soccer players by enhancing stroke volume and thereby increasing cardiac output. Hoff et al. (2002) designed a soccer-specific dribbling track (Hoff track) for this purpose, and they reported that this form of interval training resulted in physical loads equivalent to 94% HRmax and 92% V02ma-"' which are optimal intensities for developing aerobic fitness (figure 6.1). When using the Hoff track to conduct 4 x 4 minute intervals at 90-95% of each players HRm,>1 McMillan et al. (2005) increased the average V0 2max of the Celtic FC U-18's squad by approximately 10% in only 10 weeks. Two intervals sessions were performed per week in addition to the normal soccer training regime. Importantly, by using the Hoff track soccer players can improve their aerobic endurance in a safe and controlled manner, due to the low number and magnitude of accelerations and decelerations involved (low neuromuscular load), and of course a lack of tackles and body contact. When using SSGs for fitness training, there is always the risk of injury due to lots of twisting and turning movements, mistimed tackles and body collisions. 6.6.2 Generic intermittent running drills Soccer coaches can also prescribe high-intensity intermittent drills to improve anaerobic and aerobic fitness. Generic running drills involving short exercise times and recoveries (e.g., lSs running:lSs recovery and 30s running:lSs recovery are typical examples). Work-rest ratios, running velocity, accelerations, decelerations and changes of direction can all affect the intensity of these drills. Running at intensities dose to ar just over the velocity at V02m,,, (vV0 2m,J for a period of 5 - 8 minutes is an example of a generic intermittent running drill that would serve useful to soccer players. The running velocity at the end of the 30-15 Intermittent Fitness Test (vIFT) as described in Chapter 7 is an example of an individualized running velocity that can be used to design and implement effective generic intermittent running drills to improve a soccer player's endurance capabilities. Since the main scope of this chapter is on high-intensity SSG play, the readeris referred to the excellent work of Buchheit and Laursen (2013a; 2013b) for a comprehensive overview of such drills and the physiological adaptations they manifest. One of the main advantages of using generic running drills to improve the endurance capabilities of soccer players is that intensity can be easily controlled and individualized for each player. For example, when using the Hoff track, each player runs at his own individualized 1unning speed to keep his HR at behveen 90-95% HRmux· Another example vvould be a squad of players all performing intermittent running at 90% of their vV02 m,,,, ar vIFT. FITNESS IN SOCCER flTNESS IN SOCCER High-intensity interva/ training High-intensity interval training 6.7 SMALL·SIDED GAMES (SSGs) Recently, many people have tried to rediscover the usefulness of SSGs within soccer fitness training (Aguiar et al., 2012; Clemente et al., 2012, Hill-Haas et al., 2011). SSGs have the benefit that they reproduce the movements, technical conditions, and physiological intensities of a real soccer game (Gamble, 2004; Ovven, 2003; Gregson and Drust, 2000; Little, 2009) 1vhile simultaneously obliging players to <leal with pressure and decision making in a fatigued status (Gabbet and Mulvey, 2008). They also help players to develop their technical and tactical skills within a realistic game situation. Research has shown that athletes regard match-like training sessions to be the most important practice activities for improving performance (Singer and Janelle, 1999; Hodges and Starkes, 1996; Starke et al., 1996; Helsen, Starkes, and Hodges, 1998). Moreover, SSGs also increase the players' motivation and compliance when compared to traditional fitness training sessions because they find them more sport specific (Gregson and Drust, 2000; Little, 2009). Due to the interaction between technical ability, tactical skills, and the physical component, the use of SSGs can be more time efficient as these three factors can be trained alongside each other (i.e., concurrent training) (Gregson and Drust, 2000; Little, 2009). Nevertheless, this depends on the specific game format. Some variables affect the exercise intensity, tin1e-motion characteristics, and technical load. Coaches try to change the training stimulus by altering variables such as: 0 the size of the pitch o number of players involved 0 use of goalkeepers 0 type of ball possession o goal orientation 0 tactical obligations 0 coach encouragement 0 training regímen 0 players' characteristics Fig. 6.2: The factors influencing the intensity of a small-sided game. It is hard not to get lost within the massive amount of research data, so presented below is a brief overview together with some practical implications of the different types of SSGs and the effect they may have on the acute physiological responses of the players, as well as long-term physiological adaptations. 6.7.1 Pitch size Increasing the pitch size results in higher cardiovascular strain (Aroso et al., 2004; Tessitore et al., 2006), although Clemente et al. (2012) concluded that there is no consensus within the literature about the effects of pitch size on HR. Overall, increased pitch area increases HR, rate of perceived exertion (RPE) and blood lactate concentration. However, when looking at the effect of pitch dimensions on exercise intensity within SSGs, we need to differentiate between the absolute and relative pitch areas. The absolute area is the total pitch area (e.g., 40x20m), while the relative pitch area is the total pitch area divided by the total number of players (HillHaas et ai., 2011). This gives the individual playing area for a player (e.g., 10 square meters). Rampinini et al. (2007) found that a larger absolute pitch size resulted in higher exercise intensities (HR, RPE and blood lactate concentration) compared to medium- and small-sized pitches. On the other hand, Kelly and Drust (2009) stated that the pitch size does not influence the intensity of SSGs when the number of players involved is kept constant, but rather that it only altered the number of tackles and shots. It did not significantly change the number of other technical actions, such as passing, receiving, turning, dribbling, interception and heading. Casamichana and Castellano (2010) indicated that an increase in relative playing area results in a larger physical (i.e., total distance covered; distance covered in low-, medium- and high-intensity running; distance covered per minute; work-torest ratio; maximum speed; and sprint frequency) and physiological workload (i.e., percent of HR"'""' percent of mean HR, time spent above 90~& HR"'"). The effective playing time and RPE was also higher. Some motor behaviors (i.e., interception, contrai and dribble, control and shoot, clearance, and putting the ball in play) were shown less frequently, however. Some other studies have even found lower exercise intensities '\Nith an increased relative pitch area (Rampinini et al., 2007). 6.7.1.1 PitclJ size and tactica/ training Fradua et al. (2013) looked at pitch sizes extrapolated from full-size professional matches in relation to the training of tactical aspects. Individual playing areas of 65-110 square meters with a length-to-\vidth ratio of 1:1-1:1.3 are recon1mended \vhile training different tactical components. Coaches may use a relative pitch area of 90 square meters (\vithin a range of 70-110 square meters) for playing out fron1 the back and finishing, while 80 square meters (range 65-95 square meters) is recommended to recreate transition play in the middle of field. Also, longer widthto-length ratios are suggested for training transition play at this part of the field (length-to-width ratio of 1:1.3), anda square-shaped pitch (1:1) is recommended for playing out from the back and finishing sessions. FITNESS IN SOCCER FITNESS IN SOCCER High-íntensíty ínterva/ traíníng High-intensity interval training 6.7.2 6.7.2.1 Number of players involved Decreasing the number of p/ayers Generally, a lower number of players results in a higher exercise intensity, with increased HR, RPE and blood lactate concentration (Duarte et al., 2009; Owen et al., 2004; Sampaio et al., 2007; Williams and Owen, 2007). For example, a 3v3 results in higher HRs with more goal attempts, dribbling, passing, tackling, high-intensity activities, and total distance covered, combined with less jogging and walking, than during a 5v5 (Platt et al., 2001). An interesting observation was that players covered greater distances moving backward and sideways in a 4v4 compared to an 8v8 0-ones and Drust, 2007). Reductions in the number of players also increased the ball contacts per player (Balsom, 1999; Jones and Drust, 2007). This increased individual possession of the ball might be the reason for an increase in exercise intensity (Balsom, 1999; Reilly and Ball, 1984). Castellano et al. (2011), on the other hand, stated that reducing the number of players does not alter the physical load but rather just the physiological workload. A 3v3 provoked higher HR responses and RPE scores than a 4v4, 5v5 or 6v6 (Rampinini et al., 2007). Therefore, the smaller format was shown to be more intense. This was also concluded in some research studies concerning youth soccer. The physiological demands were found to be higher during 2v2 and 3v3 games when compared to a 4v4 game (Dellal et ai., 2011a). In another study, the HR and percentage of HRmnx were higher during 3v3 and 4v4 games in comparison to lvl and 2v2 games, although the 1vl game showed higher blood lactate concentration (Kõklü et al., 2011). It was therefore concluded that smaller game situations (e.g., 1vl) might support anaerobic adaptations for youth soccer players (Kõklü et al., 2013), but they also increase the technical demands. Players increased their number of touches from, on average, 13 ball contacts in a ten-minute 8v8 game to 36 ball contacts in a ten-minute 4v4 Uones and Drust, 2007). 6.7.2.2 lncreasíng the number of players Generally, a greater number of players reduces the exercise intensities during SSGs. Owen et al. (2004) found a lower mean HR and peak HR when players were added to a SSG. They also concluded that an increase in the number of players on the pitch leads to a decrease in technical actions per player. 6.7.2.3 Player number ín relatíon to pitch area An increase in absolute pitch area and player number may also result in a greater relative pitch area, as has been shown in severa! studies (e.g., Rampinini et al., 2007), and it seems that this lowers exercise intensity Uones and Drust, 2007). This observed reduction in the physiological parameters Uones and Drust, 2007; Katis and Kellis, 2009; Rampini et al., 2007) might have been the result of increasing the total number of players ora failure by the additional players to cover more ground within the absolute pitch area. When we decrease the number of players while keeping the relative pitch area constant, the physiological and perceptual workload increases as a result (Hill-Haas et al., 2009a). 6. 7.2.4 Havíng a floater or numbers up!numbers down Some studies have focused on the effects of having a fixed overload or underload situation, also known as having numbers up or numbers down, and the effect of having a floater (a player who is only allowed to play with the team in possession of the ball). Underloaded teams showed higher RPE scores compared to the numerically superior team but with no differences in blood lactate concentrations and %HRm~x· A 4v3 ora 6v5 showed no significant difference in physiological and perceptual responses compared to the games with a floater (3v3 +1 and SvS +1), but it seems that playing with a floater might be more beneficial for developing aerobic fitness. The floater covered more total distance, completed more sprints (>18km/h) and had a higher RPE score post-training when c;:ompared to the players on either the overloaded or underloaded team (Hill-Haas et al., 2010). Coaches sometimes put players returning from injury into the position of floater because they may have less risk of a contact injury due to the fact they cannot defend. However, coaches need to be aware of the abovementioned facts before they puta player in a floater position. That said, if you want to increase a rehabilitating player's aerobic fitness, you might want to consider him or heras a floater in a SSG. 6.7.3 6.7.3.1 Rule modifications The use of goa/keepers Generally, the use of goalkeepers may decrease exercise intensity, both in terms of physiological and physical load. The HR of the players will drop (Sassi et al., 2004; Mallo and Navarro, 2008) because players will protect their goal more carefully, and this reduces the tempo of the game. Dellal et al. (2008) did find an increase in HR while using goalkeepers in an SSG, and this might be due to an increase in players' motivation to attack and defend. The total distance and the time spent in high-intensity running will also decrease, and the time spent standing and walking will increase correspondingly (Mallo and Navarro, 2008). Players will have a higher HR and cover more distance when playing without a goalkeeper, and they will also have more ball contacts and make more short passes (Mallo and Navarro, 2008). Kõklü et ai. (2013) not only found an increase in HR but also in RPE, blood lactate concentration, total distance covered, and greater distances at speeds of 7.0-12.9 km/h, 13.0-17.9 km/h and greater than 18 km/h. So, if coaches want to place higher physiological strains on players, they should choose SSGs without goalkeepers if they want to reduce the physiological strain, or vice versa. If we look at the use of goalkeepers and the pitch dimensions in relation to tactical training, we can divide the pitch into six different areas: areas 1 and 2 for playing out from the back, 3 and 4 for midfield play, and 5 and 6 for finishing. Therefore, we can use the guidelines set up by Fradua et al. (2013). The distance noted is the distance between the goalkeeper and his closest teammate, according to the location of the ball, regardless ofbeing in or out of possession of the ball. The following distances are suggested: 5-lSm for zone 1, 10-20m for zone 2, 15--25m for zone 3, 20-30m for zone 4, and 25-35m for zones 5 and 6. FITNESS IN SOCCER High-intensity interval training FITNESS IN SOCCER High-intensity interval training 6.7.3.2 Ball possession Possession play generally affects the players' physical and physiological responses, meaning that the game demands are higher (Castellano et al., 2013). When the number of players was altered in a possession-based SSG, the HR response did not shov.r a significant change, but the physical demands decreased ivith a decrease in player numbers. An alteration in the type of possession game can also influence the technical and physical demands of SSGs. Forcing the players to play one-touch leads to less successful passes and duels. Therefore, more balls were lost during the game. It also lea<ls to higher blood lactate concentrations, RPE, and total distance covered in high-intensity rnns and sprints (Dellal et al., 2011b; Dellal et ai., 2012a). Even a permitted maximum of two touches leads to a higher perceptual training response in terms of a higher RPE score (Sampaio et al., 2007) and high-intensity running (Dellal et al., 2012a). Free play, on the other hand, led to lower RPE scores but only for defensive midfielders, wide midfielders and forwards (Dellal et al., 2012a). A coach can therefore manipulate the technical, physical and physiological demands by altering the amount of touches allowed. 6.7.4 Coach encouragement Even though we want our players to be internally motivateci, active anci consistent, coach encouragement provokes a sígnificant increase in players' physiological responses ciuring SSGs (Balsom, 1999). Higher HR, blooci lactate concentration, anci RPE scores were noted for SSGs with coach encouragement when compareci to SSGs without. It even had a greater impact on these factors than an alteration in pitch size anci playing numbers (Rampinini et al., 2004). 6.7.5 6. 7.5.1 Training regimen Continuous vs. intermittent An SSG can be conciucteci in either a continuous ar an intermittent manner. Casamichana et al. (2013) stated that a continuous format leads to higher physical load. However, others (Hill-Haas et al., 2009b) have founci that the intermittent format increased distances covereci faster than 13 km/h. These latter researchers also found higher percentages of HRmax anci RPE scores. Both regimens can be useci for aerobic maintenance training during the in-season (Hill-Haas et al., 2009b). Therefore, coaches can alter the physical anci physiological loads by choosing either a continuous or an intermittent SSG. 6.7.5.2 Work~to#rest ratio A factor that also influences the players' physical anci physiological loads is the tvork-to-rest ratio. Unfortunately, there is a lack of research looking at the effect of different ratios within SSGs, so \ve cannot make a clear recommendation of tvhich ratios might be better for alternating the load, but coaches need to keep in minci that this is also a crucial factor tvhen using SSGs in fitness training. 6.7.5.3 6.7.3.3 Goa/ orientation It seems that changing the 1ules of the game influences the technical, physical and physiological load, but also altering the task and goal orientation can influence the acute physiological response. Duarte et al. (2010) showed that players' HRs were less variable during an SSG with goals scored by dribbling over a line when compareci to both double and central goal orientations. Therefore, if you want an SSG with less variation in HR, it might be better to choose an SSG tvith a line goal constraint. 6.7.3.4 Tactical obligations Besides giving the players technical constraints to <leal with during SSGs, we can also alter the tactical objectives during the game. Obligíng players to put pressure on the team in possession results in a higher mean HR (Sassi et al., 2004). Playerto-player marking increases blood lactate concentration (Sassi et ai., 2004) and RPE scores (Sampaio et al., 2007). Therefore, coaches can also alter the physiological load by giving the players tactical assignments during SSGs. SSG duration The duration of an SSG can also influence the exercise intensity, but it does not affect the technical actions per minute. When we increase the duration of a 3v3 from 2 minutes to 4 and 6 minutes, there is a significant effect of duration on HR. The HR response was lower in the first setting when compareci to the other two, but the intensity dropped when moving from the 4-min to the 6-min SSG. The RPE score increased linearly with duration. Even though the differences were small in this study (Fanchini et al., 2011), coaches may change the duration of an SSG to influence the physiological load. 6. 7.5.4 Number of sets and repetitions The number of sets and repetitions can also alter the technical, physical and physiological performance. Generally, the amount of high- anci very-high-intensity activity decreases, while blood lactate concentration, RPE and HR response increase from the first repetition of an SSG to the fourth and last repetition. The amount of ciuels and percentage of successful passes is also higher at the beginning of the first two repetitions when compareci to the last. Therefore, more balls were lost during the four reps (Dellal et al., 2012b). Hence, the number of sets and repetitions also seems to be an important variable in determining the training stimulus when fitness training with SSGs. FITNESS IN SOCCER High-intensity interval training 6.7.6 6.7.6.1 Players' characteristics Fitness levei Stone and Kilding (2009) reviewed the literature carefully and concluded that players with the highest V02max had the lowest percentage of V02 nrnx during SSGs. It follows that maybe the players with high vo2max values should play as floaters in arder to get a higher aerobic workload during SSGs (Hill-Haas et al., 2010). Indeed, a ceiling effect on improving aerobic fitness when solely using SSGs for fitness training may be evident for players who have a very high leve} of aerobic fitness (McMillan, unpublished observations). These players may have to include generic running sessions into their weekly training regime (i.e,. 4x4 min runs at 90-95% of HRmax' McMillan, 2005) in order to further improve their aerobic fitness, 6.7.6.2 Skill /eve/ A lower skill level usually results in a lower technical performance during SSGs, but with higher physical and physiological loads. Amateurs had a lower percentage of successful passes, and even though they had a greater amount of ball possession, they lost more balls per possession time. ln contrast, they >vere involved in fewer duels per minute (Dellal et al., 2011c), but this may be explained by the fact that professional soccer players have better anticipation skills (Reilly et al., 2000) and a faster running speed (Kaplan, Erkmen and Taskin, 2009). The type of bali possession and goal orientation in SSGs had a strong influence on the HR response of amateur soccer players. For example, an SSG with free play and an objective to keep possession of the ball showed a higher HR compareci to an SSG with a floater or the presence of a neutral zone (Dellal et ai., 2011c). Non-professionals also covered less distance overall, especially during high-intensity running and sprinting in one-touch soccer and free play. Reducing the amount of touches allowed (one or tvvo touches) led to a greater difference betvveen amateurs and professionals in terms of physical load. Amateurs also showed higher RPE and blood lacta te concentrations, \Vhereas the HR responses, expressed in percentages of HRm"" were similar to professionals (Dellal et ai., 201lc). Therefore, D~l­ lal et al. (2011c) recommend that amateur coaches use at least tvvo touches, while professional soccer coaches should use only one or two touches per ball possession to recreate an elite game situation within SSGs. Coaches should also ensure that fitness and skill mismatches are not present betvveen the teams participating in SSGs. 6.7.6.3 Age Dellal et al. (2011a) stated that youth players do not have the sarne technical abilities and experience as adults, and this could lead to greater physical demands for youth soccer players within SSGs. However, youth players with lesser skill may not be able to achieve and maintain the required physiological stress because they are unable to consistently maintain the speed of the technical executions. This may lead to counterproductive training sessions (Castagna et al., 2005). Therefore, the age of the players has to be taken into account when developing SSGs. FITNESS IN SOCCER 1 High-intensity interva/ training 97 6.8 TRAINING TIME DISTRIBUTION When examining the effect of training intensity distribution on aerobic fitness variables in elite soccer players, Castagna et al. (2011) reported that even though almost two-thirds of players' training time was spent at low intensities, only the time spent at high intensity (90% of HRma..) was related to changes in aerobic fitness. Impellizzeri et al. (2005) reported similar findings and demonstrated a significant correlation between time spent in high-intensity zones and changes in oxygen uptake at lactate threshold These results highlight the effectiveness of high-intensity training in soccer. It is believed that an optimal stimulus to elicit both maximal cardiovascular and peripheral adaptations is one where athletes spend at least several minutes Per session in their "red zone," which generally means reaching at least 90% VO2m~>: (Buchheit and Laursen, 2013b). High-intensity training that raises the HR to above 90% of HRmax should constitute at least 7-8% of the total weekly training plan for elite soccer players during preseason and in-season (Castagna et ai., 2013). FITNESS IN SOCCER FITNESS IN SOCCER High-intensity interval training High-intensity interval training 6.9 SOCCER-SPECIFIC TRAINING DRILLS The drills presented below are examples of soccer-specific drills than can be perforrned as high-intensity interval training to elicit anaerobic and aerobic adaptations. 6.9.1 vo2m~x interval Explanation Position play 7v6 in the box. When the ball is intercepted, the defending team plays the ball to the other side, where their teammate asks for the ball and continues to play 7v6. ln the middle of the field, \Ve put three openings, marked by cones. This is dane to oblige the waiting player to move during the game and ask for the ball through one of these openings. Variation If the team in possession of the ball can make ten consecutive passes, they can finish on the goal and keep possession of the ball \vhen they score. One player of this team can infiltrate the 16 meter and score in a lvl situation \vith the GK. Afterwards the coach puts a ball back into play. Comments When the bali is out of play, the coach puts a new one into play. The defending team has to intercept the ball and then play to the other side in arder to become the attacking team. Explanation This game is played 6v6 in the center zone. When three successive passes have been made, a player in the end zone can be played to. This player may then finish with a maximum of two touches. Variations • Number of touches: • Unlimited • Two or three touches • Two teams of eight players on the entire pitch, \Vith the hvo end zones in the large rectangle. • One-touch finishing. Comment • The game is played with offside. • The reference point is the line of the end zone. Explanation A possession game \Vith three teams of four players. T\VO teams of four players try to keep possession, while the third team of four players tries to win the bali. The team that Iases the ball becomes the defending team. This \Vay, the game is played 8 against 4. i: Variations • When the defending team recovers the bali, they need to dribble outside 1-------i--~-+-----­ of the field to emphasize the infiltration into the available space. The two possession teams need to prevent this (transition). If the hvo possession teams prevent them from dribbling • Number of touches on the ball: • Unlimited outside the field, they keep posses• T\vo touches sion of the ball. • Mandatory one touch after playing hvo o After the defending team recovers touches the bali, they need to dribble outside the area and score in one of the small o Ball may not be played to a teammate goals. The two other teams need to o The ball may not be passed back to the player you received the ball from. prevent this. Explanation This game is played 6v6 in the center of the pitch. A player can enter the end zone after three successive passes and finish on the big goal or score in one of the two small goals, which are placed in the beginning of the end zone. The player who has to finish on goal has a maximum of two touches. By adding the small goals to the game, we create more decision-making moments for the players and emphasize the transition movements of the players. Variations 0 When a player enters the end zone and receives a pass, one opposing player can enter the end zone to defend. 0 When a player enters the end zone and receives a pass, one of his teammates can enter the end zone as well, together with one opponent, and finish in a 2vl situation plus the GK. 0 Number of touches: • Unlimited 0 T\VO or three touches • T\VO teams of eightplayers on the entire pitch with the hvoend zones in the box. • One-touch finish • Numbers of passes before playing to the end zone • {j Comment • The game is played using the offside rule. • The reference point is the line of the end zone. lOO 1 FITNESS IN SOCCER High-intensity interval training j 101 FITNESS IN SOCCER High-intensity interval training 6.9.2 vo2max interval and repetition exercises Explanation Possession game with SvS. A point can be scored by playing to a teammate in one of the two end zones. Explanation 3+GK versus 3+GK+2. A transition exer- cise with hvo teams of six players each. Three players of each team \vait next to the goal, \vith one player keeping a ball at his feet in order to be ready to enter the pitch as quickly as possible. Each Variations o The team that scores a goal can gain an extra point by having a second player entering the end zone and receiving the ball from the first player that entered the end zone. The defending team is now allowed into the end zone to prevent the pass from the first to the second player and therefore avoid conceding another point. o The game can also be played with two goalkeepers in the end zones. o Free play, one or two touches. time the ball cresses the goal line (as \Vell as in the event of a goal), the team standing behind that goal line can immediately enter the pitch by dribbling the bali, which means that the attacking team has to change over to defense straightaway. Variations Number of players: 3 v 3 l Comment Coaches monitor offside rule on the offside tines (line between the hvo zones). Comments At least one pass must be made before a goal can be scored. Explanation . T\VO teams of five players. On one half of the field, they play 5v3, 'vhile the remaining hvo players wait on the other half. When the three players recover the ball, they can score on the big goal. After they make an attempt on the goal, the coach plays a new ball towards the hvo waiting players, and the minority team becomes the majority team and vice versa. You \vill create many defensive and offensive transitions with this organization. Variations o Number of touches o Different numbers of players Comments ° Coach plays a ne\v ball into the vacant rectangle \vhenever the ball goes out. ° Coaches keep track of hoiv often the attacking team loses the bali. 0 Game can be played position specific, creating many defensive/ attacking transitions. {t 1( • 11 11 t t *) Explanation Ball possession exercise using two teams of eight players. On one half of the pitch, ,.,,e play an 8v4 possession game, \Vhile four players of the defending team wait on the other half of the pitch. When the majority team can make five consecutive passes, they transition to the other half of the pitch, \Vhere they also play 8v4 and try to score a goal as quickly as possible. After a goal attempt by the attacking team, the coach plays a bali to the four 'vaiting players (defensive team), and they play the sarne game. If the defending team can recover the ball before the goal attempt, they change sides and play 8v4 as the majority team. Variations ° Can be played \Vith different numbers • Can be played without GK and with small goals Comment Coaching to\vard moments. quick transition FACULDADF OE DESPORTO DA UNIVERSIDADE DO PORTO 102 j FITNESS IN SOCCER FITNESS IN SOCCER Hígh~intensity 6.9.3 High-intensity interval training ínterval trainíng Long interval and repetition exercises Explanation 3v3 in the playing area. Three suppor- ting players from each team stand on three sides of the rectangle. The three supporting players can occupy the four sides of the pitch, encouraging them to see and use the free space and make space for each other. The players inside the field play a possession game, using the three supporting players, and try to make ten consecutive passes in arder to score a point. The players inside cannot use the sarne supporting player twice in a row, obliging them to change directions. The supporting players cannot defend each other. ~ n t ~ "f{ li Variations • Number of touches on the bali • Points can be scored in other \Vays, for example by: • Passing to a third player • 1-2 after passing to the second player, etc. • It's possible to add small goals, anda team may score after a certain number of consecutive passes. li Comment Players off the pitch cannot pass directly to each other. Variations o Number of touches º Can also be played with three teams of eight players each Comments • Coaches play a ne\V ball into the vacant rectangle whenever the bali goes out. o Coaches keep track of how often the attacking teams lose the ball. Explanation ln this exercise, hvo teams (right side v left side) play against each other. The players are set up according to the positions they play in matches. The players then try to score as much as possible on the left and right. A point is scored when scoring directly from a cross. The trainer / coach can then install the tactical guidelines according to his own running lines and movements by introducing ne\v passing directions each time. Variation The game can be played with ar \vithout defenders. Comments • Ensure that all positions are covered. The players resume their positions as fast as possible immediately after the action. • Emphasize the competitive element. Explanation Three teams of six players each. T\VO tean1s of six players (attacking) take up their places in the outer boxes. The defending team puts three players in the middle section and three players play 6v3 in one of the two rectangles. The hvo attacking teams play the bali around, and they can also play the bali to the other rectangle. The players in the middle section of the defending team then try to win the bali in that rectangle, while the other three players move to the middle section. They try to intercept the ball from being played to the other rectangle. The game is played for nvo minutes. The defending team tries to intercept the ball as often as possible. The teams are then changed. Progression The players are allo\ved to S\Vitch to the wing position. The fullback then becomes the \Vinger. The backs and midfielders can also change so as to give everyone the chance to finish. Medium interval and repetition exerdses J -~-------------"-----­ 103 FITNESS IN SOCCER flTNESS IN SOCCER 1041 High-intensity interval training 6.9.4 High-intensity intervaf training Short interval and repetition exercises Explanation The game is started by one of the coaches \vho centers to the GK, \vho then launches the counter-attack. The game is played 4v2 or 4v3, depending on the progression. The players are given a limited amount of time to score. Comments Defenders can score in the other goal \vhen they recover the ball. Progression Groups of four attackers and hvo or three defenders. Explanation Severa! boxes are set out, each containing two players. Two neutral players move from box to box soas to play 3vl. The player in the box can play the ball to a teammate in another box. The player in the box keeps the ball until he gets support from the other players. Variation Play lvl in each rectangle, with hvo neutral players providing support in the boxes to create a 2vl situation. - - ~--- , __ ___ _ SUMMARY High-Intensity Interval Training is a time efficient and very effective way of improving a football player's anaerobic and aerobic fitness levels. Training drills with or without the bali can be both used, but as much training should be performed with the ball as possible. Therefore, SSGs are an excellent choice of drill to improve a player's physical abilities. The coach has to remember that factors such as pitch size, number of players, rules, and coach encouragement can all affect the intensity of SSG play. Soccer players with very high leveis of fitness may benefit from the addition of individualized generic running drills to their training program. Performing 4 x 4 min intervals at 90-95% of HRrnax using the J-Ioff track is a useful drill to use in addition to SSG play. Although perhaps less motivating for players to perfonn, it is easier to control the intensity of generic running drills, making it easier to individualize training. Using a combination of SSG play and generic running drills during a high-intensity interval training session is suggested as an optimal way of improving the anaerobic and aerobic fitness of soccer players. It seems important that high-intensity interval training that raises the HR to above 90% of HRmox should constitute at least 8 to 10% of the total weekly training plan for elite soccer players during the preseason and in-season periods. REFERENCES ,\cton·/açobc,, R., Fluck, D., Bom1'', T.C., Burgi, S., Chriotcnson, P.M., Toii;;o, M. and Lundb}~ C, 2013. !mpro"cmcnts in cxcrci~c performance with high·inlenoily intcrvnl trainini;; coincide woth an incn:a~c ln ~.kdc!nl mw;clc milochondrinl rontent and funclion. Joumnl of Apphcd Physiology. 1\guinr, M., Botelho, G., l:igo, C., Maça.<;, V. and S.imp;iio, )., 2012. 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J Strength Cond Res, 25(5), pp.1279-8·1 0 i 107 1os I FITNESS IN SOCCER interval tralning FITNESS IN SOCCER 1 Speed, agility and quickness (SAQ) and repeated sprint ability (RSA) High~intensity SPEED, AGILITY AND QUICKNESS (SAQ) AND REPEATED SPRINT ABILITY (RSA) Jan Van Winckel, Nick Winkelman, Rena/do Landburg, Paul Brad/ey 7.1 INTRODUCTION Although most of a game is played at low intensity, rnany high-intensity actions are also involved, such as sprinting, jumping, tuming and tackling. Around 2~'b of the total distance covered during a match is sprinting, \Vhile another 10% of the total distance covered is from high-intensity running. This equates to a 10-!Sm sprint every 90 seconds (Bangsbo, 2006). Most of these sprints are short bouts of exertion (< 15m). Straight-line sprinting is the most frequently occurring action prior to a goal, for both the scoring and assisting players. Professional players have become faster over time, indicating that sprinting ability is becoming more and more important in modern soccer (Haugen et al., 2013). ln a recent study, Andrzejevvski et ai. (2013) conducted a detailed analysis of the sprinting activity of professional soccer players during the 2008-09 and 2010-11 UEFA Europa League seasons. The study demonstrated that the mean total sprint distance covered by players (>=24 km/h) amounted to 237m ± 123m. ln terms of the position of play, forwards covered the longest sprint distance (345m ± 129m), which was 9~1a further than midfielders (313m ± 119m) and more than twice that of central midfielders (167m ± 87m). The average number of sprints performed by the soccer players was 11±5. Another notable fact was that 90% of sprints performed by professional soccer players \Vere shorter than five seconds, while only 10% lasted longer than five seconds. 109 FITNESS IN SOCCER llO 1 Speed, agility and quickness (SAQ) and repeated sprint ability (RSA) 7.2 NATURE OR NURTURE Speed is partly innate. Each individual has a unique blueprint by which their neuromuscular system is expressed within the human body. These individual differences can allow one individual to run faster, while another may be more inclined to run farther. Although it seerns that speed is partly innate, deliberate practice plays an important role in the development of talent. Balyi (2004) described a potential window of trainability that seems to exist. Young athletes should train speed at critica! moments in order to maximize genetic potential. Strength and power programs have been shown to improve speed, with superior running mechanics affecting the development of speed significantly. Sander et al. (2013) investigated the influence of a two-year strength training program on power performance in elite youth soccer players. The players who completed the strength training program displayed significantly better improvements in sprinting (up to 6%) when compared to the control group. The researchers suggest that it seems beneficial for youth players to perform strength training to exploit the reserve capacity in sprint performances. Similar to this, Comfort et al. (2013) examined the association between strength and sprint performance. The researchers concluded that leg strength is closely related to both sprint and jump performance in well-trained players. Finally, they stressed the importance of using squat exercises as part of a periodized training program. 7.3 FITNESS IN SOCCER 1 Speed, agilíty and quíckness {SAQ) and repeated sprint abi/ity (RSA) energetic cost. When running without arm swings, the net metabolic power demand increases by 8% when compared to running with arm swings. Once a runner is up to speed, the arms swing largely like passive pendulums. Pontzer et al. (2009) supports a passive arm swing hypothesis for upper-body movement. During human walking and running-in which the trunk and shoulders act primarily as elastic linkages between the pelvis, shoulder girdle and arms-the arms act as passive mass dampers, reducing torso and head rotation, and the upper-body movement is primarily powered by the lower-body movement. Although arm movements do not control leg movements and have very little effect on the all-important ground reaction forces, the arms and legs need each other to achieve proper running form. 7.3.3 Muscle actions Running gait can be divided into two phases with regard to the lower extremity: the stance phase and s1ving phase (Nicola et al., 2012). These can be further divided into absorption (foot strike), propulsion, initial s1ving and terminal swing. BIOMECHANICS OF SPRINTING Fig. 7.1: Absorption (foot strike), propulsion, initia/ swing and terminal swing. 7.3.1 Stride length and stride frequency Speed is simply the product of the frequency (Freq) and length (L) of a runner's steps. Speed = L step · Freq step Sprinters achieve faster top speeds not by swinging their limbs more rapidly in the air, but by applying greater forces to the ground. How fast an athlete runs is determined during contact with the ground. Both the greater stride Iengths and frequencies of faster runners result from the application of greater mass-specific ground forces in shorter periods of time. Lockie et ai. (2013) investigated stance kinetics and step kinematics. Their results indicated that faster acceleration in field sport athletes involved longer steps with shorter contact time. Greater vertical force production was linked with shorter contact time, illustrating efficient force production. Greater step lengths during acceleration were facilitated by higher vertical impulses and appropriate horizontal force. The researchers concluded that speed training for team sport players should be customized to encourage these technique adaptations. 7.3.2 Arm swinging Humans walk with a moderate step width (+/-12 cm), which guarantees balance and minimizes energetic cost (Donelan et al., 2001). Conversely, humans run with a step width of almost zero. This jeopardizes balance and requires a greater energetic cost. While running, arm swings support the lateral balance and reduce the Swing phase. At the end of the stance phase, when the foot has straightened out and left the ground, the hip, knee and foot are stretched. The glutei and the hamstrings are used to stretch the hip, while the calf muscles cause the foot to stretch. The iliopsoas muscle (the muscle that bends the hip) then comes into action to move the lead leg forward. The hamstrings ensure the bending (flexion) of the knee, and the tibialis anterior (the muscle above the shinbone) causes the foot to bend (dorsal flexion). The adductors work to prevent the thigh from turning outwards. Finally, the knee extends through the action of the quadriceps to prepare the body for landing. Stance phase. When running, the large muscle groups work eccentrically to prevent the runner from sagging at any of his joints by counteracting flexion of the ankle, flexion of the knee and flexion of the hip. When landing, the glutei pull in order to stretch the hip. The antagonists of the thigh, the hamstrings and quadriceps, work mainly to stabilize the knee and control the movement. The antagonists also work together in the lower leg to allo1v the foot to straighten in a controlled manner. The tibialis anterior at the front of the tibia works eccentrically, while the calf muscle (gastrocnemius) works concentrically. No more muscle activity can be undertaken to push the body forward in this support phase because the center of gravity is behind the point of support. It is the movement of the body that ensures itis carried over this point of support. 111 FITNESS IN SOCCER Speed, agílity and quickness (SAQ) and repeated sprint abi/ity (RSA} 7.4 RUNNING TECHNIQUE The running motion we are familiar with from the world of athletics cannot be fully applied to soccer. The shortest sprint distance in athletics, the lOOm, is more than three times longer than the longest typical sprint covered by a player during a match. The expression of speed is relative to the absolute distance and the phases leading to the final distance. Fast people, whether on a field or on a track, will adopt similar running forms based on the distance. Soccer involves cutting, htrning, changing direction, falling, jumping, stoppíng, accelerating and various other basic forros of movement. A player must always have as much contactas possible with the ground in arder to be able to anticipate changing situations. The following are specific to soccer: 0 The distance is very short, which means that the support point is mainly behind the body. The quadriceps and calf muscles, as well as the glutei and the lower-back muscles, therefore push on this support point. This movement is similar to track athletes over the first 15m. 0 A soccer player should be able to change direction quickly. A high heel or knee lift will make the swing phase too long and therefore compromise a swift change of direction. 0 Soccer players do not run around bends, like on a track, but rather turn at sharp angles. 0 Sprint distances in soccer are very short, meaning that stride length needs to be restricted. For this reason, stride frequency is more important and must therefore increase greatly over the first few meters. However, coaches should be cautious when trying to artificially influence stride frequency, because it could threaten an athlete's natural running flow. • Cross-coordination (opposite arm/leg) is not always possible in practical terms because of different arm movements, such as holding off an opponent. • The start of the movement does not only go in a forward direction but rather from all angles and positions, such as crossovers, side stepping, landing from a jump, accelerating away, and so on. Soccer players therefore have to train especially on short, fast running actions, and these can be combined with a good stretch reflex anda high stride frequency. 7.5 SPEED, AGILITY, QUICKNESS ANO CUTTING Straight-sprint training appears to have little or no influence on the improvement of sprinting that involves changes of direction (Young et al., 2001), and this was confirmed by Tsitskarsis et al. (2003). These researchers found a weak relationship between straight-sprint performance and speed performance when changes of direction are involved. ln an interesting investigation by Little and Williams (2005), the specificity of acceleration, maximum speed, and agility in professional soccer players was examined. Although the performances in the three tests \Vere all significantly correlated, the coefficients of determination (R2l between the tests were just 39, 12, and 21% for acceleration and maximum speed, acceleration and agility, and maximum speed and agility, respectively. The investigators concluded that acceleration, maximum speed, and agility are specific qualities and relatively unrelated to one another. They therefore suggested the use of specific testing and training procedures for each speed component when working with elite players. FITNESS IN SOCCER Speed, agility and quickness {SAQ} and repeated sprint abi/ity (RSA) 7.6 DEFINITIONS Agility and change of direction (COD): An agility task may be best described as a rapid, whole-body change of direction or speed in response to a stimulus (Sheppard and Young, 2006). Other attempts to define agility have focused on the physical demands only, generally a change of direction involving the whole body, as vvell as rapid movement and direction change of limbs (Tsitskarsis et al., 2003). The unique distinction between the definition used by Sheppard and Young (2006) and other previous definitions is the inclusion of reaction to a stimulus, rather than just change-of-direction speed (COD). Agility is an open skill, while COD is a closed skill (Sheppard and Young, 2011). Quickness: Moreno (1995) identified quickness as "a multi-planar or multi-directional skill that combines acceleration, explosiveness, and reactiveness." Quickness can be defined by the speed of agility or COD over short distances. Cutting: Unlike the term quickness, cutting seemingly refers only to the specific portion of a directional change when the athlete's foot touches the ground to initi~ ate the change of direction (Sheppard and Young, 2006). 7.7 SOCCER-SPECIFIC SAQ DRILLS SAQ is the harmonious and economical cooperation of the senses, nerves and muscles to produce a specific, controlled movement and a rapid situation-specific reflex. This requires the entire locomotor apparatus to work together in a coordinated way in the following areas: o speed of execution o angle of n1ovement 0 direction of movement 0 activation and deactivation of synergists and antagonists • muscle tension 0 number of motor units recruited Speed, agility and quickness are criticai for success in soccer. SAQ-specific exercises in soccer therefore have to be directed to\vard the following objectives: 0 Making SAQ exercises dependent on visual stimuli: Instead of training with a whistle, drop a ball, for example, when the players are supposed to take off. 0 Break up rhythms: A sprint in soccer is characterized by accelerations and changes in direction. ° Fast foot contacts and soccer-specific activities. • Link a coordination exercise with an activity specific to soccer, such as by organizing a passing or finishing exercise after a sprinting activity. 1 113 114 1 FITNESS IN SOCCER FITNESS IN SOCCER Speed, agility and quickness (SAQ) and repeated sprint ability {RSA) Speed, agility and quickness {SAQ) and repeated sprint ability (RSA) 7.7.1 Effectiveness of SAQ sessions Young and Rogers (2013) examined the effect of two different training methods on planned and reactive agility tests. Twenty-five young adult Australian Rules football players (UlS) were randomly assigned to two training groups: 1. The change of direction group 2. The sn1all-sided game group Players participated in one or two 15-minute sessions per week, with 11 sessions being conducted over a 7-week period during the season. A planned AFL agility test and a video-based reactive agility test were performed before and after intervention. The small-síded games group improved total time in the reactive agility test (P = 0.008, effect size = 0.93) and this was entirely dueto a very large reduction in decision time. Meanwhile, the change-of-direction training produced small to trivial changes in all of the test variables. ln another study by Jovanovic et al. (2011), the effects of SAQ training methods on power performance in soccer players were investigated. The SAQ training program appears to be an effective way of improving some areas of power performance in young soccer players during the in-season period. Soccer coaches could use this information in the process of planning in-season training. Without proper planning of SAQ training, soccer players will most likely be confronted with decreased power performance. Finally, Bloomfield et ai. (2003) compared the effectiveness of two methodologies for speed and agility conditioning for random-, intermittent-, and dynamic-activity sports like soccer and investigated the necessity of specialized coaching equipment. Two groups participated in either a programmed method (PC) or a random method (RC) of conditioning, with a third group receiving no conditioning (NC). The PC participants used the SAQ conditioning method, while the RC participants played supervised small-sided soccer games. The PC group was also subdivided into hvo subgroups, where participants either fc;:;~;?TiTE'i~Ti'::;:!i:c''T:::CX'!::Z"iJi;'iÇ\'.'.~iF''.''.'. used specialized SAQ equipment or no equipment. PC in the form of SAQ exercises \vas found to be a superior method for improving speed and agility parameters, and this study found that specialized SAQ equipment was not a requirement to observe significant improvements. In addition, the authors recommended the presence of a fitness specialist in speed and agility conditioning to lead, direct, and control PC, particularly the specificity and overload. This appears to be more beneficial than the laissez-faire approach of RC when trying to improve aspects like speed, power, and agility. 7.8 SPEED Speed comprises a number of different components: 1. Reaction/ starting speed: The first three or four strides 2. Acceleration: 10-20m 3. Speed endurance: 60-70m 4. Repeated sprint ability: Repeated sprints sometimes with little recovery time in between. 7.8.1 Reaction speed Seen in neuro-physiological terms, reaction speed is the time interval during which the nerve impulses are conducted to the brain, where they are processed and then sent to the respective muscles. The reaction speed is determined by various factors, including age and gender. Although it has already been proven in the past that sprinters react more quickly than long-distance runners, no differences were found in the reaction time between different skill groups. Professional soccer players do not have a quicker reaction speed than amateur players. The best-known example of this is the boxer Mohammed Ali, who had a very slow visual reaction time (190msec), yet heis one of the best boxers of all time because of his ability to anticipate more quickly than others. 7.8.2 Starting speed The energy for this type of exertion is supplied by the ATP still present in the muscles. ATP is always found in the cell, although it can fall to 40%, while CP (creatine phosphate) can be exhausted. • Duration: One or two seconds • Intensity: 100% • Repetition: 8-10 • Work-rest ratio: 1:10 7.8.3 • " " • Acceleration Dufation: 2-6 seconds Intensity: Building up to 100% Repetition: 4-6 Work-rest ratio: 1:10 Varley et al. (2013) compared the match activity profiles of elite players from Australian Rules football (AF), rugby league (RL) and soccer (SOC) using identical movement definitions. Rugby league players undertook the highest relative number of accelerations (1.10 ± 056 per min). Repeated sprint bouts were rare for all codes. RL and SOC players performed less running than AF players, possibly due to limited open space because of field size and code-specific rules. 7.8.4 " " " • Speed endurance Duration: 6-10 seconds Intensity: Building up to 100% Repetition: 4-6 Work-rest ratio: 1:6 1 115 llG I FITNESS IN SOCCER FITNESS IN SOCCER Speed, agility and quickness (SAQ) and repeated sprint ability (RSA) 7.8.5 Repeated sprint ability (RSA) We have already discussed how the ability to repeatedly perform short-duration, high-intensity, intermittent exercise bouts with relatively short recovery times (e.g., repeated sprint ability or RSA) is an important attribute of the modern-day soccer player. The mean time recorded during an RSA test predícts the amount of high-intensity running and the total sprint distance covered during a professional soccer match (Rampinini et al., 2007), and this finding suggests that improving RSA should result in greater physical performance in team sports (Bishop et al., 2011}. It has been suggested that the ability to resynthesize phosphocreatine (PCr) may be an important determinant of the ability to reproduce sprint performance (Bishop et al., 2011). A short recovery time between repeated sprints leads to only a partia! restoration of PCr stores (Bogdanis et al., 1996). Importantly, Haseler et ai. (1999) demonstrated that PCr restoration is limited by 0 2 availability. This suggests that individuals with an elevated aerobic fitness should be able to more rapidly resynthesize PCr between repeated sprints (Bishop and Spencer, 2010; Rampinini et al., 2010; Bishop et ai., 2011). Indeed, high-intensity inlerval training (HIIT: 6-12 reps [2 minutes at ~ 100% vo2max= 1 minute rest]), can significantly improve the resynthesis of phosphocreatine during the first 60 seconds after high-intensity exercise (Bishop et ai., 2008). Sloth et al. (2013) reviewed the effects of sprint interval (repeated sprint ability) training. All 19 studies in their review used consistent training methods. The training sessions included 3-7 30m maximal sprints with 2-5 minutes recovery. They found that high-intensity sprint interval training improves fitness or V02m•x (maximal oxygen consumption) by 4-13%. Compareci to traditional endurance training (Iong, slow distance runs-Steinhofer terminology), the improvements in aerobic fitness were almost equal. Moreover, a small improvement in running economy was found, meaning that players used less energy for the sarne load. Finally, sprint interval training also improved anaerobic fitness and resistance to shortterm fatigue, thus improving repeated sprint ability. Perroni et al. (2013) investigated the effect of eight weeks of preseason training on RSA in soccer players. An RSA test, consisting of 7 x 30m sprints with 25 seconds of active rest, was administered to the players, before and after the eight weeks of preseason soccer training. An overall significant difference was found behveen the seven sprints performed pre- and post-training. The study shows that each sprint time was significantly faster in the pre- than in the post-RSA tests. Dellal and Wong del (2013) compareci the performance in RSA and repeated COD among elite soccer players in different age categories. The researchers discovered that the RSA and repeated COD are dependent on age, so coaches should therefore plan a specific program dífferentiating RSA and repeated COD, while the individualized training could begin at U17. Bishop et al. (2011) gave two key recommendations based on the existing literature: 1. It is important to include some training to improve single-sprint performance. This should include (i) specific sprint training, (ii) strength/ power training, and (iii) occasional high-intensity (>VOim,,,J training (e.g., repeated, 30-second, allout efforts separated by,.., 10 minutes of recovery) to increase anaerobic capacity. Speed, agility and quickness {SAQ} and repeated sprint ability (RSA) 2. It is also important to include some interval training to better improve the ability to recover between sprints (if the goal is to improve fatigue resistance). High-intensity (80-90% of V0 2m,.J interval training, interspersed with rest periods (e.g., one minute) that are shorter than the work periods (e.g., two minutes) efficiently improves the ability to recover between sprints by increasing aerobic fitness (V0 2mnx and the lactate threshold), the rate of PCr resynthesis, and buffering capacity. o Duration: Varying from 1-6 seconds per sprint o Intensity: Building up to 100% o Repetitions: 5-10 sprints in one set o Work-rest ratio: 1:2 between different sets of sprint exercises 7.9 TIPS SAQ training can be completed at the beginning or end of the session or as part of a warm up. All aspects of speed (e.g., agility, change of direction, quickness, and cutting) should be at least maintained in every microcycle. o Take into account the mechanical load while training agility, quickness, and cutting. These kinds of training sessions have limited impact (in cases of adequate recovery) on the physiological load, but they can have a considerable mechanical load. 0 Try to integrate your sessions with the technical / tactical objectives of training, but ensure this doesn't compromise the quality of execution. 0 Respect work-rest ratios when developing speed. o Warm up properly before doing SAQ training. o Don't do static stretching before SAQ training (This is discussed in more detail in Chapter 19). o Power, RSA and resistance (plyometrics) training can be performed on the field, but this should be dane intelligently as part of a periodized plan and only then in the loading phase of the microcycle. o 1 117 FITNESS IN SOCCER Speed, agi/ity and quickness {SAQ) and repeated sprint abilíty (RSA) 7.10 EXERCISES Explanation Players do a passing / finishing exercise with starting. acceleration, or maximal speed incorporated. Xl plays to X2, who then plays back to Xl. Xl plays the ball deep, and X2 sprínts toward the cone and crosses the ball. X3, X4, XS and X6 sprint to\vard the box and finísh the cross. Make hvo groups \Vho \Vork x times left and x times right and make a competition out of this play. Xl goes to )(2, and X2 goes to Xl (they stay at the sarne hvo positions at both sides of the exercise). X3, X4, XS and X6 can go one position to the right each time. Explanation T'vo teams are formed next to the goal. Xl plays the ball to X2 and immediately sprints around the flag. X2 takes the bali and tries to score from outside the penalty box \Vith a maximum of two touches. XI then receives the ball from the following player. Variation Xl plays the ball to X2. X2 passes to Xl. Xl plays to X3. X2 then receives the ball from X4. (See figure) Comment The coach plays a new ball in if the ball goes out. Explanation Player XI crosses to X4, who then sprints to the position for goal. X4 finishes and immediately sprints out of the 16-meter box. He then takes the place of Xl, \vho then runs behind the goal to position X2. Comment Emphasis on the sprint action and immediate sprint after finishing. Advancing X4-Xl-X2-X3-X4 FITNESS IN SOCCER Speed, agility and quickness (SAQ) and repeated sprint abi/ity {RSA) Advancing The players stay on the sarne side each time, with each player kicking six times before being changed. Variation o Coach can emphasize different running lines to\vard the goal. • Adapt distances and maybe the \Vorkrest ratio for different kinds of speed trainíng. Explanation Both players set off \Vhen the signal is given by the coach (by dropping the ball from his hands, a visual signal). The players run the course discussed beforehand. The first player to run behveen the flags gets a point. Variation The course can be altered using the sarne cones. Comment Let the players count the points themselves and give the laser an additional task. In the event of a tie, they both Jose. Advancing The players change places each time. Comment Assistant coach keeps track of the scored goals. Advancing You can do the exercise position specific. 1 119 120 1 FITNESS IN SOCCER Speed, agi/ity and quickness {SAQ) and repeated sprint ability (RSA) FITNESS IN SOCCER Speed, agilíty and quickness {SAQ) and repeated sprint ability {RSA} Explanation Both players set off \vhen the signal is given by the coach (by dropping the bali from his hands, a visual signal). The players run the course discussed beforehand. On reaching the ball, they try to score in the small goals. Scoring gets them one point. The first player to run behveen the flags also gets a point. 1 ~ J "!: 1 1:::::::::~ .. \_.··~i-il~ .. Comment Let the players count the points themselves and give the laser an additional task. ln the event of a tie, they both lose. l~~ ~l\ •..· ·· ..-<.·· •,• ~ j= Ji"f. f> -------,."":§;----+------- Explanation The player on the right can choose hin1self \Vhen to set off. Once the player crosses the imaginary start line, the other player can try to tap him. The person tapping has to cover the sarne course as the starting player. The starting player tries to get back over the start line. If he crosses the start line, he scores a point. Advancing The players change places each time. Explanation Player Xl plays a long ball to player X2 in the center circle. Player X2 receives the ball and tries to score. Player Xl, who passed the bali, becomes a defender and tries to intercept the bali. Only the attacking player may score. .... -·· Variation The defender can also score. Comments The players get a point by scoring a goal Advancing X2-X1-X2 • • • • Variation ln the first set, the player may only run up to the second row. He can then sprint one row further each time. Comment Let the players count the points themselves and give the laser an additional task. ln the event of a tie, they both !ase. Advancing The players change places each time. When the player gets back, he takes the ball he has kicked and replaces it ready for the next player. • • • 1 121 FITNESS IN SOCCER Fitness testing FITNESS IN SOCCER Speed, agility and quickness {SAQ} and repeated sprint ability {RSA} SUMMARY Speed of movement is one of the most important components of soccer. Professional players are getting quicker and quicker over time, meaning that sprinting ability and the ability to control speed is becoming more important in the modem game. Therefore, soccer players should perform specific exercises in order to improve their acceleration, maximum sprinting speed, and change of direction capabilities. By simultaneously improving maximal sprinting speed and endurance, a player can also improve repeated sprint ability, which enables him to perform to his maximum during intense periods of match play. FITNESS TESTING Jan Van Winckel, Kenny McMi/lan, Jean-Pierre Meert, Balder Berckmans, Werner Helsen REFERENCES Andrzejcwskl, M., Chmura, J., PJu\'1, B., Strzekzyk, R. and Kaspr.i:ak. A., 2013. Analysis of sprinting actlvilies of profcssional socccr playcrs.J Strength Cond Res, 27(&), pp.2134-2140. Balyi, !. and Hamilton, A., 2001. L.ons-tenn athlclc devclopment: Train.1bilily in dlildhood and adoles«!n<:e. Windows of opportunily. Optimal trainabi!ity. Victoria, BC: National Coacl>ing Jru;litutc llritbh Columbia & Advanred Training and Performance ltd. llangsbo, j., Mohr, M. and Krustrup, P., 2006. Physka! and mctabolk demands of tr.lining and malch·p!ay ln thc cli1c football playcr. Joumal ofSports Scienll.'s, 24(7), pp.665-67-1. llishop, D. and Spenll.'r, M., 2004. Ddcrminants of "'f"'aled·sprint abfüty ln wcll·traincd tcam-sport alh!e!e:; and cndurancc-traincd alhlct<;S. JSport~ Med Phys Fitncss, 44{1), pp.1-7. llbhop, D., Girard, O. and Mendcz-Villanucva, A., 2011. Repeatcd-Sprint Abi!ity- Part !! Rcrommcndatioru; forTraining. Sports Mcd, 41(9), pp.741-756. Bishop, D., Edgc, J., Thomas, C :1nd Mcrcicr, C., 2003. Effocts of high·intensity trnining on musdc Jactatc tr11nsportcrs and postcxcrci!'C rerovcry of musde lacta te and hydrogen ions in women. Am J Physiol Rcgu! lnt•'Sr Comp Physiol, 295, pp.R1991-<l. Dloomfidd,J., Polman, R., O'Donoghue, P. and McNaughton, L, 2003 or2007. Effoctivespecd ;md agility ronditioning methodology for random intermittent dynamic type sports. j. Strenglh Cond. Res., 21(4), pp.1093-1100. Bogdanis, G.C., Nevill, M.E., !loobfo, LH. and Lakomy, H.K., 1996. Contribution of phosphocrcatine and nerobic metaboli:Jm to cncrgy supply during repoalcd sprint excrcisc. J Appl Physiol, SO, pp.676-&I. Cavagna, G.A~ Heglund, N.C. and T:>ylor, C.R., 1977. Mochanicnl work in \crrestrial loromotion: two basic mcchanioms for minimizing energy expcnditutc. Am. J. Physiol., 233, pp.R243-Il261. Odiai, A. nnd Wong dei, P., 2013. Rcpcatcd Sprint and Changc-of·Dircction Abilities inSocccr Pbyers: Efiects of Age Group. J Strength Cond Res, 27(9), pp.25(}.t-2503. Donclnn, J.M., Krnm, R. :>nd Kuo, A.D., 2001. Mcchanical and mdabolic dctcrminanls of thc prefcrtcd stop width in human walking. Prore<:dings ofthc Royal Society !l: Bio!ogkal Sden=, 263, pp.19115-1992. Hasclcr, LJ ., Hogan, M.C. nnd Richardson, R.S., 1999. Skcktnl mundc phosphocreatinc recowry in excrci&i..'-trnincd humans is dependcnt on 02 1wallnbility. JAppl Physiol, 86, pp.2013-S. Haugcn, T., Tonn~>socn, E., Hisdnl, J. nnd Si>ilcr. S., 2013. Thc Role and Development of Sprinting Specd in Socccr. !nt J Sporl~ Physiol Pcrfom1, [Epub ahend of print]. Jovanovic, M., Spori~, G., Omn:cn, D. nnd Fiorenli1li, F., 2011. Eficcts oi spc;;:d, agilily, quickncss training mcthod on power performance in elite socccr playern. J Strength Cond Res, 25(5). pp.1285-1292. tittk·, T. :1nd Williams, A.G., 2005. Spccifkity of ncll.'lcration, maidmum spc'\!d, nnd ngility in profc:;.,ional socrer plnycro. j. Strcnglh Cond. Res., 19(1), pp.76-78. L.ockie, R.G., Murphy, A.J., Schu!t:, A.!l., Jcflries,>, M.D. nnd Callílghan, S./ ., 2013, lnfiucnll.' of sprint acrclcration otnnre kinclics on vclodty and s\ep kinematio.; in field sport athlcl.,,;.J Strength Cond Rcs, 27(9), pp.2494-2503. /\fann, R. and Sprague P., 1950. A kinctk analy$iS of the ground leg during sprint running. Res Q Excrc Sport, 51{2), pp.334-48. Moreno, E., 1995. Dcvcloping qukknes,; pari 2. Strenglh and Conditioning. 17, pp.35-39. Nirola, T.L. andjcwison, D.J., 2012. The Anatomy and lliomechanics ofRunning. Clinical]oumal ofSpor\5 Medicine, 31, pp.167-201. Pcrroni, F., Corvino, M., Cignitli, L. and Minganti, C., 2013. RSA rcsponsc to pn.-:;ca:;on \ralning in scmiprofe~sional ,;ocrer pfoyero. Sport Scicnn_'S for Hcalth. 9, pp.59·64. Ponl<.cr. H., Holloway, J.H. 4th. Rakhlcn, D.A. and Licbcrman D.E., 2009. Control 11nd function of arm swing in human walking and running. ThcJoumal of E><pcrimcntul Bio!ogy, 212, pp. 523-534. Rampinini, E., !lishop, D., Ma reora, S.M., Ferrari !lravo, D., S=i, R. and Impclliu:cri, F.M~ 2007. V.1lidity of simplc ficld ter.!!! as indkators of match·relakd physica! performnnre in top· leve! professional socrcr players. Int JSports Mcd, 28, pp.228-35. S.1ndcr, A., Kcincr, M., Wirth, K. and Schmidtblcichcr, D., 2013. lnfluençc of" 2-ycar strenglh tralning programmc on powcr performanre in clitcyouth socccr playcrs. Eur J SportSd, 13(5), pp.4.\S.51. Shcppnrd, ).M. and Young, W., 2011. Tralning agi!ity and ch11ng<>-of-direction r.pccd (CODS). Jn; M. Cardinalc, R. Newton and K. Nosaka, cds. 2011. Strength .1nd Conditioning: !liological Princip!esand Practioil Applications. Wllcy-!llackwell. pp.363-376. Shcppard, p,t. and Young. W.B., 2006. Agility lítemture rcview: Clamlfications, trnining and tcsting. Joumal of Sports Sdcnces, 2·1{9), pp.919-932. Sloth, M.,Sloth, D., Ovcrgaard, K. and Oa!gar,, U., 2013. Effccts of sprint inlcrva! \rüininp; on V02max and aerobkcxercisc performance: A systcmatic rcvicw and meta-analysis. Scandinavian Joumal of Medicine nnd Scicncc in Sports, 23(6), pp.c341-<'352. T~iGkarsio, G., Theoharopoulus,A. nnd Gnrefb, A., 2003. Spced, opced dribblc and agi!ity of mate baEkctbal! playcrs pl~ying lndiffcrent positions.Joumal of Human Movcmcnt Studics, ·15, pp.21-30. Varlcy, M.C., Gabbelt, T. and Aughey, R.J., 2013. Activity pro files of profcsoionnl wcccr, rugby !cague and Auotralian foolbal! malch play. J SportsSd., Si>p9 [Epub ahcad of print]. Weyand, P.G., Stemlight, D.13., llcllizú, M.J. and Wright, S., 2000. Fastcr top running spceds are achic1·cd with grcalcr ground forces not more rapid lei; movcmcnW. )ou mal of Applied Physiology, S9(5), pp.1991·1999. Young, W. :1nd Rogers, N., 2013. Effccts of small-sidcd game and d1ange-of·direction training on reacti1·e agility and chani;c-<lf.Jirection 5pced.Joumal ofSports Sdcnees, !Epub ahead of print 9 Si>plcmbcr]. Young, W.B., McDowcll, M.H. and ScarlcU, !l.J., 2001. Sf"'dfidty of sprint and ngilily trnining mcthods. ]oumal of Strength and Conditioning Rc-oearch, 15{3), pp.315-319. 8.1 INTRODUCTION Monitoring the physical abilities critica! to soccer performance allows sports scientists and coaches to gain valuable information that can be subsequently used effectively to optimize training and recovery. However, in complex sports like soccer, the ability to isolate and evaluate specific physical abilities can be problematic. The physiological and mechanical demands of soccer require players to be proficient in numerous aspects of fitness, such as aerobic and anaerobic power, muscle strength, flexibility, speed, agility and quickness (Reilly and Doran, 2003). These physical demands can vary according to playing position, players' individual abilities, and the tactical guidelines imposed by the coach (Reilly, 2003). Ultimately, match analysis of physical performance (e.g., distance covered) only provides the coaching staff with a one-dimensional perspective, because players do not always maximally exert their physical capacities during match play due to factors such as tactics, score, and opposition standard. In this regard, research into elite match play has found the work rate to be associated with that of the opposing team, as well as their competitive levei (Rampinini, 2007) . The main purpose of fitness tests is to build a physical profile of the player or squad. There are also other reasons for periodic fitness tests, such as being able to objectively assess the impact of training interventions (e.g., determine if the players' physical abilities have improved over the season), as well as to inform the coaches and sports scientists when a player is ready to return to training and, more importantly, to competition following an injury. i 123 124 1 FITNESS IN SOCCER FITNESS IN SOCCER Fitness testing Fitness testing 8.2 CRITERIA Fitness testing for soccer players should meet the following criteria: • They must be objective: A test's results must be reproducible from day to day and from one rater to the next, thus minimizing any subjective interpretation. This gives the best chance of observing sensitive changes in fitness over the season (improvements and decrements). • It must be specific: A test must be specific to soccer and therefore assess physical parameters important to performance (e.g., utilize similar movements, muscle groups, and energy systems). • It must be valid: A test must actually measure what it professes to measure. • A test should not require technical competence because of the leaming effect being too great. For example, if speed is being measured, it should be measured without the ball, because the player's technical skill will influence the result of the test. • It must be comprehensible: A test must be as simple as possible to minimize learning effects and maintain reproducibility. • It must be standardized in terms of administration, organization and environmental factors. Ideally, tests should be conducted at the sarne time of day, the sarne day in the microcycle, and after a similar amount of load or recovery. Even the presence of parents or encouragement from the staff can affect the test result. • It must respect necessary recovery between tests. Coaches should be guided by the time needed for replenishment of metabolic substrates when considering the recovery time betvveen tests. Coaches should taper for at least 48 hours before conducting a test in order to reduce the effect of accumulated fatigue and allo\v players to be tested in an optimal physical condition (Viru and Viru, 2001). • It must be reliable. Intra-rater reliability is the degree of agreement among multiple repetitions of a diagnostic test performed by a single rater. Inter-rater reliability is the degree of agreement among different raters. A statistical measure of inter-rater reliability is Cohen's Kappa, which ranges in general from Oto 1.0. Larger numbers mean better reliability, and values approaching zero suggest that any agreement can be attributed to chance alone. As a rule of thumb, Kappa values from 0.40 to 0.59 are considered moderate, 0.60 to 0.79 are considered substantial, and 0.80 and greater are believed to be outstanding (Landis and Koch, 1977). o It must follow a logical arder between consecutive tests. The National Strength and Conditioning Association (NSCA) (Harman, 2008) suggests the follo\ving arder: resting and non-fatiguing tests first (e.g., resting heart rate (HRr), body composition, flexibility, and jump tests), followed by tests for agility, power and strength; sprints; local muscular endurance; and anaerobic and aerobic capacity. • Preferably, a test should measure isolated physical abilities (e.g., not speed and endurance together). A test that measures too many factors at once does not provide useful information to the coaches and sports scientists as to why the player performs well or not. It is therefore difficult to set up a specific individualized program. 8.3 WHY MEASURE? Measuring physical ability is important for both players and coaching staff for a number of reasons. 8.3.1 For lhe players Testing provides feedback about the training process. This gives players a clear understanding of their personal development. • Reference data. Tests give an indication of a player's strengths and weaknesses, with the results providing reference data for an individualized training program. This makes it possible to outline a performance profile for each player. • Tests convey information about the player's state of fitness. Playing soccer at a high levei is a strain on the body (overload principie), and this can result in overload injuries. Tests can enable overtraining to be detected. 0 A testing program is an educational process, helping the player to understand the objectives of the training program. 0 Regular testing increases the player's motivation. Being more aware of one's own possibilities will encourage the player to conscientiously follow the training program. 8.3.2 For lhe coach Setting positions. Based on the test results, the coach can designate players to playing positions where their physical abilities are best suited to match demands. For example, a player with a good acceleration and high peak running speed may be more suited to playing as a winger. 0 The test results enable the coach to create a team profile. This may give the coach a better insight into the strengths and weaknesses of his team. As an example, speed tests can give the coach an idea of the speed of his defenders, and this information can then be used to advise the defensive line on how high up the field they should initiate pressure. 0 Reference data. Test results are good indicators for the rehabilitation process. Match fitness can be checked based on earlier results. • Testing data can provide coaching staff with objective feedback on the effectiveness of a training program and enable the evaluation and adjustment of the training schedule in order to optimize results. 0 i 12s 126 1 FITNESS IN SOCCER FITN ESS 1N SOCCE R Fitness testing 8.4 TEST ENVIRONMENT The test environment and conditions must be consistent and standardized for the testing data to be interpreted correctly. For example, if an initial fitness test is conducted on the pitch in a warm environment, but the following test is carried out in an indoor air-conditioned facility with a hard-floor surface, the two tests will produce differing results. Always note the conditions in arder to simplify the analysis of the results: 0 Time (The time of day can influence the result.) 0 Equipment used (Is the time measured electronically or manually?) o Periodization phase 0 Training sessions 48 hours prior to the beginning of the test 0 The arder of the different tests • Noise pollution o Temperature and humidity • Number of hours of sleep • Emotional state of the athlete • Medication • Caffeine and other beverages • Time and contents of the last meal • Test environment • Knowledge of the test (Is there a possible learning effect? Is the test "user friendly"?) • Accuracy (such as the unit of time, distances, etc.) • Warming up (Was there enough time to warm up?) • People present (Try to keep the number of people presentas low as possible to minimize outside influence.) • Players' rnotivation (Is the player motivated for this type of test? • Encouragement (Do not allow encouragement or incentives, because these can affect the test results.) As a general rule, testing should be conducted under neutral conditions. This means a good surface and a moderate temperature with no other environmental factors that could influence results, such as humidity, rain, and so on. 8.5 THE TERMS "TO BE" AND "AS IS" These two terrns are used in sporting circles to determine the demands of the sport and measure the current status. In other words, "to be" is an analysis of the sport and the physical abilities required, while "as is" represents the current state of the player for each of these abilities. For exarnple, "to be" could be that a winger has to run 1,000m at high intensity during a rnatch. The "as is" is then determined by looking at how many meters the player actually ran. For instance, if the player only ran an average of 800rn during matches, the difference between "to be" and "as is" is then 200m. This implies that the player has to work on his fitness to make up the difference between the two values. Fítness testing 8.6 TESTS Different tests that can be used to determine the team's current status ("as is") are described below. We now describe examples of muscular endurance, power, sprint, repeated sprint, agility and endurance tests that can provide useful information on the fitness status of soccer players. 8.6.1 Muscular endurance tests Introduction Augustsson et al. (2009) demonstrated that males performed significantly more push-ups than females and had 44% greater upper-body strength endurance. They also stated that females who trained upper-body strength were more likely to avoid injury. Kennedy et al. (2012) confirrned this when they suggested that athletes with limited upper-extremity endurance, as demonstrated by low push-up performance, were more likely to be injured. Wann up The standardized warrn up for muscular endurance tests should be: Five minutes jogging followed by a dynamic activation of the deep musculature. Push-up or press-up test Aim: The push-up test is used to evaluate upper-body endurance, specifically the pectoralis major, anterior deltoids, and triceps (Hoffman, 2006). Protocol: Many variations on push-up tests exist, such as the duration of the test, the placement of the hands, how far to go down, and so on. The push-up test is conducted with a normal hand and foot support position, and the body and legs are in a straight line with the feet slightly apart. The player lowers the body until there is a 90-degree angle at the elbows and then returns to the starting position. The back must be straight at all times, and the player has to continue the upward movement until his arms are fully extended. Result: The number of repetitions are counted until exhaustion or until the player is unable to maintain the proper technique over two consecutive repetitions. No pause is allowed at elbovv extension, anda self-selected tempo should be maintained throughout the test. Some other tests exist, such as timed tests like the two-minute army push-up test and the one-minute navy push-up test, as well as tempo tests where the push-ups are performed to the rhythm of a beep or metronome. The push-ups are performed ata rate of one push up every 3s in the cadence push-up testas part of the FitnessGram and the President's Challenge Fitness Award. Push-up test Min. Max. Stdev. Avg Elite U16 19.00ABS 46.00ABS 7.71 28.40ABS Elite U17 21.00ABS 50.00ABS 7.35 31.14ABS Elite U19 21.00ABS 75.00ABS 9.81 37.82ABS Elite U21 20.00ABS 61.00ABS 11.70 39.04ABS Elite First team 22.00ABS 76.00ABS 13.45 48.17 ABS Tab/e 8. 1: Reference data based on tests at different top clubs (TopSportsLab). J 121 lZB I FITNESS IN SOCCER Fítness testing Partia! abdo11iinal niuscle Aim: To measure the muscular endurance of the abdominal muscles and hip flexors. This provides a foundation for trunk and spine stability (Axler and McGill, 1997). Protocol: The player lies on his or her back with knees flexed at 90°. (This relieves the strain on the lo•ver back and the hip flexors are extensively immobilized.) The feet may not be anchored to the ground, and the arms should lay by the player's side with the fingers touching a line. A second line is positioned at 10 cm. The player then tries to do as many curl-ups as possible in one minute. Many methods of conducting crunches or curl-up tests have been published (e.g., feet anchored, hands crossed over the chest, legs on the ground, etc.). Some tests use a certain period (e.g., two minutes in the US Army) and some use a set tempo until exhaustion (e.g., the NHL curl-up beep). Fig. 8. 1: Abdominal muscle exercise lf the abdominal musc/e exercises are performed with extended /egs, lhe musc/es flexing the hip wilf assist in the exercise. When the knees are bent at 90º, the strength ofthe hip flexors is limited, enabling the abdominal musc/es to work in iso/ation. Parfrey et af. (2008) did not find any significant effects of knee position in muscfe activation, but they did finda trend towards greater activation of the abdominal museu/ature and /ower Rectus Femoris activation when lhe knees were bent. Result: The number of repetitions are counted. Science: Parfrey et aL (2008) examined the effects of different sit- and curl-up positions on activation of abdominal and hip flexor musculahtre. ln this study, the highest level of activation carne from the 10 cm sit-up test with non-fixed feet and bent knees as described in this book. This test provides high activation of the abdominal musculature with minimal activation of the hip flexors. FITNESS IN SOCCER Fitness testing 8.6.2 Power tests Jntroduction The jumping ability of a soccer player is considered highly important for performance. Jumping is a complex movement that greatly depends on inter-limb coordination, muscle-fiber type and stiffness, and maximum strength. Literature has shown that jump height can be improved through various types of training methods (Kotzamanidis et al., 2005). ln the literature, a range of different terms are used. ln this book, we use the following terms: Squat jump (SJ): The player starts from a semi-squat position (90°) with no arm swing and no counter movement Vertical jump (VTJ): The player starts from a stationary, semi-squat position (90º) with arm swing and no counter movement. Counter movement jump (CMJ): The player starts from an upright standing position and performs a downward movement (counter movement) with no arm swing allowed. Counter movement jump with arm swing (CMJwa): The player starts from an upright standing position and performs a fast do\vnward movement (counter movement) with arm swing. ln the literature, the VTJ is often confused with the CMJ. ln a CMJ, the player can bend his legs and make a counter movement, \Vhich will enhance the test results (jump higher) compared to a VTJ. ln addition, the VTJ is not an easy test to carry out. The player should not conduct any pre-stretching. Even minar pre-stretching may make a big difference to the height jumped. Wann up The standardized warm up for power tests is as follows: o Five minutes jogging followed by a dynamic activationof the deep musculature 0 Two submaximal jumps, a one-minute recovery, and one maximal jump followed by two minutes of recovery. Couuter 111ove111ent ju111p (CMJ) Aim: To measure the explosive, concentric strength of the legs and re-use of elastic energy during the eccentric to concentric movement. Protocol: The CMJ is performed from a standing start. The test is best carried out on a contact n1at. lf a contact mat is not available, the CMJ\va test can be conducted by measuring the reach height and then maximum height by using a Vertec ora \Vall. Three maximal jumps are done with 30s of rest between them. Instructions for the athlete: The player starts from an upright standing position and performs a fast downward movement (counter movement) with or \Vithout an arm swing. Result: The highest score i 129 130 1 FITNESS IN SOCCER FITNESS IN SOCCER 1 131 Fitness testing Fitness testing Counter Movement Jump (with Arm Swing) Min. Max. Elite U16 28.80 cm 59.00 cm 5.63 40.55 cm Elite U17 22.50 cm 59.10 cm 6.54 40.24 cm Elite U19 28.70 cm 65.20 cm 7.06 44.63 cm Elite U21 30.00 cm 65.70 cm 6.37 44.98 cm Elite First team 32.20 cm 63.90 cm 5.77 47.82 cm Elite Women first team 27.20 cm 42.50 cm 3.93 32.95 cm Stdev. Avg Counter Movement Jump Max. Min. Stdev. Avg Elite U16 21.40 53.50 4.96 34.98 Elite U17 23.80 47.10 5.09 34.26 Elite U19 24.80 60.80 6.34 38.53 Elite U21 28.30 49.90 5.24 38.91 Elite First team 28.70 59.40 4.65 42.12 Elite Women first team 25.30 34.20 2.39 28.78 VERTICAL JUMP (VTJ) AND SQUAT JUMP (SJ) Aim: To measure the explosive, concentric strength of the legs. Protocol: The SJ is performed from a semi-squat position. A total of three maximal jumps are performed with a 30s pause after each jump. ln the event of different jump tests, a five-minute rest period is taken between the different tests. The squat jump is done without arm swing (see figure 13.5). The VIJ is performed from a semi-squat position with arm swing. The test is best carried outona contact mat. If this is not available, the test can also be conducted by measuring the reach height and then maximum height by using a Vertec or a wall. Three maximum jumps are performed with a 30s rest between each attempt. Instructions for the athlete: • Knees kept at an angle of 90º before jumping o No pre-stretching permitted Result: The highest score. Elasticity index: The percentage difference between SJ and CMJ height is defined as lhe elasticity index (E!) or elasticity rate (Walshe et al., 1996). The EI provides information regarding viscoelastic and neuromuscular capacities (Pacheco et ai., 2011) Squatjump Min. Max. Stdev. Avg Elite U16 20.30 cm 53.90 cm 4.77 32.16 cm Elite U17 18.64 cm 49.40 cm 6.26 33.71 cm Elite U19 20.70 cm 53.60 cm 5.83 36.20 cm Elite U21 23.30 cm 55.70 cm 5.64 36.51 cm Elite First team 28.30 cm 53.70 cm 4.53 39.90 cm Elite Women first team 21.00 cm 35.20 cm 3.37 27.49 cm Table 8.2: Reference data based on tests at different top clubs (TopSportsLab). One-legged CMJ Left Min. Elite U16 14.50 Max. Stdev. Avg 37.36 4.32 23.59 5.21 22.65 Elite U17 11.40 38.60 Elite U19 12.60 41.50 6.10 23.16 Elite U21 17.10 43.00 4.97 27.42 Elite First team 15.80 41.30 4.89 27.68 Elite Women first team 16.20 25.20 2.85 20.06 STANDING BROAD JUMP, HOR!ZONTALJUMP OR STAND!NG LONG JUMP TEST The standing broad jump (SBJ) is an athletic event. It was even an Olympic event until 1912. A horizontal jump may be of more value to the sports practitioner, because horizontal movements occur in many sports actions such as sprinting and other agility movements. Horizontal jump tests have good reliability, and they correlate well with sprinting both kinematically and kinetically (Ball and Zanetti, 2012). Aim: To measure the explosive, concentric strength of the leg muscles. Protocol: The SBJ is a long jump from a standing position. The player jumps as far as possible, landing on both feet without falling backwards. Three jumps are carried out with a break of 30s between attempts. The player may use a counter movement. Instructions for the athlete: o Feet slightly apart behind the line o Jump as far as possible, landing on both feet It is advisable to use a mat to absorb the shock on landing. Result: The best score is measured accurately to the nearest cm with the best results being recorded. Standing Broad Jump Max. Min. Min. Elite U16 Elite U17 Elite U19 14.70 12.20 11.90 Max. 37.10 39.80 40.40 Stdev. 4.09 5.03 6.10 206.71 cm Elite U16 155.00 cm 274.00 cm 21.73 Elite U17 161.00cm 246.00 cm 21.34 196.78 cm Elite U19 185.00 cm 254.00 cm 14.53 215.00 cm Elite U21 185.00 cm 265.00 cm 16.30 226.08 cm 160.00 cm 283.00 cm 23.74 232.77 cm I I I I Avg 23.46 22.49 23.75 Elite U21 18.40 41.80 4.63 27.06 Elite First team Elite First team 18.00 39.60 4.60 27.48 Elite Women first team Elite Women first team 14.30 25.40 2.92 20.03 Table 8.3: Reference data based on tests at different top clubs (TopSportsLab). Avg Stdev. One-legged CMJ Right Table 8.4: Reference data based on tests at different top clubs (TopSportsLab). 132 1 FITNESS IN SOCCER FITNESS IN SOCCER Fitness testing Fitness testing SINGLE-LEG, TRIPLE-HOP TEST LEFT AND R/GHT (SLTHT L & R) Functional tests for an individual lower extremity-such as the Single-Leg Vertical Jump (SLVJ), Single-Leg Hop for Time (SLHT), and Single-Leg Hop for Distance (SLHD)-are used by medical staff to gain information to help decide whether a player is ready to return to full play or not. The popularity of single-limb hop tests is clearly evident inACLoutcome studies. This is not surprising given there is increased functionality over two-legged tests. The use of the healthy limb as a biological control eliminates the need to rely on population-specific normative data (Hopper et al., 2002). Furthermore, pre-injury data is often unavailable (van der Harst, Gokeler and Hof, 2007). Additionally, functional tests can be used to measure percentage deficit after an injury and monitor the effectiveness of rehabilitation (Clark, 2001). A functional deficit of 10% between limbs is accepted as a return-to-play criteria. Triple·Hop Distance Test L Mín. Max. Stdev. Avg Elite U16 410.00 cm 760.00 cm 60.67 606.05 cm Elite U17 430.00 cm 761.00 cm 62.64 586.67 cm Elite U19 470.00 cm 766.00 cm 64.98 634.38 cm Elite U21 548.00 cm 819.00 cm 53.93 678.28 cm Elite First team 531.00 cm 820.00 cm 49.58 694.52 cm Elite Women first team 466.00 cm 604.00 cm 36.41 537.00 cm Triple-Hop Oistance Test R Min. Max. Stdev. Avg Elite U16 438.00 cm 734.00 cm 56.40 599.07 cm Elite U17 398.00 cm 720.00 cm 67.13 577.38 cm Elite U19 470.00 cm 762.00 cm 67.86 637.42 cm Elite U21 388.00 cm 784.00 cm 61.20 677.48 cm Elite First team 435.00 cm 788.00 cm 48.66 688.40 cm Elite Women first team 496.00 cm 581.00 cm 24.62 534.75 cm Tabfe 8.5: Reference data based on tests at different top cfubs (TopSporlsLab). Aim: To measure the explosive, concentric strength of the leg muscles and the difference between the left and right leg. Protocol: The SLTHT is a long jump on one leg from a standing position. The player stands on one leg behind the line and hops on that leg three consecutive times, travelling as far as possible. The player lands on one leg. Instructions for the athlete: 0 Stand on one leg behind the line. 0 Hop as far as possible three times, landing on the sarne foot. 0 Use your hands and arms to the maximum. Result: The distance is recorded accurately to the nearest centimeter. The score is measured from the line to where the heel touched the ground on the last jump. The best score, as well as the average score, is recorded. Science: This test can be used as a return-to-play criteria by measuring the functional deficit between limbs. This is done using the Limb Symmetry Index (LSI) (i.e., LSI = injured leg/non-injured leg x 100). Noyes et ai. (1991) described a limb symmetry score of below 85% as being abnonnal. SEATED CHEST PASS 3 KG Aim: To measure the explosive, concentric strength of the arm muscles. Upperbody power has been quantified using various medicine ball throw tests, including the seated chest pass (Vossen et ai., 2000; Cronin and Owen, 2004). Protocol: The seated chest pass is a maximal throw with both hands from a sitting position. The player sits against a wall with a straight back and extended legs while holding a 3 kg medicine ball in front of his or her chest. The player throws the ball as far as possible using both hands. The player performs three throws, and the best score is recorded. Instructions for the athlete: o Sit with your back against the wall. o Keep your legs straight and close together. 0 Hold the ball in front of your chest with both hands. o Throw the ball as far as possible. Result: The distance is recorded accurately to the nearest cm. The score is measured from the line to where the bali made contact with the floor. 8.6.3 Sprinting speed Introduction According to Little and Williams (2005), high-speed actions during soccer competition can be categorized into actions requiring acceleration and deceleration, maximal speed, and agility. Acceleration is the rate of change in velocity that allows a player to reach maximum velocity in the minimum amount of time. On the other hand, deceleration is the rate at which a player can slow down. Maximum speed is the maximal velocity at which a player can sprint. The range of sprint distances documented during games (from l.Sm up to lOSm) indicates the need for both acceleration and maximum speed abilities. The literature states that acceleration, maximum speed, and agility are specific qualities that are relatively unrelated to one another (Bangsbo, 1994; Little and Williams, 2003). Importantly, the results of sprint tests have been shown to differ between different positional roles within the team (Kollath and Quade, 1993). Wann up Standardized warm up for sprint tests: Five minutes jogging Five minutes of dynamic stretching Two submaximal sprints of 20m, a one-minute recovery, and one nearly maximal sprint of 40m followed by two minutes of recovery. 10, 20, 40m sprint test Aim: To measure acceleration (lOm) and maximum running speed (40m). Protocol: Draw a starting line and set up the photoelectric timing gates at 10, 20and40m. 1 133 134 FITNESS IN SOCCER Fitness testing 1135 [ FITNESS IN SOCCER Fitness testing The player runs the set distance as quickly as possible. The test is conducted three times, with a rest period of tw"o minutes betw'een each sprint. The player stands with one foot 50cm behind the first electronic gate and decides when to set off (to eliminate reaction time). It is important for the player to run at full pace through the final 40m electronic timing gate. Electronic measuring equipment is essential for all tests, because the distances for soccer-specific sprint tests are too short to be measured manually. Double beam timing gates should be used if possible. The timing gates should be set at waist height, because this prevents an extended arm or leg from causing an incorrect time to be recor<led. Result: The time is recorded to the nearest 1/lOOth of a second, with the best time being noted. Acceleration index = 20 m - 10 m sprint time Maximum speed index = 40 m - 20 m sprint time 8.6.4 Repeaied sprint ability BANGSBO REPEATED SPRlNT TEST (J:"·\ ~ i : A A : A 40m A ··---";;;,> A.,.._,, Max. Stdev. Avg ............. ?> Elite U16 1.66 sec 2.22 sec 0.12 1.90 sec Elite U17 1.57 sec 2.28 sec 0.11 1.90 sec Elite U19 1.57 sec 2.24 sec 0.14 1.86 sec Elite U21 1.51 sec 2.15 sec 0.14 1.81 sec Elite First team 1.49 sec 2.05 sec 0.10 1.76 sec Elite Women first team 1.99 sec 2.19sec 0.06 2.08 sec Sprint test 20m Max. Stdev. Avg Elite U16 2.83 sec 3.87 sec 0.20 3.27 sec Elite U17 2.92 sec 3.93 sec 0.18 3.28 sec Elite U19 2.69 sec 3.85 sec 0.25 3.16 sec Elite U21 2.66 sec 3.67 sec 0.21 3.08 sec Elite First team 2.72 sec 3.46 sec 0.13 3.02 sec Elite Women first team 3.41 sec 3.89 sec 0.12 3.58 sec Sprint test 40m Elite U16 Speed gate \ •...•..:v Sprint test 1Om Min. Sm Sm  Min. Speed gate Stdev. Avg Min. Max. 5.06 sec 6.87 sec 0.37 5.84 sec Elite U17 5.20 sec 7.00 sec 0.36 5.86 sec Elite U19 4.81 sec 6.82 sec 0.44 5.60 sec Elite U21 3.94 sec 6.53 sec 0.47 5.38 sec Elite First team 4.81 sec 5.96 sec 0.22 5.36 sec Elite Women first team 6.06 sec 6.98 sec 0.22 6.43 sec Tabfe 8.6: Reference data based on tests at different top cfubs (TopSportsLab). Sprint Active recovery Bangsbo, 1994 • LED Wragg et ai. 2000 Fig. 8.2: Bangsbo repeated sprint test Aim: To measure soccer-specific repeated sprint ability (Bangsbo, 1994}. Protocol: The protocol includes seven successive 34.2m maximal sprints, including a slalom. The players start with their leading foot 0.3m behind the starting line. A period of active recovery (25 s to cover the 40m back to the starting line} is given after each sprint. Guidelines: 0 Make the player run the course twice as part of the warm up. 0 Emphasize that: - the distance between A and B has to be run at maximum speed - the player has to return to the starting line on time 0 Two observers are needed: one at the starting line and another at the finish line. The first one calls out "2-1-go," signaling these three stages by first extending his arm, then bending his elbow to raise his forearm at an angle of 90º, and then lowering his forearm to a completely horizontal position. The second observer then starts the stopwatch and records the time. " The player performs seven sprints in total. 0 Testing an entire team takes approximately an hour. Result: The time is measured accurately to the nearest 1/lOOth of a second, with the best time being recorded. The mean time is the average of the seven sprints. This time indicates the player's ability to perform severa! sprints within a short period. The fatigue index is calculated by deducting the fastest time of the first two sprints from the slowest time of the last tvvo sprints. A high fatigue index suggests the player shows inconsistency in sprint performance, and this represents the player's inability to recover during repeated sprints. A high fatigue index may reflect an inability to replenish phosphocreatine stores 136 FITNESS IN SOCCER 1 FITNESS IN SOCCER Fitness testing Fitness testing and adequately remove blood lactate between consecutive sprints (Tomlin and Wenger, 2001 ). Wragg et aL (2000) used a modified version of the Bangsbo sprint test. Their modification involved adding a random right or left turn component to improve the applicability to the vari-directional nature of team sports and to place a demand upon both legs. The change of direction was shown using two light-emitting diodes (LED). MODIFIED ILLINOIS AGILITY TEST 5m 8.6.5 Agility Introductio1z lOm Mirkov et al. (2008) investigated the reliability of soccer-specific field tests and postulated that the most appropriate indicator of overall soccer performance may be agility testing. A soccer player changes direction every 2-4s (Bangsbo, 1992). This was confirmed by Verheijen et al. (2010) when they reported that players make 1,200-1,400 direction changes during a game. Speed gate  Speed gate Fig. 8.4: Moditied Illinois agility test War11t up Standardized warm up for agility tests: Five minutes jogging followed by a dynamic activation of the deep musculature Two submaximal sprints of 4x5m shuttle, one minute of recovery, and two maximal sprints of 3x10m shuttle followed by tvvo minutes of recovery THE 505 AGILITY TEST A B e Illinois agility test Min. Max. Stdev. Avg Elite U16 14.22 sec 17.08 sec 0.59 15.27 sec Elite U17 14.68 sec 16.99 sec 0.59 15.38 sec 14.85 sec Elite U19 14.00 sec 16.18 sec 0.57 Elite U21 13.85 sec 15.84 sec 0.55 14.71 sec 0.37 15.19 sec Elite First team 14.63 sec 15.61 sec Tab/e 8. 7: Reference data based on tests at different top clubs {TopSportsLab). ( 1 J. Fig. 8.3: The 505 test Aim: Measuring agility (i.e., change of direction). Protocol: The player runs from point A to point C and back to A as fast as possible. The player must step past the turn line with both feet before retuming to the start. The time is recorded from when the player first runs through the Sm marker (B) to when they return through this marker (i.e., the time taken to cover the Sm there and back, lOm in total). Result: The score is determined by recording the time to the nearest 1 / lOOth of a second. Each player has three attempts, with only the best time being noted. Aim: To test agility (Getchell, 1979). Protocol: The course is lOm long and Sm wide. The cones in the center are placed 3.3m from each other. ln the original protocol, players were asked to begin in a prone position at the starting cone. Since this is an unnatural position for a soccer player, we have instead chosen to start in a standing position 30 cm behind the first timing gate. Result: The score is determined by recording the time to the nearest 1/lOOth of a second. The player runs the course tvvice, both from the left side, with a minimum of three minutes betvveen the tvvo attempts. The best time is recorded. Science: Caldwell and Peters (2009) examined seasonal variations in physiological fitness. The authors found that both sprint and agility performance decreased significantly during the off-season period. This is supported by Ross and Leveritt (2001), who identified that detraining caused a decrease in speed performance over 10-20m. 1 137 l3S I FITNESS IN SOCCER flTNESS IN SOCCER Fitness testing Fitness tesiing MODIFIED T TEST LEFT AND RIGHT Modified Agility T-test Left Min. Sm lOm Elite U16 Speed gate  l  Sm lOm  Speed gate 1 JÍâ À, Speed gate Â, Max. 10.86 sec Stdev. 0.37 Avg 9.51 sec Elite U17 8.75 sec 11.00 sec 0.45 9.59 sec Elite U19 8.38 sec 10.59 sec 0.48 9.38 sec Elite U21 8.41 sec 10.27 sec 0.38 9.32 sec Elite First team 8.48 sec 10.85 sec 0.43 9.22 sec E!ite Women first team 9.80 sec 11.05 sec 0.32 10.23 sec Speed gate Table 8.8: Reference data based on tests at different top c/ubs (TopSportsLab). AgilityT-test Sassl et a!. 2009 ModifledT·test 8.56 sec Fig. 8.5: Modified T test /eft HEXAGON AGILITY TEST Aim: To measure speed and agility. Protocol: The player runs the course as quickly ª"' possible, from point A in the direction of B, C, D, and B before returning to the start. ln contrast to the protocols outlined by Paulole et al. (2000) and Sassi et al. (2009), the course may be covered in as natural a way as possible without shuffling or running backwards, since neither movements are used often in soccer and are not determining factors. Sassi et al. (2009) proposed another modified agility T-test. The researchers indicated that this new version of the T-Test (MAT), obtained by reducing the total distance covered, presents a good relative and absolute reliability for both men and women. The nature of displacements in sports like volleyball, basketball, and tennis cannot be replicated by using the standard T-Test, because they are based on very short repeated displacements. They concluded that the MAT would provide a more specific measurement of agility for these sports. However, for activities practiced on large courts or fields, such as soccer and rugby, the use of the T-test would be more adequate and is recommended. Result: The test is performed both from the right and the left. The score is determined by recording the time to the nearest 1/lOOth of a second. The best time is noted. Science: Pauole et ai. (2000) investigated the reliability of the T-Test, finding it to be a highly reliable test that measures a combination of components, including leg speed, Ieg power, and agility. The T-Test may be used to differentiate between those of low and high leveis of sports participation. Modified Agllity T-Test Right Min. Max. Stdev. Avg Elite U16 8.29 sec 10.56 sec 0.38 9.55 sec Elite U17 8.77 sec 11.37 sec 0.47 9.68 sec Elite U19 8.52 sec 10.71 sec 0.49 9.44 sec Elite U21 8.03 sec 10.63 sec 0.47 9.44 sec Elite First team 8.53 sec 10.95 sec 0.40 9.27 sec Elite Women first team 9.58 sec 10.74 sec 0.28 10.02 sec --------------------------""""' Beekhuizen et al. (2009) investigated the test-retest reliability of the Hexagon Agility test. The researchers concluded that the hexagon test shows excellent reliability for measuring agility, supporting its use as a tool to measure athletic performance and lower-extremity agility. This high levei of reliability, in addition to its ease of administration, makes the hexagon testa practical and Fig. 8.6: Hexagon agi/ity test effective method to measure quickness. Additionally, the researchers suggested that while using this test, a change of greater than 1.015s is necessary to be 95% certain that this change intime reflects improvement and exceeds measurement error. A practice triai is recommended prior to recording scores to reduce the possibility of a leaming effect. 00 00 Aim: This test measures lower extremity agility and quickness. Protocol: Draw a regular hexagon (internai angles of 120°), with the sides being 60.Scm (2 feet) long. The test begins with the player standing on a line placed in the middle of the hexagon. The test starts when the tester gives the command "Ready, go!" and starts the chronometer. The player tries to con1plete three rounds as quickly as possible by jumping two-footed over each side. The player keeps his head and body facing in the sarne direction all the time. The test is carried out in both a clockwise and anti-clockwise direction and performed three times in each direction with lOs of recovery in between. There is also a minimum of five minutes rest between the clockwise and anti-clockwise tests. If the player touches the line, the triai is stopped and restarted (Baechle and Earle, 2000). Result: The score is determined by recording the time to the nearest 1 / lOOth of a second. The best time is recorded. A comparison between the clockwise and anticlockwise tests may reveal an imbalance between left and right movement skills. 1139 140 1 FITNESS IN SOCCER 1 FITNESS IN SOCCER Fitness testing Fitness testing 8.6.6 Modified 300m Shuttle Tempo Test Anaerobic Capacity tests Min. Warnz up Standardized warm up for measuring anaerobic capacity: • Five minutesjogging followed by a dynamic activation of the deep musculature • Four submaximal sprints of 50m followed by two ffiinutes of recovery MOD!FIED 300m SHUTTLE TEMPO RUN Maximally accumulated oxygen deficit (MAOD) has been argued to be the best noninvasive method for estimating anaerobic capacity (Scott et al., 1991; Ramsbottom et al., 1997). An easy-to-administer field test that could accurately predict MAOD would be of great use to many field-sport athletes and coaches. Moore and Murphy (2003) concluded that the 300m Shuttle Run Test is a useful estimate of anaerobic capacity in soccer players. Elite U16 Max. Stdev. Avg 57.03 sec 73.23 sec 3.21 Elite U17 56.30 sec 66.03 sec 2.19 60.46 sec Elite U19 55.44 sec 65.38 sec 2.19 59.45 sec 62.24 sec Elite U21 52.90 sec 80.10 sec 4.75 58.71 sec Elite First team 53.06 sec 63.53 sec 2.21 57.17sec Elite Women first team 65.50 sec 75.69 sec 3.18 70.26 sec Table 8.9: Reference data based on tests at different top c/ubs (TopSportsLab). 8.6.7 Endurance tests som lOm Fig. 8. 7: Modified 300m shuttle tempo test Aim: To measure acyclic anaerobic endurance capacity (shuttle tempo test). Place: Artificial field. Warm-up: cardiovascular stimulus (five minutes running), followed by dynamic stretching exercises, and finally, a few submaximal sprints. Protocol: The player runs to the lüm line and back, then to the 20m, 30m, 40m and Süm lines. The player has to cross each line with at least one foot. Two observers are needed, with one standing by the starting line and recording the time. The other observer moves constantly from the lüm líne to the 20m líne (and so on}, checking that the player passes the line and ensuring there is no confusion about the distance to be covered. Different protocols are used in the literature, such as a 300m shuttle tempo test and a shuttle test of 300m over a 20m distance (Moore and Murphy, 2003). During the 300m shuttle run test, the players must run to the 25n1 mark, touch it with a foot, turn, and run back to the start. This is repeated six times without stopping (Sporis et al., 2008). Result: The score is determined by the time recorded to the nearest 1 / lOOth of a second. 20m SHUTTLE RUN TEST The 20m shuttle run test was developed by Léger and Lambert in 1982. Aim: The 20m shuttle run test is used to analyze acyclic endurance capacity. The test measures cardiorespiratory endurance by means of a progressive maximum test. Protocol: Set out tvvo lines 20m apart, with a reference line 3m in front of each line. A CD player anda compact disc of the Léger protocol are used. Instructions for the tester: The starting speed is 8 km/h, with 0.5 km/h added every minute. The intervals are indicated by audible signals. The aim is to start atone of the tvvo lines 20m apart each time the signal is given. Instructions for the athlete: 0 Each player runs at the sarne pace (i.e., not faster or slower than the audible signal). 0 One foot needs to touch the line. 0 If a player touches the line before the signal is given, he has to wait to set off again. 0 A player must stop if: he ar she gives up - he or she does not touch the finish line three times - he or she is not at the 3m line at the moment the audible signal sounds. ° Keep at least lm distance betvveen the players. Result: The time is recorded when the player stops. 141 142 1 FITNESS IN SOCCER Fitness testing FITNESS IN SOCCER Fitness testing YO-YO INTERMITTENT RECOVERY TEST The Yo-Yo intermittent recovery (Yo-Yo IR) test was first described in Fitness Training in Soccer, a scientific approach by Jens Bangsbo (1994). There are two versions of the Yo-Yo Intermittent Recovery Test: a Level 1 for beginners and an advanced levei 2. Both tests evaluate players' abilities to repeatedly perform intense exercise. The Yo-Yo IR level 1 (Yo-Yo IRl) test focuses on the capacity to perform intermittent exercise, leading to a maximal activation of the aerobic system, whereas the Yo-Yo IR levei 2 (Yo-Yo IR2) test determines an individual's ability to recover from repeated exercise with a high contribution from the anaerobic system. Evaluations of elite athletes in various sports involving intermittent exercise showed that the higher the levei of competition, the better an athlete performs in the Yo-Yo IR tests (Bradley et ai., 2010; Krustrup et ai., 2006). The Yo-Yo IR tests have been shown to be a more sensitive measure of changes in performance than V02m""" providing a simple and valid way to obtain important information about an individual's capacity to perform repeated bouts of high-intensity exercise. Furthermore, high correlations were found between Yo-Yo IR test performance and the distance of high-intensity running during a soccer match, which was not the case for other tests, such as repeated sprint tests, the V02m,,x test, and the 20m shuttle run test (Krustrup, et ai., 2003; Bangsbo j. et ai., 2008). Thomas et ai. (2006) investigated the correlation between the Yo-Yo IR test and the 20m shuttle run test and V0 2max· The investigators concluded that the level 1 (recreational) and level 2 (elite) test scores both strongly correlated with the 20m shuttle run (Léger and Lambert, 1982) scores and vo2max (level 1 recreational subjects only). Estinwtes of V0 2,,,,.,,: Yo-Yo IR1 test: V0 2111 _,,, (111L/111i11/kg) = IR1 distance (m) x 0.0084 + 36.4 Estilnates ofV0 2 ,,,~x: Yo-Yo IR2 test: V0 2111ax(1nL/11lin/kg) = IR2 distance (111) x 0.0136 + 45.3 20m Sm ~    À À À  À À À      Fig. 8.8: Yo-Yo intennittent test recovery test Aim: For a trained player, the Yo-Yo IRl test lasts 10-20 minutes and is mainly focused on an individual's endurance capacity. ln contrast, the Yo-Yo IR2 test lasts 5-15 minutes and tries to evaluate a trained player's ability to perform a repeated intense bout with a high anaerobic energy contribution. The Yo-Yo IR1 test achieves these criteria for a lesser trained player (Bangsbo et al., 2008). Protocol: The Yo-Yo IR tests consist of two 20m shuttle runs at increasing speed with a ten-second (2 x 5m) period of active recovery between that is controlled by audio signals. A player should run until they are unable to maintain the speed, and the total distance covered at this point is the test result. A warning is given whenever the player does not complete a shuttle in time, and the player must stop if they do not complete a fuil shuttle the next time. There are two leveis to the test. Level 1 (Yo-Yo IR1) starts ata lower speed, and the increases in speed are more moderate than in the level 2 (Yo-Yo IR2) test. Instructions: 0 Each player runs at the sarne pace (i.e., not faster or slower than the audible signa!). 0 Walk slowly around the cone and set off again when the signal is given. 0 The test must be stopped after a second warning has been given by the tester. o A11ow at least lm of space per player. Result: The level and total distance are noted. Mohr and Krustrup (2013) investigated Yo-Yo intermittent recovery test performances within an entire soccer league (of semi-professional players) during a full season. YYIR2 performance was 847 ± 227m at preseason. It rose by 128 ± 113m to 975 ± 205m at the start of the season, rising further by 59 ± 102m to 1034 ± 2Ilm at mid-season. Submaximal YYIR1 HR was 90.9 ± 4.2% HRm"" at preseason, higher than at the start, middle and end of the season (87.0 ±3.9, 85.9 ±4.1, and 87.0 ± 3.7% HRmJx respectively). Peak YYIR2 performance and minimum YYIRl HR were 1068 ± 193 m and 85.1±3.8% HRmax respectively, with around 50% of the players peaking at mid-season. 1 143 FITNESS IN SOCCER Fitness testing FITNESS IN SOCCER Fitness testing 30-15 INTERMITTENT FITNESS TEST (30-15 IFT! The 30-15 Intermittent Fitness Test (30-15 IFT) was designed by Buchheit (2008) to replicate the intermittent demands of soccer. This test differs from the Yo-Yo IR tests, however, in that it involves 30s of running followed by 15s of walking. 40m - 20m 3m ' 1 1 1 1 LlneA 1 Line B Line e ............................................ Players line up behind one of the end lines (line A). They begin to run on the first "beep," pacing their efforts so they will be within the 3m mark of line B at the second "beep." They then arrive at the next 3m mark (line C) at the third "beep." This continues until there is a different, double beep that indicates the end of the 30s exercise period. Active recovery is then commenced for the next 15s by walking forwards to the next line and waiting for the next 30s running period to begin. The test is terminated when participants reach volitional exhaustion or when an athlete does not make it into the tolerance zone three times. Score: The running velocity during the last completed stage is recorded as the maximum running speed (vIFT). The vIFT is also useful for the prescription of generic running drills to improve RSA. The following formula estimates V0 2max based on the final running speed. G stands for gender (female = 2; male =1), A for age, and W for weight (Buchheit, 2008). vo,m" (ml/kg/min)= 28.3-(2.15 x G)-(0.741 xA)-(0.0357 x W) + (0.0586 xAx v!FT) + (1.03 x v!FT) Sprínt 0 ., .......... l> Aclive rccovery Fig. 8.9: 30-15 lntermittent Fitness Test Aim: To measure the ability to recover and repeat intermittent activity Procedure: Mark a 40m area with cones at each end and also at the midpoint (20m). Place cones 3m before each end line and either side of the míd-line (tolerance zones). The test consists of 30s shuttle runs interspersed with 15s passive recovery periods (i.e., walking) on a 40m straight runway. The running velocity starts at 8 km/h, increasing by 0.5 km/h at every 45s stage thereafter. As a result, depending on the speed, the participants have to cover an increasing distance for a given time. FOUR-MINUTE SUB-MAXIMAL TEST ln this test, the players run on a motorized treadmill (or use a bike if a treadmill is unavailable) at 12 km/h for four minutes. At the end of the four minutes, both the HR and heart rate recovery (HRR) after 30, 60 and 120s are recorded. This makes it possible to see if a player has recovered well (the HR is lower) and whether his fitness has improved (the HR is lower and HRR is quicker). This test is ideal for monitoring the fitness and recovery of players. It can be performed daily and is easy to administer and carry out. 8.7 ANALYZING TESTING RESULTS It is clear that regular testing of soccer players is advantageous to coaching staff. It allows coaches to assess the fitness leveis of players and plan appropriate training throughout the season. However, once a battery of tests has been performed, it is the job of sports scientists in the support staff to analyze changes in physical performance longitudinally across training periods and seasons. It has been suggested that analyzing the percentage difference between repeated tests is a more appropriate method of assessing athletic performance (Hopkins et al., 2009). This method of analysis also allows for clear comparisons to be made between changes in different physical abilities, something that is difficult with raw data. For example, considera 5% increase in CMJ and a 7% decrease in 40m sprint time rather than a 3cm increase in CMJ and 0.Ss decrease in 40m sprint time. Using percentage differences allows for more meaningful and clear conclusions to be made about physical abilities. 1 145 FITNESS IN SOCCER FITNESS IN SOCCER Fitness testing Fitness testing Additionally, a method for assessing the true change in athletic performance using the smallest worthwhile change (SWC) statistic has been suggested (Batterham and Hopkins, 2006). This is calculated by multiplying the between-player standard deviation by 0.2. This creates a raw data unit that a player must meet in arder for an improvement in performance to be substantial. Again, this can then be made into a percentage SWC. Test 1 Re-Test o/o Change Player 1 1800 1900 5.6o/o Substantial improvement Player 2 1850 1830 -1.1o/o Trivial decrease Player 3 1900 2200 10.So/o Substantial improvement Player4 2000 2300 1°/o Trivial improvement Player 5 2100 2000 -7.1% Substantial decrease Player 6 1750 2000 0% No lmprovement Playcr 7 1800 1950 8.3% Substantial improvement Average 1885.7 1928.6 2.3°/o Substantia! improvement in team performance Standard Deviation 124.9 swc 25 o;..swc 1.3% 116.3 Tab/e 8.10: Exampfe of an intermittent performance test using the SWC. The SWC statistic al/ows sporl science and supporl staff to categorize changes in performance and make meaningful conc/usions about individual and team performance over time. SUMMARY By monitoring the physical abilities of soccer players on a consistent basis, sports physiologists and soccer coaches can gain valuable information that can be then used effectively to optimize training and recovery. The tests chosen must be specific, valid, and reliable. 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Thomas,,\., Dawson, a. nnd Goodman, C., 2006. The yo-yo tc-;t: rcliability and =iodation wilh n 20-m ~hultlc run and V02mnx. Intcrnational Joumal of SporW Phyüiology and Pcrfonnancc, 2, pp.137·149. Torn!in, D.L. and Wcngcr, H.A., 2001. Thc rclationship hetwcen acrobk fitncss and rccovcry frorn high inleru;ity inlcnnittcnt cxcrcise. Sporw Medicine, 31(1), pp.l-11. van der Hars!, J.J., Gokclcr, A. and Hof, A.L., 2007. Lcg: kincrni!tks and kinctko in landing from a ~ingk'-lcg hop for di<tancc. A rornp.1rison bctwccn dorninont nnd non-dorninant lcg. Clin. Biomcch, 22, pp.674-680. Vcrhcijcn. R., 2010. Handbuch furfussbnllkondition. ln: G. Sporis, t. Jukic, L. Milanovicand V. Vucctic, cds. 2010. Reliability and factoria\ validily of agility tcsl~ for soro:r players. J Strcngth Cond R~"'' 24(3), pp.6i'9-ó!l6. Viru, A. and Viru, M., 2001. Biochcmical Moniloring ofSporW Training. Charnpaign, !L: Human Kinctks. Vosscn, J.F., Krnmcr, /.F., Ourkc, D.G. and Vo=n, D.P., 2000. Cornparison of dynamic push·up training and plyomctric push-up training on upper-body powcr and ~trcngth.Joumal ofStrcnsth nnd Conditioning Rl-scarch, 14, pp.2-!S-253. Walshc, A.D., Wllson, G.J. and Murphy, A.J., 1996. Thc validity and rcliabi!ity of a tcst oi lowcr body mu"culotcndinous sliffnecoS. Eur J App! Physiot 73, pp.332-339. Wr,1zi;. C.B., Maxwell, N.S. and Doust,).H. 2000. Evaluation ofthcrcfobility and validity oi asocccr-spcdfic fiel d tcst oi rcpcalcd ~print i!bílity. Eur J Appl Phyr.iol, 83, pp.77·83. HEART RATEAND GPS MONITORING IN SOCCER Werner Helsen, Jan Van Wincke/, Kenny McMillan, Jean-Pierre Meert, Andre Aubert, Pim Koo/wijk, Peter Catteeuw, Arne Jaspers, David Tenney 9.1 INTRODUCTION Heart rate (HR) refers to the number of heartbeats in a set unit of time and is usually expressed as beats per minute (bpm). HR increases ar decreases in response to the demands of the body in arder to balance the requirement and delivery of oxygen. HR is modulated through the autonomic nervous system and the interaction of sympathetic and parasympathetic outflow. Sympathetic stimulation increases HR, while parasympathetic stimulation decreases it. Over the last two decades, HR monitors have been widely used in soccer. Using HR measurement as an indirect marker of 0 consumption has become a valuable, easy-to-use and relatively inex2 pensive tool for measuring the internai training load imposed on soccer players. Validity and reliability have been shown to be good for HR monitors when compareci to ECG measurements for measurement of both HR and heart rate variability (HRV) (Achten and jeukendrup, 2003; Kingsley et ai., 2005). Recently, technical development has focused on real-time monitoring instead of the post-exercise evaluation of recorded data (Schõnfelder et al., 9.2 2011). USE OF HEART RATE AS AN INDIRECT MEASURE FOR OXYGEN CONSUMPTION Physical activity may be best assessed by measuring the oxygen uptake (VO) during exercise. However, this is not very practical to achieve on a soccer field. Research has shown a linear correlation to exist between oxygen uptake and HR. The load resulting from physical activity can therefore be measured by using the HR as an indirect measure of oxygen consumption This comparison is represented in the Swain formula (Swain et al., %HRmax = 1994): 0.64 X% vo2mnx + 37 Example: A player has a maximal oxygen uptake (V02ma.) of 55 ml/min/kg. 60% of V02rnax' so the calculation is 0.64 X (0.6 X 55) + 37 ~ 58% of HRm.,,· For example, if the HRrna• is 200 bpm, the player needs to train at 116 bpm. The coach wants to train at 1149 150 1 FITNESS IN SOCCER Heart rate and GPS monitoring in soccer 9.3 RESTING HEART RATE (HRr) Resting heart rate (HRr) in adults is 60-80 bpm on average, but in elite soccer players, it can vary between 40 and 70 bpm. According to the French newspaper !'equipe, professional cyclist Miguel Indurain had a HRr of 28 bpm. HRr is modulated by the autonomic nervous system, by the parasympathetic branch in particular. The nervous system ensures a controlled, consistently low HR. One of the most pronounced cardiovascular adaptations to endurance training is a lower HRr. This occurs through an increase in parasympathetic or vagal tone (Smith, 1987). A decrease in HR is not only the result of increased sensitivity of the parasympathetic nervous system but also a consequence of greater plasma volume and higher stroke volume. An increase in HRr has been suggested as a way of detecting fatigue and monitoring overtraining (Budgett, 1998). Bosquet et al. (2008) suggested in their review that an increase in HRr may be used as a valid sign of short-term, but not long-term, fatigue. Although nocturnal HRV, rather than HRr, values could be better indicators of cumulated physical fatigue (Pichot et al., 2000), this requires monitoring HR during sleep, which may prove uncomfortable and impractical for athletes in the long term (Robson-Ansley et ai., 2009). FITNESS IN SOCCER Heart rate and GPS monitoring in soccer removal (outflux), resulting in a constant lactate concentration (Moxnes and Hausken, 2009). At exercise intensities above a steady state, a rise in the concentration can be attributed to either an increase in the rate of lacta te production ora decrease in the rate of lactate remova! (Moxnes et al., 2012). The lactate concentration in the blood [La-]b is measured in millimoles per liter of blood, which is abbreviated to mmol/L. 9.5.2 Aerobic threshold The aerobic threshold is sometimes defined as the exercise intensity at which [La-]b reaches an arbitrary concentration of 2 mmol/L. This occurs approximately at a HR of 20-40 bpm less than the anaerobic threshold and around 60-70% of HRrnílx· During this phase, the requirement and supply of oxygen is balanced. Steady-state physical activity is approximately between 2 and 4 mmol/L. Blood lactate [La-], 7 High intensity 6 9.4 MAXIMUM HEART RATE (HRm,,) 5 HRrn"" is determined by genetic factors, and it decreases gradually from the age of 20 in untrained people, with it decreasing slower in well-trained individuais. HRrnnx can be measured by a maximal incremental exercise test. It can be also estimated using various methods (Tanaka, 1991; Bruce, 1974; Londeree, 1982). A brief review of various HRrnnx prediction formulas revealed that the majority of age-based prediction equations have large prediction errors (> 10 bpm) (Robergs and Landwehi;. 2002). HRrnnx can also be estimated on the basis of a simple test, albeit for well-trained soccer players only. Warm up for 10-15 minutes followed by 3-4 minutes running at a tempo of 75-80% HRrnox and finally 30-45 seconds of maximum physical load (maximal sprint). HRrnnx is then measured immediately after this sprint. 4 3 2 :-·-·-·-·-·-. 1 -·- ·-·-·-·-·-·-· Low intensity o Time Fig. 9. 1: Blood lactate accumufation for different intensities 9.5 LACTATE THRESHOLD 9.5.1 Lactate Blood lactate concentration ([La-Jb) is the result of the production and removal of lactate. Lactate is formed continuously, under both aerobic and anaerobic conditions, as a result of substrate supply and equilibrium dynamics (Brooks, 1998). When the rate of ATP production by oxidative pathways is insufficient to respond to the demands of physical activity, high rates of glycolytic (from blood glucose) or glycogenolytic (from muscle glycogen) ATP production are essential to prolong physical activity. The end product of glycolysis is pyruvate, which can be reduced to lactate or oxidized to H 20 or C02• During increasing exercise intensities, the muscles produce more lactate, which is subsequently released into the blood plasma. [La-]b is the result of the production of lactate from working muscles and tissues, and the remova! of lactate in the muscles, liver, renal cortex and heart (Brooks, 2007). During steady-state physical activity, lactate production (influx) equals lactate During low-intensity exercise, lactate is processed or re-used in the form of pyruvate in the less active muscles. As the intensity of the exercise increases, lactate production exceeds lactate remova!. Consequently, lactate starts to accumulate in the muscles. 9.5.3 Lactate threshold The lacta te threshold (LT), the onset of blood lactate accumulation (OBLA), anaerobic threshold (AT) or lactate inflection point (LIP) is the exercise intensity at which lactate starts to exponentially accumulate in the blood. You will also sometimes encounter the term maximal lactate steady state (MLSS), which is defined as the highest exercise intensity where there is a balance between the rate oflactate appearance in the blood and its rate of removal Gones and Doust, 1998; Denadai, 2005). Some studies postulated that the MLSS corresponds to a mean concentration of 4 mmol/L (Heck et ai., 1985, Poole et al., 1988). However, individual variability in this concentration has been observed (Steggman et al., 1981). Different indices FACULDADF OE DESPORTO DA UNIVERSIDADE D P l l 5l 152 1 f ITN ESS 1N SOCCER FITNESS IN SOCCER 1 Heart rate and GPS monitoring in soccer Heart rate and GPS monitoring in soccer related to blood Iactate response to exercise are some of the most widely used parameters for exercise prescription in soccer. Helgerud et ai. (2007) demonstrated that high-intensity aerobic training increased LT in soccer players. ln addition, Coyle (1995) suggested that the prescription of appropriate exercise intensity is more accurate when the blood lactate response to exercise is used. Blood lactate 9.6 RELATING THE LACTATE CURVE TO THE HEART RATE Training zones are designed in modem TRIMP calculations based on [La-]b, oxygen uptake, and HR data. We can demonstrate this using the case discussed below (Fig. 9.4). In this graph, the initial [La-]b levei is 2 mmol/L. The lactate level decreases in this first phase due to the muscles working and lactate being actively processed. When intensity starts to increase, lactate starts to accumulate. [La-Jb ./ Aerobic threshold: - [La-]b: 2.5 mmol/L -HR: 125bpm -load: 12.1 km/h 7 6 s 4 ./ Lactate threshold: - [La-Jb: 4.3 mmol/L -HR: 154 bpm -load: 14.2 km/h Lactate threshold 3 2 1 250 10 o 9 Time 200 r-~~~~~~~~~~~-zS;:-~,. Fig. 9.2: Theoretica/ presentation of lactate accumulation in the musc/e ÊCl. Above the LT, lactate accumulation increases exponentially and can increase to 10-15 mrnol/L in soccer players (Reilly and Korkusuz, 2008). Regular high-intensity physical activity results in a certain degree of mental toughness, enabling the athlete to tolerate higher lactate values for longer. "'"' t: "' :e e 7 150 1-~~~~~~~--:,,,.ic:.~-,,.L.:'._~~~~s ~ . 5 ~ 100 1--~~~~,,..e-::_~~~--:'13/{-~~~~~~~-f4 . 3 flj 50 . 1 Blood lactate [La-]b o 7 6 1-~~~~~~~~~~~~~~~~~~~~--I· 8 10 12 14 16 18 ""'lh-Heart rnte (bpm) 75 98 127 156 178 197 -::0-B!ood lactate [La-Jb 2,4 1,8 2,4 4 6,5 9,5 o Shift in Jactate curve s Fig. 9.4: Determining HR zones 4 3 This graph shows the results of an incremental exercise test (on a treadmill). The player starts the test at 8 km/h and ends the test ata speed of 18 km/h. The graph represents the lactate values, intensity (in km/h) and HR. The aerobic and lactate threshold can be estimated using this graph. ln this example, the aerobic threshold could be set at 4.3 mmol/L (154 bpm) and the intensity is 14.2 km/h. 2 1 o Time Fig. 9.3: Shift in the lactate curve. Training causes the lactate curve to shift for the sarne intensity. 1 53 154 1 FITNESS IN SOCCER FITNESS IN SOCCER Heart rate and GPS monitoring in soccer Heart rate and GPS monitoring in soccer 9.7 INTERPRETING HR MEASUREMENT There are also other factors that influence HR. Although this complicates the interpretation, knowledge of the factors set out below should enable coaches to correctly analyze training. The following factors can cause a small degree of variability in HR: Altitude: Because the barometric pressure of air is lower at altitude than at sea level, the heart has to work harder to transport the sarne amount of oxygen to the muscles. Quantity of active muscle tissue: The more muscles that are used during physical activity, the higher the HR. Running therefore induces a higher HR than cycling (Millet et a!., 2009). Upper body/lower body: Physical activity using the arms results in a higher HR compareci to isolated physical activity of the legs. Ambient temperature and humidity: Temperature and humidity will affect HR. As the ambient temperature rises or the air gets more humid, HR will gradually increase throughout physical activity, even when maintaining the sarne pace. Humidity reduces the effectiveness of sweating, resulting in increased body temperature and a consequent increase in HR. Psychological stress: Stress affects the cardiovascular system. Psychological stress increases HR. Medication or illness: HR is usually higher in cases of illness, and medication can also influence HR. Eating: After a meal, HR increases to aid with digestion. More blood is directed toward the gastrointestinal tract to process the food. Cardiac drift: I-IR will gradually increase during physical exercise carried out at a constant speed. This phenomenon is referred to as cardiac drift. Age: HRmax decreases as people get older due to the physiological effects of aging. Dehydration and nutrition: Dehydration causes HR to rise as the blood volume decreases and the body runs low on the fluids needed to maintain body temperature. Dehydration can occur in cold as well as hot environrnents. A lack of glycogen also results in the sarne effect. Gender: Women typically have a higher HR than men. Caffeine-found in coffee, teas and some sodas-rnirnics the effect of adrenaline, a natural horrnone in the body that is responsible for elevating HR. Other stimulants, such as cocaine and ephedrine, work in a similar manner. 9.8 EFFECT OF TRAINING ON HEART RATE ANO LACTATEACCUMULATION Take the example of the soccer player we tested in preseason. We saw that his speed at LT was 14.2 km/h. We tested the sarne player again after two months of training (three weeks in-season). Fig. 9.6 and 9.7 show the values obtained. 14 . ' 12 3 10 ~ 8 ro 6 o o 4 ,fi. _,.;; ~ _,' , " ,/ - 2 o - ----- _.,,. ...... -- -1 16 18 1 6,5 9,5 1 4,2 11,5 - -- 8 10 12 14 !~=-Testl 2,4 1,8 2,4 4 1-"- Test 2 2,1 1,7 2 3,4 Fig. 9.6: Effect oftraining on lactate accumulation 250 200 Ê e"-w 150 ~ ~ t: ro w :i: 100 50 o "' 8 10 12 14 16 18 Heart rate =-'di=Test 1 75 98 127 156 178 197 (bpm) -=é=-Test 2 70 84 118 146 165 197 200 180 Fig. 9. 7: Effect of training on HR 170 160 150 140 '------------~ Time Fig. 9.5: Carc/iac drift. Although the soccer p/ayer runs constantly at the same speed, HR slowly increases over time and fluctuations are irregular. This phenomenon is known as carc/iac drift. These two graphs show the progression after tvvo rnonths of training. The effects of training, compareci with the first test, were: • The player runs at the sarne speed (intensity) with a lower HRex. • [La-]b accumulation is lower for the sarne velocity. • Aerobic and lactate threshold have risen. 1 155 156 1 FITNESS IN SOCCER FITNESS IN SOCCER Heart rate and GPS monitoring ín soccer 9.9 AUTONOMIC NERVOUS SYSTEM The autonomic nervous system (ANS), also referred to as the vegetative nervous system, regulates a number of bodily functions, such as respiration, digestion and cardiac function. The ANS works autonomously and is therefore not consciously controlled. The ANS actually consists of tvvo systems, the sympathetic system (the "fight or flight" system) and the parasympathetic system (the "rest and digest" system). The hvo systems complement each other, functioning alternately and in opposite directions and working closely together with the hormonal system. The sympathetic system is the body's gas pedal, as it were, enabling us to perforrn. Adrenaline levels, HR, blood pressure, and respiratory rate increase, and then the body consumes more energy. The parasympathetic system can, in turn, be regarded as the brake. It is responsible for recovery, rest and energy replenishment. ln healthy athletes, the two systems are in balance, with moments of exercise (sympathetic system) alternating with recovery moments (parasympathetic system). Devices like iThlete, BioForce and OmegaWave are designed to measure the response of the ANS. The functioning of this system is measured by way of ECG readings of varying duration via appropriate software. HR readings also give an idea of the sympathetic/parasympathetic balance. 9.9.1 Heart rate variability (HRV) The development of technology in soccer has progressed very quickly over the last decade. These technological aids enable the coach to better evaluate the players' response to a given training load, as well as their fitness and freshness. Heart rate variability (HRV) is one of these means. HRV entails the non-invasive measuring of the R-R intervals between two QRS intervals (heartbeats). These intervals can give the coach an insight into the status of the ANS. 9.9.2 Regulation of the hearl HR is regulated by the sinus node, which is also referred to as the heart's "pacemaker." This is a group of specialized cells located in the right atrium of the heart. The sinus node creates its own stimuli and is under the direct influence of the ANS. ln the body, the regulation of the heart is extensively determined by the balance between the parasympathetic (enhanced vagal tone) and the sympathetic nervous system. At rest, the sinus node produces around 100-120 impulses. However, these impulses are influenced by parasympathetic function, resulting in HR falling to around 55-70 bpm when resting. At rest, the body is almost entirely under the influence of the parasympathetic nervous system, with the sympathetic nervous system taking over when physical activity increases. What is remarkable in this regard is that the time interval behveen hvo heartbeats is very irregular (HRV) when resting, while the time interval during physical activity is more regular. 9.9.3 The autonomic nervous system as a regulator for exertion and recovery HRV, a marker of parasympathetic activity, is an accepted term to describe variations in both instantaneous HR and RR-interval (Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology). Heart rate and GPS monitoring in soccer Measuring HRV provides an insight into the relationship between the sympathetic and the parasympathetic systems, which is important for, among other things, development, diagnosis, and the prevention of overtraining, as well as for general health. In common practice, HRr is monitored in order to detect overtraining. An increase of a few beats is, however, difficult to interpret because of the influence of numerous factors, such as circadian rhythms and mental stress. Anticipation of physical activity inhibits the activity of the vagus nerve and increases sympathetic activity. The increase in sympathetic activity and the lowering of parasympathetic activity cause the HR to rise. During physical activity, the vagai activity (and associated parasympathetic activity) diminishes and sympathetic activity increases. As players increase their physical fitness, a number of changes occur in the balance between the sympathetic and the parasympathetic nervous systems. First of all, the parasympathetic system continues working for longer, meaning the HR will be lower for a corresponding intensity. However, the influence of the parasympathetic system also affects recovery. Finally, the parasympathetic system ensures that HRV remains high, even at higher intensity. A High HRV is, for this reason, a good value indicator of the preparedness of an athlete. The effects of the parasympathetic system in well-trained athletes are: o The parasympathetic system continues working for longer in well-trained athletes, resulting in an athlete's HR being lower for a similar intensity. o HR will recover more quickly after physical activity because of increased functioning of the parasympathetic system. • HRV remains high during physical activity. An imbalance in the equilibrium between load and load tolerance will shift the ANS towards sympathetic dominance. This dominance can lead to exhaustion of the endocrine system. This depletion will then later lead to an excessive parasympathetic dominance, especially when athletes are given insufficient opportunity for recovery. 9.9.4 Use of heart rate to measure the functioning of the autonomic nervous system To make progress in soccer, periods of appropriate training have to be alternated with periods of recovery. If there is no balance between the two, players quickly become either overtrained or detrained. Both of these scenarios have a negative effect on performance. The functioning of the ANS can be measured indirectly via the heart rate during exercise (HRex), heart rate recovery (HRR) and HRV. In general, a decrease in submaximal HRex, an increase in HRR and increased vagal-related HRV índices are all well-accepted markers of improved aerobic fitness (Lamberts et al., 2009; Buchheit et al. 2012). On the other hand, opposite changes in these HR measures have been demonstrated to be indicators of impaired physical performance (Achten and jeukendrup, 2003; Mujika, 2001; Bosque! et ai., 2008). As previously mentioned, a lower HRex, faster HRR and greater HRV are all linked to improvements in fitness. To measure a player's fitness during the season, it is important that measurements can be carried out easily and inexpensively and do not require too much effort from the players. 1 157 1ss I FITNESS IN SOCCER Heart rate and GPS monitoring in soccer 9.9.4.1 HRex A low submaximal HR for the sarne exercise intensity is one of the most commonly observed adaptations to endurance training {Andrew et al., 1966). ln a study on highly trained young handball players, a two-month high-intensity training intervention induced a 5% decrease in HRex and I0-20~'o increases in HRR and post-exercise HRV (Buchheit etal., 2008). 9.9.4.2 HRV as an indicator of fatigue and recovery Overtraining and extraneous stressors can induce changes in the functioning of the ANS (Lehman, 1993). HRV can be used to measure the balance between sympathetic and parasympathetic activity. Marsland et al. (2007) were some of the first to demonsh·ate the relationship between parasympathetic dominance and lo\ver cytokine levels and reduced inflammation. A larger stroke volume and an increased parasympathetic response have been suggested to induce changes in the HRV observed within 24-48hours after exercise {Buchheit etal., 2009). A relationship clearly exists behveen recovery after exercise and the endocrine and immune responses of the body. Research has shown, for example, that excessively long sympathetic dominance goes hand in hand with muscle injuries, while reduced vagal activity (parasympathetic activity) of the heart is associated with illness and risk of sudden death. Astate of detraining, as well as fatigue, is associated with a lo\vering of HRV. This often manifests itself in illness or symptoms of overload. Low HRV can therefore predict possible illnesses or diseases. HRV can be low prior to an illness, which means it could be a good indicator for detecting high levels of fatigue or exhaustion. What is also striking is that top athletes have fewer fluctuations in their HRV than less-gifted athletes, probably because they are accustomed to dealing with higher training loads. Another interesting finding in a study by Buchheit (2009) was that following CWI (cold-water immersion), the parasympathetic system was reactivated after supramaximal intensity. The researchers suggested that CWI was effective in resetting the ANS. Massage may have a similar effect, and research has indeed shown that HRV and the parasympathetic system improved after massage (Tritton, 1993). 9.9.4.3 Heart rate recovery (HRR) Although both HRV and HRR provide useful information concerning the balance in the ANS, the two have different origins. An increase in the vagal tone, because of the reduction in sympathetic activity, is shown during the first few minutes after physical activity. Because HRV recovery (recovery from high HRV) is caused by the functioning of the vagus nerve and HRR is caused by the discontinuation of sympathetic activity, results can differ betvveen HRR and HRV recovery. Recent research has shown that V0 2max is correlated to HRR but not to HRV. Although both indicate a good fitness level, they have different origins and can differ for this reason. ln an interesting study, Buchheit et al. (2012) monitored changes in physical performance with HR n1easures in young soccer players. They found that substantial improvements in submaximal HRex (but not HRR) are híghly predictive of improvements in maximal aerobic speed. Conversely, changes in HRR were moderately associated with changes in repeated sprint performance. The researchers postulated that the magnitude of the associations observed were too low to accurately FITNESS IN SOCCER 1 159 Heart rate and GPS monitoring in soccer predict a player's trainability. Additionally, baseline values of submaximal exercise HR, HRR and post-exercise HRV measures obtained before the start of preseason moderately correlated with changes in most of the performance variables over the entire season (i.e., cardiorespiratory but also neuromuscular-related performances), which suggests these measures could be of interest for player screening. 9.10 EXAMPLES OF HEART RATE INTERPRETATION Fig. 9.8: The graph above represents four p/ayers performing an aerobic fitness test. The graph above represents four players performing an aerobic fitness test. The black and white lines represent two fast wingers with IO'\V aerobic fitness and V~~\max of less than 60 ml/kg/ min. The light gray line represents a midfield player \VIth a V02 max of 67 ml/kg/min and excellent aerobic fitness. The dark gray line is an experienced midfield player who has already played at the top level for several years. He has a V0 2rnax of 63 ml/kg/min. ln the first round (\varm up), all players run together at the sarne speed. The "black" and "white" players have higher relative heart rates (as a percentage of HRmnJ than the "dark gray" and "light gray" players. This could possibly be dueto a higher HR at lactate threshold. The fact that the HR of both the black and white players increase \vhile the heart rates of the light gray and dark gray players stay relatively stable could indicate that those players have a weaker fitness. This is confirmed by their HRR, which is slower than those of the light gray and dark gray players. The aerobic fitness test starts after five minutes of recovery. The aim of the test is to finish the lap as fast as possible (maximal test). The light gray player is the fírst to finish the test, \Vhile the black and white players finish together and the dark gray player comes in last. Without HR figures, it could be concluded that the dark gray player is notas fit. However, it is clear that this player did not perform a maximal test. His HR does not rise above 90%. The light gray player has also run a submaximal test. Ht~ aerobic endurance is, however, better than that of the dark gray player, \Vhich is why he covers the distance faster. The black and white players both performed a 160 FITNESS IN SOCCER Heart rate and GPS monitoring ín soccer 1161 1 FITN ESS 1N SOCCER Heart rate and GPS monitoring in soccer maximal test. Their time, however, is less than that of the light gray player because of their lower leveis of fitness. It is noticeable that increasing fatigue also causes the HR to rise as the distance covered increases. The interpretation of the recovery is also interesting. The light gray player, with a high V0 2 max anda high level of aerobic endurance, recovers substantially quicker than the other players. The recovery of the two fast wingers (white and black lines) is slower, and after 7-8 minutes, their HRs have sti11 not fallen below 60% of their maximum HRs. '' ' HRM!lX R11COVfliyOO" HBLoa:I 182bpm -20bpm 169 bpm " " ·!!3bpm Fig. 9.10: Training session with a 15-minute warm up, ending with a sprint exercise. A passing exercise is then done for 15'. Fina/ly six games of 4v4 + K are played for 5' with 2' rest. "' 'i Fig. 9.9: Example of a submaximal Yo-Yo /SRT test for a Dutch international p/ayer. The player was tested at the beginning of the season and again after a few weeks in preseason (Figure 9.9). The player's HR is distinctly lower for the sarne intensity (HRex}. This demonstrates an increased physical fitness and increased parasympathetic dominance. This results in a reduced TRIMPavg as an indicator of lower mean HRex. Recovery after completion of the submaximal test is also quicker after a few weeks of training. This confirms the improvement in fitness. The white player is a central defender with considerable experience (31 years old) and average fitness. The gray player (24 years of age) is a (fast) striker with a VO 2m~x of 56 ml/kg/min and low aerobic fitness. The black player is a relatively young (23 years of age) midfielder with a lot of potential. He trains hard and has a high VO 2mnx of 65ml /kg I min. What is immediately striking in the graphs is the high HR of the gray player. He reaches a higher HRmnx than in the laboratory tests conducted before the start of preseason. This is not uncommon. Also striking are the lower HR values of the white player. His interna! training load is lower compared to the other hvo players. This could mean that his (tactical) position in the SSGs was not demanding enough, or he was possibly playing the SSGs submaximally. This is seen more often in older professional players, \vho avoid exerting themselves maximally in the week so as to be fresh at the start of the next match. The black line represents a player who commits himself fully and recovers very well during the breaks. However, the SSGs are less demanding (a lower internai training load) for him than for the gray player. When calculating the training load of this session for the three players, the white player will have the lowest load, the gray player will have the highest training load, \Vhile the black player will have a lower training load than the gray player because of his high aerobic fitness. It is therefore possible to give the white player an additional load (exercise) after the session because of the submaximal training. The black player can also be prescribed an additional exercise because the external load was too low for his fitness levei. 9.11 GPS MONITORING Global Positioning Systems (GPS) are now more widely utilized by coaches as a means of quantifying the physical workload of players, so they can optimize the measurement of training sessions within the athlete monitoring system. GPS can no\v be used to "individualize" training loads within the sarne team. With the addition of RPE and/or HR readings (Impellizzeri, 2005}, this GPS data can be used to better quantify the individual load (mechanical load), but it can also be compared to the individual response to that load (internai load). Such information derived FITNESS IN SOCCER Heart rate and GPS monitoring in soccer lGZ 1 FITNESS IN SOCCER Heart rate and GPS monitoring in soccer from GPS also allows coaches to view the breakdown of different exercises in arder to optimize a periodized plan and prevent overtraining (and undertraining). Playerload GPS technology and its associated software are now able to provide a coach or sports scientist \Vith a myriad of metrics and variables. Currently, companies like Catapult and GPSports have also integrated accelerometers into their GPS units, with the aim of increasing the validity and reliability of the data acquired from their technologies. The last ten years have seen major advancements from the less accurate 1 Hz and 5 Hz units to the increased sampling rates now provided by the newer 10 Hz and 15 Hz systems. 9.11.1 Reliability and Validity ln the past few years, research has focused on assessing the reliability and validity of GPS monitoring (Buchheit, 2013). Most research has found that the newer 10 Hz units with upgraded firmvvare and increased sampling rates have further improved accuracy and inter-unit reliability (Johnson et al., 2013). While it could be argued that older 1 Hz and 5 H~ GPS models were valid for longer distances, total distance, and slower speeds (although not changes of directions) (Jennings et al., 2010), the latest GPS hardware (10 Hz) has been shown to be six times more accurate at measuring instantaneous velocity than the previous 5 Hz models (Varley et al., 2011). 9.11.2 Traditional GPS Metrics As the current GPS technology advances, sports scientists also advance the types of metrics that are used to quantify performance. Currently, when looking at the current research Oohnston, 2013), the performance metrics examined are: Fig. 9.11: P/ayer Load gives an indicaüon of an athlete's total workload. lt includes distances and accelerations/decelerations, as well as changes of direclion. There is a clear difference between the total /oad in training weeks with one game (W17, W19 (for A-team p/ayers) and W22), two games (W18 and W20) orno game at ali due to the intemational ca/endar (W21 ). ,. D!st<mce HIR {>20km/h) Total distance covered Meters / min • High-speed distance covered 0 Player Load (accelerometry-based) 0 Very-high-speed running • RHIE (repeat high-intensity efforts) 0 RSE (repeat sprint efforts) 0 Time or distance spent \vithin different velocity bands 0 0 Aughey et al. (2013) have also used GPS monitoring during friendly matches and compareci the physical data from these matches against other football codes, such as rugby and Australian Rules Football, to create a unique perspective into the exact physiological \VOrkload required of a soccer player relative to other sports. This research seems to support the increased importance of RHIE (repeated high-intensity effort) rather than RSE (repeated speed effort) by including accelerations, decelerations and collisions into the equation as high-intensity activities. Fig. 9. 12: ln weeks with a midweek game, recovery has priority, and little orno Hl-running is included in training sessions. W21 was a non-game week dueto the international calendar, giving the opportunity for a high Hl-running training load. 1 16 3 164 1 FITNESS IN SOCCER FITNESS IN SOCCER Heart rate and GPS monitoring in soccer Heart rate and GPS monitoring in soccer 9.11.3 Metabolic Power Playcrlo::id =I =I ;;rol '"""! _ _ ' ·~I '~" 1-., • I -....,.,,.,.,,""'"""' <v _ o~ ' <v ,.~ r ~-\."+~;"'~:~'º i w:::"'""'~:!'" w,•;:,,,""'f~:' w,~,~V>.' ......'0' ' w:;;.~uln'",':}," 1w';;';:'"""";~':": '~-~~'f'c!,.,,,..,.t":"!'. ?'! '"' -,- .,, 10Õ .,,- ' 4l0 =·'°·~~·-~~~·~cc·~'~~~~·~~~~"·--.-~=- ~.:~--~~-~~=~~ :- -,- ---,---- -----, i -·,,, - @ - 1'1 •to ON ----~-~,-- A recent development in the area of training load quantification with GPS technology has been the work into metabolic power carried out by Osgnach (2010) and di Prampero (2008). The metabolic power approach to training load quantification begins to view the physiological demand of training sessions from a perspective of power output and energetic cost. It is measured in W /kg rather than the traditional work performed at different velocities. When comparing different exercises measured with "total power" metrics and "total speed" metrics, Gaudino et al. (2013) found that coaches and sports scientists underestimated training load when assessing the load just from a velocity perspective. As a result, many GPS companies are now trying to implement this "metabolic power" metric into their software for future clients. Some researchers seem to believe that, in the future, metabolic power metrics may provide a more valid measurement of the true loads required in drills such as small-sided game play, such as 3v3 and 5v5. The other advantage of the metabolic power metric is that it seems to be more sensitive to positional differences within such games. According to Gaudino and colleagues, the workloads of central defenders in particular tend to be underestimated with the use of traditional GPS and velocity-based metrics. Distante HlR {>20km/h) SUMMARY It is of great importance to measure the training load of soccer training. Internai load can be rneasured through the use of HR monitors. Resting HR, the HRex, HRR, and HRV are tools that can be used to help track the fitness status of the players. GPS technology can be used to measure the external, mechanical load of training sessions. Information gleaned frorn GPS <levices also allows coaches to rneasure rnetrics, such as nurnber of accelerations and high-intensity distance covered, in order to optimize a periodized plan to prevent over- and undertraining. Training load rnonitoring is discussed in more detail in the following chapter. Fig. 9.13 & 9.14: A comparison between two A-team players: a winger (VA) anda central defender (CA). A cfear difference is seen in externai foad between lhe playing positions, with lhe most obvious difference in distances covered at high speed (Hf running). This is one ofthe main reasons for the difference in P/ayer Load between both p/ayers. These differences in Z4 and HI running (and consequently P/ayer Load) are mainly dueto position-specific games like 11v11, 9v9, 7v7. These differences are seen /ess in SSGs (5v5, 4v4, 3s3) and other dril/s fike passing and warming up. l lGS 1661 FITNESS IN SOCCER Training load monitoring in soccer FITNESS IN SOCCER Heart rate and GPS monitoring in soccer 1 REf ERENCES Achlen,J. and jcukcndrup, A.E., 2003. Hcarl rate monitorini;: applic.itions and limilíltiono.Sports Medicine, 33(7), pp-517-538. Andrew, G.M., Gu~man, C.A. and Bcckfokc, M.R., 1966. Effoct of alhletk training on cxcn:ioc cardfoc output. J ApplPhysio!, 21, pp.603-600. Bosque!, L, Mcrbri, S., Arvisai~, D. and Aubcrt, A.E., 20!IB. ls hcart rate a convenicnt too! to monitor ovcr-rcnching? AsyslcmMic rcvicw of lhe litcraturc. Br J Sports Mcd, ·12, pp.709-71-1. Brooks, G.A., 1998. Mammalian fucl utili«.1tion during "u~taincd cxcrcisc. 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Comparison of Polnr lllOs and an nmbulntory ECG 5yslcm for RR intcrval mc,,urumcnt during progreesivc cxcrcisc. lnlcmalionnl Joumal ofSports Medicine, 26(1), pp.39--~l. L1mbcr!5, R.P. and l.:imberL M.I., 2009. Day·to·day vuriation in hcnrt rale at difforunt leveis of sub maximal cxcrlion: implications for monitoring trainlng. J Stnmglh Cond Rcs, 23, pp.100:;-1010. Lchmnnn, M., Fosler, C. and Kcu~). 1993. Overlrainingand endumnce nthlctes: a brief rcvicw. Mcd SciSports Excrc, 25(7), pp.S5·1-(;i2. Londc=, D.R. ;md Moeschbcr&cr, M.L., 1932. Effcct of age nnd olhcr foctors on maximal hcart rate. Res Quarter Exen: Sport, 53(·1), pp.297-30-1. Marolnnd, A.L., Giannros, P.J., Prathcr, A.A., jcnningo, j.R., Ncumnnn, S.A. nnd Manuck, S.ll., 2007. Stimulutcd production of pro-inflammntory cytokines covaries invc,.,,dy wilh hcnrt rale varinbility. Psychosom Mcd., 69, pp.m9-716. Millct, G.P., Vlcck, V.E. nnd BentlC)\ D.j., 2009. Ph)"'iologic.il difforenres bctwcm cydinB nnd running: lc=ns from trialhlcles. Sports Mcd., 39(3), pp.179-206. Moxncs, J.F. and Hauskcn, K., 2009. A mathcmnlica! modcl for thc training impulse and loctnlc inílux nnd outfiux during excrdsc. lnt J Mod Phys C, 20(1), pp.J.17-177. Moxn<>r.. J.F., H~uskcn, K. and Sandbakk, 0., 2012. On thc kinctic; of anacrobic powcr. Thcorutical Diology and Medical Modclling. 9(29). Mujib, !. and Padifü, S., 2001. Cardio~piralory and mctabolic ch11roctcristic; of detr11ining ín humans. Mcd Sei Sporls Excrc, 33, pp.413--121. OoBnach, C., !'o5cr, S., llcmardini, R., Rinaldo, R. and di Pr11mpcro, P.E., 2010. Enorgy coot nnd mct11bolic powcr ln elite srn:""r: a new m11tch 11n11lysis11pproach. Mcd Sci Sports &crc, 42, pp.170-178. Picho~ V., Rochc, F. and G:tSpoz, J.M., 2000. Rc!ation bctwcm hc1lrt ;ate variability and training load in middl,,..distunre runneru. Med Sci Sport; Excrc, 32(10). pp.01729-36. Poole, D.C., Ward, S.1\., Gardncr, G.W. and Whipp, D./., 1988. A mctnbolic and rcspir11lory profile of thc Upp<.'r Jimit for prolonged excrdsc in man. fagonomics,31, pp.1265-12i9. Reill}~ T. nnd Korkusuz, F., 2003. Sciencc and Footba!I: Thc Proc...>Cdings of thc Sixth World Congf<!ss on Scicncc and Football: v.6. London: Tdylor Fr«ncis. Robe'!>", R.A. and Landwchr, R., 2002. The Surprising Hislory of lhe "Hrmax~22.0·Agc" Equation.Joumal of Excrcioe Phyoiology, 5(2), pp.1-10. Robson-Anslcy, P.J., Glceson, M. nnd Ansley, L., 2009. Fatigue managcmcnt in lhe pr<!paration of Olympic athlctes. Jouma! of Sport; Scicnccs., 27(13), pp.1409-1420. Schúnfcldcr, M., Hintcr:;chcr, G., Pctcr, P. and SpltzcnpfeH, P., 2011. Scientlílc Comp.1rison of Diffcr<!nt Online Hem! Rale Monitoring Systcm.•, ln! J Telemcd Appl., vol. 2011, Artide !D 631!148, 6 pages. doi:l0.1155/2011/ 6318-18. Slegmann, H., Kindermann, W. and Schnabcl, A., 1981. L1ctatc kinctic; and individual anacroblc thrcshold. !nt. J. Sports Mcd., 2, pp.160-165. Swninct ai., 1994. Targct HR for thc dcvclopmcnt of QI fitncss. Medicine & Scicncc in Sports &. E><en:isc, 26(1), pp.112-116. Tnnnb, H., Monahan, K.G. and Sca!s, D.S., 2001. Agc-predictcd maximal hc.1rt rale revisitcd.J Am Col! Cardiol, 37, pp.153-166. Task Force of thc Europc«n Society of Cardiology and thc North Amcrican Society of Pacing and Elcctrophysiology, 1996. Heart rote vnriability: ~tandards oi mco.suremcnt, physiological inlcrprctation and clinica! use, 93(5), ppJl).B-65. Tritton, B., 1993. M=agc and Mrothcropy. Abbotsford, Vk.:TAFE Publkations. TRAINING LOAD MONITORING IN SOCCER lbrahim AkubatJ Jan Van Winckel 10.1 INTRODUCTION Examining the training process is essential to understanding why we measure training load. By measuring the training load, we are looking for a dose-response relationship with the outcome parameter. The dose, or the training load, is the prescribed exercise, and the response of interest in soccer is the associated fitness gain, fatigue accrued or injury risk. Examining the dose-response relationship in this manner allows us to improve our knowledge of ho\V a player might respond to a particular training dose. We can also become more proactive in future when manipulating the dose, rather than merely reacting to the response. This may help us to produce desirable responses, such as fitness gain, or prevent undesirable responses, such as injury. The dose-response relationship is deemed by the American College of Sports Medicine to be a fundamental principie of training. It has also been suggested (Banister, 1991; Manzi et al., 2009) that a valid measure of training load should show a dose-response relationship with the training outcome. The training outcome is usually measured periodically using an assortment of fitness tests, performance parameters and injury records. So, why is the dose-response relationship so important to soccer coaches? We generally react to a response, whether it be an injury ora fitness test score. Given that we want to avoid both injuries and frequent fitness testing, which may be impractical due to time constraints, understanding the response to a given dose enables us to be proactive in achieving our aims as coaches. Understanding the training process is essential to understanding which measurements of training load will show good dose~response relationships. 1167 lGS I FITNESS IN SOCCER FITNESS IN SOCCER 1 Traíning /oad monitoring in saccer Training load monitoring in soccer 10.2 THE TRAINING PROCESS The training process has been conceptualized quite nicely by Impellizerri and colleagues (Impellizzeri, Rampinini and Marcora, 2005). Figure 10.1 below shows h?w both the prescribed training and the characteristics of the individual (e.g., genehcs, training status, etc.) combine to form the intemal training load. ---------TRAININGPROCF.SS---------...._ Individual characteristics r-- Extemal training load Quality and quantity j. ln this chapter, the methods used to examine both internai and externai loads will be explored and their validity assessed. Furthermore, in a practical or applied environment, certain factors may influence 1vhich methods you can and cannot apply, perhaps because of cost, time or practicality. This will also be summarized for each method. The decision of whether a method is worth the associated cost and time is one for individuais to make based on their available resources, but the decision should also be governed by the validity of each method. This chapter aims to help coaches and practitioners decipher all these details and help them in a soccer-related setting. Organization 10.3 INTERNAL LOAD INTERNAL TRAINING LOAD Physiological Assessmcnt TRAINING OUTCOl\.IE Fig. 10.1: The Training Process (fmpelfizerri et ai., 2005) This is best explained with the example of two men of differing fitness levels running a 10 km race at the sarne pace and both finishing at the sarne time. The fitter man would find this less demanding inte1nally, and an analysis of his heart rate (HR) data would show it to be lower than the other man's. ln a soccer-related setting, this would also mean that players running the sarne distance would only show the sarne response if their personal characteristics were exactly the sarne, but this scenario is highly unlikely. Therefore, as the model shows, it is ultimately the internai training load that acts as the stimulus for training adaptation. Measuring training load is particularly difficult in sports such as soccer, because different exercise designs lead to different physiological and mechanical demands, and there are inter-individual responses to the prescribed exercise (Bangsbo, Mohr and Krustrup, 2006). The measurement of training load is often described as either internai ar externa!. Internai training load monitoring is usually based on HR or the rating of perceived exertion (RPE), and is often calculated with the integration of time, intensity and a weighting factor. lntensity has been measured objectively using HR due to its linear relationship with oxygen consumption (Bot and Hollander, 2000), which is widely regarded as the gold standard for measuring exercise intensity (Thompson., 2010). Consequently, it seems appropriate to use HR as a measure of intensity and internal load. In recent years., the development of automated camera tracking systems., GPS and accelerometers has also brought forward the measurement of externai training loads. These measurements of external load provide us with another tool for measuring the training load of soccer players. 10.3.1 Banister's TRIMP Banister et al. (1975) were among the first to pursue a single value to represent the training load or training impulse (TRIMP). Banister originally proposed a threezone model where exercise was categorized as being of a low, moderate or high intensity, and each of these zones was weighted by 1, 2 or 3 respectively. However, the TRIMP method developed later by Banister (1991) is 'ividely used today, and this is based on HR and a modelled blood lactate response to increasing exercise intensity. Banisters TRIMP takes into consideration the intensity of exercise, 'ivhich is calculated from the heart rate reserve method and the duration of exercise. The mean HR for the training session is weighted according to the relationship between HR and blood lactate observed during incremental exercise, which is then multiplied by the session duration. TRIMP is calculated using the following formula: txLIHRxy Where: t = duration (minutes) L.\HR = fractional elevation in HR or HR reserve y = weighting factor The .6..HR is weighted in such a manner that it reflects the intensity of effort and guards against placing disproportionate importance on longer durations of low-intensity exercise when compared with high-intensity exercise. The multiplying factor (y) weights the L.\HR according to the classically described increase in blood lactate in trained male and female subjects. Banister used the TRIMP to model endurance performance when he used it to measure training load, and from this he modelled the dose-response relationships with fitness and fatigue. Banister theorized that each training bout produced both a fatigue and a fitness impulse, \Vith fatigue decaying three times faster than fitness, providing training adaptation and enhancing performance. Performance at any given point is a result of the fitness leve! minus the accrued fatigue. Morton et al. (1990) modelled the endurance performance of two athletes using Banister's TRIMP, and the results gave credence to Banister's TRIMP for endurance events. l69 º 17 FITNESS IN SOCCER FITNESS IN SOCCER 1 Training load monitoring in soccer Training load monitoring in soccer The modelling conducted to date has focused on endi.trance athletes with long training schedules. These athletes may need to optimize performance for competition periods ranging from a single day (e.g., a marathon) to a few weeks (e.g., a cycling tour). The modelling of performance in endurance sports (Morton, 1990) somewhat validated Banister's TRIMP, but the modelling process has been subject to modifications (Busso, 2003) to improve predictions. There are two major limitations when using Banister's TRIMP in intermittent team sports like soccer. Firstly, the use of mean HR may not reflect the fluctuations in HR that occur during intermittent exercise. The mean exercise intensity in soccer matches has been widely reported to be around the anaerobic threshold at 85% of HRm"x (Stolen et ai., 2005), but it has also been reported to peak at close to HRm"x (Ascensao et al., 2008). Secondly, the use of generic equations for males and females implies that gender is the only differing factor in athletes, and this doesn't take into consideration the individual differences that affect training load, such as those implied by the model of Impellizzeri et al. (2005). Associated Costs: HR rnonitors. Practicalities: Easy to calcula te once correct data has been identified and dorvnloaded, and tlie formula is the sarne for each player. Software can also perfonn thís calculation. The availability of 1natch data 1nay be a proble111 at se11ior leveis, because HR 1nonitors may not be tvorn. It is, 1wivever, useful at all other levels. 10.3.2 Edwards' TRIMP Edwards (1993) proposed a zone-based method for the calculation of training load. The time spent in five predefined arbitrary zones is multiplied by arbitrary coefficients to quantify training load. The proposed zones are based on HRm"x with 10% zone ranges, and the corresponding coefficients can be seen in Table 10.1. HR Zone {o/o HRmo.l Weighting Factor 50-60% 1 60-70% 2 70-80% 3 80-90% 4 90-100% 5 Tabfe 10.1: HR weightings proposed by Edwards (1993). This method gained popularity as the default setting on a popular HR system. However, the coefficients lack any physiological underpinning, and the zone limits remain predefined and lack metabolic or physiological performance thresholds. These zones and weightings imply that the training adaptation in zone 5 is five times greater than in zone 1, but no study to date has proven this to be the case. The weightings used by Edwards (1993) are not validated through a relationship with a known physiological response. Throughout this chapter, we will encounter a num- ber of methods that have tried to validate themselves through their relationship to this method. This has been dane on the basis that HR is a valid measure of intensity (Bot and Hollander, 2000), but where intensity is only one term in the equation for training load (with the others being time anda weighting factor). On the other hand, there is evidence to support the use of generic high-intensity thresholds. Castagna et al. (2011) showed a dose-response relationship between the time spent above 90% HRm~x and changes in fitness. Although useful, using such approaches exclusively risks ignoring the training load accrued from training below the threshold and the remaining intensity continuum. This could mean that vital load information is being missed, and this could make the difference between fitness and injury. Costs: HR 1nonitors. Practicalities: Usually rveightings and zones can be set in the software provided rvith the hardware, so calculation is relatively easy. Availability of 1natch data is again a proble111 at senior leveis. 10.3.3 Lucia's TRIMP Lucia et al. (2003) based their measure of training load around the first and second ventilatory thresholds (VTl & VT2). The rnethod provides three zones: low (below VTl), rnoderate (between VTl and VT2) and high (above VT2). Each zone is given a coefficient of 1, 2 and 3, respectively. The time spent in each zone is multiplied by the relevant coefficient and sumrnated to provide a TRIMP score. However, like with Edwards (1993), the weightings are not based on any scientific evidence and/ or physiological data. Earlier \Vork by Banister et al. (1975) with swimmers used the sarne weighting coefficients (1, 2 and 3) for low-, moderate- and high-intensity work, but, as previously mentioned, he later changed his approach and based the \Veighting on the blood lacta te response instead. This sort of weighting irnplies that high-intensity exercise is three times as demanding as low-intensity exercise. Lucia et al. (2003) used this method to successfully compare the training load distribution for two different cycling tours, and they reported no significant differences in the calculated training load for the two tours (the Vuelta a Espafia and the Tour de France). Training using this three-zone model in endurance sports has received some attention (Esteve-Lanao et al., 2007; Seiler and Tonnessen, 2009), giving the method credibility because of its use in elite settings. Seiler described polarized training methods, popular with endurance athletes, where around 80% of their training time is spent in zone 1 (<VTl). The metabolic thresholds used to identify the zones have shown to relate well to endurance performance (Amann et al., 2006), but the weightings remain arbitrary. This system appears to be best used by monitoring the time in each zone and the distribution in competition and training. This certainly does not mean that a universal score from the associated coefficients is valid. Furthermore, the weighting of each zone implies that the training adaptation \vould be the sarne regardless of where in the zone an athlete trained. For example, say the threshold for VT2 is identified at 85% of HR . Now, a training session with an intensity of 95% of HRm~~ would be given the s~~e weighting as a training session at 85% of HRm~x' yet it would be weighted differently if the athlete trained at84%. 1 171 in I FITNESS IN SOCCER FITNESS IN SOCCER Training load monitoring in soccer Training Joad monitoring in soccer The shtdy of Denadai et al. (2006) showed how a 5% difference in training intensity (95% velocity at maximum aerobic power (vV0 2mnJ vs. lOO%vV02m") produced different training adaptations. For this reason, the use of any zoning method is questionable. Impellizerri et ai. (2005) did demonstrate that train_ing above and below such thresholds may produce differing training responses in soccer players althouah the threshold was based on an arbitrary lactate value. However, m~nitoringjust high-intensity activity in isolation means that the accrued trainin? Ioad from Iower intensity activity could end up being ignored. To date, no tra1ning study on Lucia's method has been conducted to validate that it demonstrates dose-response relationships in soccer. Costs: HR nionitors, regular testing and analysis. Practicalities: Weiglitings and zones can usually be set in the sofhoare provided zvith the hardzvare, so calculation is relatively easy. The testing and interpretation of data for a 1ohole squad is tinie cons11111i11g and potentially costly. It 1vould need the purchase of gas analysis systen1s/lactate analyzers ar the hiring of tltird parties to do tlze testing. The avai/ability of 1natch data is a proble111 at senior leveis. 10.3.4 Stagno's modified TRIMP (TRIMPmod) Stagno et al. (2007) developed a modified version of Banister's TRIMP in an attempt to quantify training load for field hockey. Rather than using a generic equation to reflect a hypothetical blood lactate profile, these authors directly measured the blood lactate profile of the hockey players. The vveightings used therefore reflected the profile of a typical blood Jactate response curve to increasing exercise ~ntensity for the specific population, the hockey team in this case. Rather than be1ng truly individualízed, their method used the mean blood lactate profile from all of the players to generate the weightings, which provided at least some degree of individualization. They then anchored five HR zones around the lactate threshold (LT, 1.5 mmol/L) and the onset ofblood lactate accumulation (OBLA, 4 mmol/L), with the resulting zone \Veightings being 1.25, 1.71, 2.54, 3.61 and 5.16. The accumulated time in each HR zone \Vas then multiplied by its respective zone weighting to derive an overall TRIMPmod. The research quantified the training load in hockey and established relationships behveen TRIMPmod and various fitness parameters during the course of a season. They found the mean weekly TRIMPmod shared significant relationships with changes in running velocity at OBLA and V0201ax· They also reported significa~t correlations between the time spent in high-intensity activity and the change In VO and the change in vOBLA. The dose-response relationships of this study sug~~-~t that TRIMPmod is a valid method to measure training load. The original TRIMP of Banister (1991) is calculated using the mean HR for a particular exercise session or interval of training. Stagno instead used tin1e accumulated in zones to reflect the differing intensities at which team-sport players work. By con1parison, endurance athletes may \Vork at a particular intensity for longer periods, and this may make the use of a mean HR more suitable and less of an issue for them. However, the modern training regimens of endurance athletes also use high-intensity, interval-type approaches. Stagno didn't compare his method to BaniSter's, and \Ve do not kno\v if there is any significant difference when using the zone method of Stagno rather than the mean HR method used by Banister. The difference has, however, been shown to be significant for a single exercise bout (Akubat, 2009). The zones used by Stagno were based on the HR at LT (defined as 1.5 mmol/L), and OBLA (defined as 4 mmol/L). They used the blood lactate responses at four different speeds from their player sample to create an equation for the weightings (the y value defined by Banister). Zones 2 and 4 were created around the mean HR at LT and OBLA. A zone width of 7% fractional elevation was formed at these points. Zones 1, 3 and 5 were then created around zones 2 and 4. The prerequisite for using this method was that the HR at LT and OBLA for ali players fell within the created zones. However, the use of zones also has the limitation of awarding the sarne weighting to exercise spanning the whole zone. For example, if a zone spanning 70-80% of HRm~x had the sarne weighting, an athlete training at 71 % would get the sarne weighting as another athlete training at 7996. It is difficult to ascertain if this difference would affect physiological adaptation, and there appears to be a Jack of studies examining this fundamental training question. However, with Stagno' s method, the zones are created around the thresholds, so there may well be situations where players exercising in the sarne zone, and thus gaining the sarne weighting, are actually each working above and below a metabolic threshold. Impellizerri et al. (2005) showed this could produce different results. It must be highlighted that although the zones are based on metabolic criteria, they are created with arbitrary values of lactate and are therefore not individualized as with Lucia's method. Another issue with using weighting that is individualized to a team is that it still does not account for individual differences. Figure 10.2 below sho\vs data collected from a squad of professional players from the championship division in England. Note how the regression line from which the weightings are calculated is well below the data points for some players, especially at higher intensities, possibly leading to an underestimation of training load. 14 0,4 0,5 0,6 0,7 ll.Henrt Rate 0,8 0,9 Fig. 10.2: Bfood factate responses for a squad of championship soccer players. 1 173 174 1 FITNESS IN SOCCER Training /oad monitoring in soccer ln sumrnary, the work of Stagno highlighted some of the complexities involved in monitoring the training load in team sports. They lüghlighted the need for specific weightings, although they did not fully individualize these, and their use of zones was an attempt to move beyond the use of mean HR. The highlighted limitations exist, but they still produced significant dose-response relationships, and at the time, this study was a big step in the right direction. A number of teams have used Stagno's "\veightings, but a core point is often missed. These weightings were specific to that particular team, and to apply this approach successfully, you would need to do the sarne testing to calculate specific weightings for your own team. Banister used mean HR, citing that calculating the TRIMP for each reading would be too problematic. However, modem computing can achieve this, so given the highlighted limitations of zones, why not assign each HR reading a weighting and avoid the need for zones? The next method described does exactly that. Costs: HR 111onitors, regular testing and analysis. Practicalitíes: Weightings and zones can usually be set in the software provided zvith the hardrvare, so calculation is relatively easy. Testing and interpretíng the data for a rvlwle squad is ti111e cons1uning and potentially costly. It zvould need tlze purclmse of lacta te analyzers or the híring of a third party to do the testing. The avaílability of 1natch data is a problenz at senior levels. 10.3.5 lndividualized TRIMP (iTRIMP) A group of Italian researchers, led mainly by Vincenzo Manzi, were the first and most prominent researchers of this method. Using this method, the TRIMP weighting is based on an individual's own heart rate and blood lactate response to incremental exercise, as measured during a standard lactate threshold test. Furthermore, as a development on previous methods, Manzi et al. (2009) did not use HR zones or mean HR. The TRlMP scores were calculated for each HR reading and summated to give an overall iTRlMP score. ln comparison to methods employing zones, they had effectively created a zone for each HR reading from resting HR to HRnux· These researchers had effectively individualized the \Veighting to the athlete, going beyond the previous individualization by gender (Banister, 1991) and group (Stagno et aL, 2007). Moreover, the iTRIMP weighting is not arbitrary, as \Vas the case in the methods of Edwards (1993) and Lucia et al. (2003). Consequently, this method overcomes many of the limitations of the previous methods. Manzi et al. (2009) published results using the iTRIMP method. These showed that after an eight-\veek period of training in recreational runners, the mean weekly iTRIMP significantly correlated with changes in velocity at lactate threshold (vLT; r=0.87 and vOBLA; r=0.72). The mean \Veekly iTRIMP also showed significant correlations with changes in 5,000m (r=-0.77) and lO,OOOn1 (r=-0.82) running performance. ln contrast, Manzi reported that Banister's TRIMP failed to show significant relationships \Vith any fitness parameters or performance measures. Since the HRV02 relationship appears to be valid even during intermittent exercise (Esposito et ai., 2004), the iTRIMP method has potential for use wíthin a soccer environment. Two studies were recently published that looked at the iTRlMP in senior and youth soccer players (Akubat et al., 2012; Manzi, et al., 2012). During the preseason of an ltalian Serie Ateam, iTRlMP showed dose-response relationships with changes FITNESS IN SOCCER Training laad monitoring in soccer in VO,m,, (r=0.77), velocity at ventilatory threshold (r=0.78), vOBLA (r=0.64) and Yo-Yo lRl performance (r=0.69). The study conducted in the playing season of a youth team from an English championship club showed a dose-response relationship with changes in vLT(r=0.67) but not with vOBLA. Akubat et al. (2011) also compared the weekly iTRIMP scores to session RPE and Banister' s TRIMP and a modified version of Stagno's TRI:MP (group \veightings but no zones). The results were similar to previous studies that compared these methods to each other. Session RPE related well to Banisters TRIMP, but iTRIMP showed poor relationships with the other measures. This is all great new information, but the versatility of this method is best shown in another study by the sarne Italian group of researchers, this time headed by lellamo et al. (2012). They employed the iTRIMP method to measure training load with cardiac patients. They compared the effects of continuous-aerobic training and interval-aerobic training programs on numerous health and fitness measures. They matched the dose of exercise for each group using the iTRIMP method. There was no significant difference behveen the groups in all the measured variables. The measurements did show changes over the training period (V02peak improved by 22% ), but there was no difference between the groups. This has major implications for practices that could be employed in different sporting situations. ln summary, the iTRIMP research since 2009 has considerably furthered our knowledge of training load monitoring. Costs: HR 111011itors, regular testíng and analysis. Practicalities: Softzvare is now available tlmt allows quick and easy a11alysis of HR and provides iTRIMP scores, but ntanual calculation is ti111e consurning. Testíng and ínterpreting the data for a rvlwle squad is ti1ne consurning. It requires the purchase of lactate analyzers or tlie lzire of third parties to pe1fonn the testing. The availability of match data is a probletn at senior levels. 10.3.6 Session RPE Training load measured by the session RPE is a subjective way of quantifying the load placed on an athlete. It is calculated by multiplying the session intensity by the duration to provide a measure of load in arbitrary units. The intensity is desCribed as a number (0-10) on the CR-10 Rating of Perceived Exertion (RPE) scale proposed by Borg et al. (1987). Significant relationships between RPE and other measures of intensity like HR (r=0.89) and plasma lactate concentration (r=0.86) have been demonstrated (Gabbett and Domrow, 2007). However, something being a valid measure of "intensity" does not imply it will be a valid measure of "load." Poster et al. (1996) showed that increasing the training load (as measured by Session RPE) tenfold over 12 weeks resulted in a 109~ performance improvement in runners and cyclists. However, the study also showed poor dose-response relationships between session RPE and changes in performance (r=0.29). Gabbett and Domrow (2007) also reported a poor association betvveen session RPE and changes in skinfold thickness, speed, and V02 m~x during any of the training phases they monitored. In many sports, the usefulness of session RPE stems from its ease of use when compared to the technical nature of using HR monitors. Possible issues include loss of data and player compliance. 1 175 176 1 FITNESS IN SOCCER FITNESS IN SOCCER 1 Training load monitoring in soccer Training load monitoring in soccer The study of Impellizerri et al. (2004) compares session RPE to the methods of Banister (1991), Edwards (1993) and Lucia et al. (2003), and the relationships imply the validity of session RPE. Impellizerri et al. (2004) concluded that with only 50% of the variation in session RPE being explained by HR, it cannot be deemed a valid substitute. A similar study was conducted by Alexiou and Coutts (2008) where session RPE was correlated in different types of training sessions for female soccer players, with a significant relationship to HR-based methods reported. Such approaches, where new methods are compareci to older methods to validate their use, are becoming quite common. However, these relationships presented in such studies could justas easily imply that the new method is justas bad as the old one rather than justas good. More recently, Brink et al. (2010) assessed the dose-response relationship of session RPE with performance and recovery. They used session RPE, total quality of recovery (TQR) and performance in young, elite soccer players over a whole season. Daily logs were kept by players and coaches to report the training load after sessions and the TQR before the following session. To assess performance, they used an interval shuttle run test on a monthly basis. They applied multi-levei modelling techniques to examine whether session RPE could predict performance and recovery outcomes. They reported that the number of training days significantly predicted the performance outcome, as represented by a decrease in the HR during the ISRT. However, the model did not significantly predict performance with session RPE or TQR. Although the simplicity of session RPE cannot be denied, the usefulness of the information it provides is questionable. The studies of Brink et al. (2010), Gabbett and Domrow (2007), and Foster et ai. (1996) show that session RPE doesn't appear to fit dose-response models. Although dose-response relationships tvith fitness or performance appear to be lacking, a recent study looking at the changes in session RPE "\Vithin individuais has shown it may be useful as a predictor of injury. Rogalski et ai. (2013) found that larger weekly or fortnightly session RPE scores and larger week-to-week increases in load were significantly related to injury risk. Session RPE may relate better with injuries rather than performance or fitness responses because one of the main precursors of injury is fatigue. Table 10.2 shows both internai and externai training load measures from tvvo simulated soccer matches (Akubat et al., unpublished) using the modified BEAST protocol (Akubat et ai., 2013). ITRIMP Match 1 2 Mcan 409 304 SD 174 91 Distance 1 2 10810 10604 664 592 Player Load HID sRPE 1 2 1 2 1 2 3336 2868 1301 1257 639 728 718 754 94 145 99 99 p value 0.015 0.171 0.046 0.426 0.010 Cohen's d 0.48 0.21 0.43 0.27 0.60 Effect Slze Smal! Small Small Small Moderate Tab/e 10.2: Load measures from two consecutive matches 48 hours aparl. These matches were separated by 48 hours, and the data for the high-intensity distance covered shows that the externai performance was negatively affected. Players were instructed to run as much as they could, so it could be reasonably assumed that fatigue or a Jack of recovery is the reason for their reduced performance. However, the interesting change is in the iTRIMP and session RPE scores. iTRIMP tvould suggest a reduced interna} load for the second match, whereas session RPE would suggest an increased perception of interna} training load. ln this situation, we are dealing with objective data versus subjective data. A higher session RPE score may be a reflection of the perception of load in an unrecovered state or when fatigued. Therefore, in situations where there is inadequate recovery, an identical or reduced externai load will be perceived as a greater internai load with session RPE. Costs: 111ini11ml. Practicalities: Easy to ad111inister and silnple to calculate. Can be difficult to avoíd one player influencing the scores of another player in a tea1n e11viro11111ent, and this can add to lhe poor reliability and variability that has been reported. Software and s111artphone apps are norv available to nmke tlzis easier. Match data available. 10.4 EXTERNAL LOAD The measurement of externai load in soccer dates back as far as 1952 (Winterbottom, 1952), when hand notation methods were used to estimate the externa} demands of a game through the use of distance. ln more recent history, the use of automated camera systems has brought to the fore the use of distances and breakdowns of the velocities at tvhich these distances are covered. This method has enabled the determination of positional differences (Di Salvo et al., 2007), leveis of play (Mohr, Krustrup, and Bangsbo, 2003), and match-to-match variation (Gregson et ai., 2010). More recently, much of this research has been reexamined using a newer method. The invention and subsequent use of GPS technology has revolutionized the way we track, monitor, and examine both the loads on players and their performances. Whereas semi-automated can1era systems tvere mostly limited to stadiums, GPS technology has the advantages of being usable almost anywhere and providing real-time data. Ironically, the surrounding structures of some stadiums may hinder GPS units from connecting to the satellites they use to calculate their location. The use of these <levices has also bought many challenges, because they are also notv equipped with accelerometers, gyroscopes, and magnetometers, meaning we can accumulate a wealth of data. The invention of these technologies has also led to the emergence of data mining, where everything possible is collected and then examined. On the other hand, some practitioners prefer to use only data that gives them useful information. Again the approach you choose will depend on the resources at your dispasa} and the effectiveness with which you can use the data. Does this ímpact on fitness, performance, wellbeing, and/ or injury risk? ln this section, 1ve will examine what externa! load can tell us about the dose-response relationship and assess the validity of external methods for measuring training load. 177 178 1 FITNESS IN SOCCER Training load monitoring in soccer 10.4.1 Distance As an external measure of training load, any dose-response relationship will be mediated by the individual's characteristics in accordance with figure 10.1 (presented earlier in this chapter). A theoretical comparison of an elite runner and a recreationa1 runner who run SOOOm at the sarne pace exemplifies this. The stress on each runner is determined by their individual fitness states, and even if the distance and pace is identical, the dose and therefore response will be different in each individual. As fitness can also change within individuals, the sarne 5000m at the sarne pace will not always produce the sarne levei of stress. Typically in soccer, we have seen the use of total distance (TD) and high-intensity distance (HID) as measures of externa} load or performance. HID has gained some credibility as a measure of exertion and performance through construct validity when comparing moderate-to-elite-level players (Mohr et al., 2003). It has also been shown to vary greatly from game to game (Gregson et al., 2010). It has been suggested that TD and HID may be valid indicators of load, because soccer players will run as much as possible during matches. Others argue it is stimulus-driven expenditure determined by factors such as state of play, position and tactics, to name but a few (Impellizzeri et al., 2005; Rampinini et al., 2007; Rampinini et ai., 2007). When assessing load using distance data, speed thresholds have also been individualized. 10.4.2 lndividualization oi Speed Thresholds As individuals may possess different leveis of fitness and physical capabilities, comparing variations in the distance data between players may yield comparable statistics on performance. However, the area of interest in this chapter is exercise dose, and generic thresholds for speed will not give comparable exercise dose data. The methods described below have been popular recently in training regimens for soccer. Abt and Lovell (2009) proposed that high-intensity speed thresholds should be individualized based on ventilatory thresholds (VT) in a similar manner to the methods proposed by Lucia et aL (2003), which \Ve discussed earlier. This \vould require a laboratory treadmill test with gas analysis. They found that the median high-intensity threshold, as determined by the velocity at the second VT, (VT2), \Vas 15 km/h (with a range of 14-16 km/h), considerably lower than the defaults of many GPS and camera tracking systems. They found the mean distance run at high intensity, based on the default of 19.8 km/h and the VT2 speed, was 845m and 2258m respectively. This represents an almost three-fold increase in the high intensity exercise dose. A follow-up study (Lovell and Abt, 2013) found that total distance covered in the three different zones proposed by Lucia was 26?1', 57% and 17% for lov.,r-, moderate- and high-intensity zones respectively. They also identified a 41% difference in the high-intensity distance covered between two players of the sarne positional role when zones were individualized, compared to only 5-7% when zones were not individualized. Speeds above a high-intensity threshold of 15 km/h representa large zone because peak speeds have been reported to be well above 25 km/h (Gregson et al., 2005). Therefore, other researchers have proposed the use of maximal aerobic speed (MAS) and maximum sprinting speed (MSS) to generate training zones. Using this method, supramaximal running speeds (speeds >MAS) can be identified (Buchheit FITNESS IN SOCCER Trainíng load monítoring in soccer 1179 et al., 2013). These can then be used for programming, breaking down the high-intensity running zone above VT2 into smaller blocks. When MAS has been used for individualized training regimens, exercise intensities have been prescribed as percentages ofMAS (Baker, 2011). Using the approach where zones are individualized based on physiological thresholds, the intensity becomes rela tive to individuals' fitness levels. Given the framework proposed by Impellizerri et al. (2005), this approach could be considered as an internalized measure of training load with the measurement of externai performance. It would appear that when you are using externa} measurements for monitoring load, these individualizations are essential. Numerous studies have shown the benefit of high-intensity training programs in soccer (Hoff et al., 2002). Castagna et al. (2011) showed how the interna} training load at high intensities shows dose-response relationships, but such relationships with externai performance have yet to be shown. There is, however, likely to be a similar relationship, given that training above VT2 or MAS produces a high HR. It is also worth considering the study of Denedai et al. (2006), which showed marked contrasts in adaptation between groups that trained at 95% and 100% of vV0 2m""· So, the debate about zones and differences remains, because in a zone with a 10% width (e.g., 90-100%), a player exercising at 91% would receive the sarne creditas one exercising at 99%. The approaches somewhat internalize the externai measures of load, but it still remains difficult to equate the distances covered in all zones, regardless of ho\v they are reduced to a single number for exercise dose or training load. There are two major criticisms of the velocity-based measures of load used by GPS companies and researchers to promote other measures. • Movements that don't create vertical displacement are not accounted for. • Activity isn't considered to be high intensity unless speed thresholds are breached, \Vhereas accelerations that do not result in top speed are justas, if not more, energetically demanding (Gaudino et al., 2013a; Gaudino et al., 2013b; Osgnach et ai., 2010). This has led to the development of both accelerometry-derived load and metabolic-power calculations, both of which are now available from some GPS technology suppliers. lBO 1 FITNESS IN SOCCER Training load monitoring in soccer 10.4.3 Accelerometry Accelerometry in soccer has come together with GPS technology, because these units are now available with accelerometers built into them. The accelerometry-derived load has been described as externai load, mechanical load, and center of mass acceleration in all three planes of movement. The algorithms used differ between GPS companies. Research studies have sought to validate accelerometry-derived load by correlating it to some of the internal-load measures mentioned earlier. The Player Load (Catapult) and Body Load (GPSports) are two oi the accelerometry-derived load measures. Player Load appears to relate to session RPE and Edwards' TRIMP (Casamichana et al., 2013), and Body Load doesn't appear to sho\v any relationship with session RPE (Gomez Piri et al., 2012). Unpublished data (Akubat et al., unpublished) suggests that Player Load shows very large correlations with session RPE but only trivial relationships \vith iTRIMP. You could speculate that given iTRIMP has shown dose-response relationships (Akubat et al., 2012; Manzi et al., 2012; Manzi et al., 2009), the lack of any relationship with iTRIMP would bring into question the ability of Player Load to show a dose-response relationship. However, this is merely speculation, and to truly assess the validity of any accelerometry-derived load measure, training studies such as those done previously for other methods are required (Akubat et al., 2012; Manzi et al., 2012; Wallace et al., 2013). 10.4.4 Metabolic Power Accelerations and decelerations are high-intensity and energy-demanding activities, even at low absolute velocities. However, the way high-intensity activity is determined when using velocity thresholds does not always account for this (Gaudino et al., 2013a; Gaudino et al., 2013b). Di Prampero et al. (2005) developed a mathematical approach to quantify the estimated energy cost associated with any instantaneous change in velocity. It was proposed that accelerated running on a flat terrain is considered energetically equivalent to uphill running at constant speed (Minetti et al., 2002). Metabolic power is calculated as the instant energy cost multiplied by the instant velocity. The ability to calculate instant "energy cost" based on known and measured data and the measurement of "instant velocity" using GPS allows this estimate of metabolic power to be calculated. As both velocity and acceleration are used, it is argued this provides a better estimation of high-intensity activity (Gaudino et al., 2013). Gaudinho et al. (2013) showed that when the equivalent high-intensity metabolic-power threshold (a metabolic power of 20W.kg is considered the equivalent of running ata constant speed of 14.4 km/h) is used in the analysis of soccer training, the actual high-intensity activity could be underestimated by as much as 84%. Therefore, the availability of metabolic-power calculations in GPS software has been an interesting addition to the monitoring of load. However, there are also some theoretical limitations that must be considered. Acceleration measurement with GPS units at higher velocities has been shown to display increased error (Akenhead et al., 2013), and there has also been substantial inter-unit variability reported (Buchheit et al., 2013). There are also inter-individual variations in energy cost, because the sarne acceleration velocities may not result in the sarne energy cost when the data is examined closely (Gaudino et al., 2013). Over the next few years, research in this area will hopefully clarify this method's usefulness in the training process, but the underestimation of high-intensity acti- FITNESS IN SOCCER Training load monitoring in soccer vity in the proportions demonstrated has serious implications for training, adaptation periodization, fatigue and ultimately injury prevention. 10.4.5 Match Load as a Measure of Training Load The use of GPS and its associated technologies has allowed the measurement of match-play activities at previously unlmown depths. One of the approaches often used in practice, but not really in research, is that of using percentages of match-based metrics to periodize and optimize training. For example, a player may aim to do two games worth of work (in terms of distance, accelerometry-derived load or metabolic pO\Ver) in a given week. This approach has fundamental flaws. Firstly, to conclude this method works, \ve must first have evidence that a certain amount of match-like activity produces a certain response. Secondly, the variation in match loads between games and positions (Gregson et al., 2010) means it is difficult to make assumptions about a typical match. The question that arises with such an approach is this: Are we trying to make the technology useful using match demands just because it is something we can measure no\v? Or does this method provide an effective measure of training load? Such a method determines the load without considering initial and subsequent fitness levels. Costs: GPS units are very expensive for an entire squad. Practicalities: Player conzpliance issues for zveari11g 1111its in so111e cases, Lots of data, but is it actually usef11l? Once data is collected, analysis by analysts is requíred. The availability of 1natch data is a problem at senior leveis. 10.4.6 Maximizing Performance using Training Load Monitoring The purpose of any player monitoring is to gain information to help understand the response and produce this response when required. Soccer players may face different challenges to those in other sports where competition is infrequent and allows training and taper periods. ln soccer, the ideal scenario for a coach is to have a player able to participate at his maxin1al capability on a number of occasions (this is discussed in a later chapter). In many European leagues, successful teams regularly play two or three times each \Veek. To help maxin1ize or understand a player's performance capability, we can use some of Banister's (1991) theoretical \vork. He theorized that performance at any given point is determined by the fitness levei of the individual less fatigue. Therefore, by monitoring both fitness and fatigue, \.Ve can assess \Vhen maximal performance is possible and when maximal performance \.Vill be hindered. The n1easurement of fatigue could be subjective (through questionnaires and scales) or objectíve (through physiological assessment). Frequent fitness measurement is also difficult in soccer given the high volume of training and matches. Could training load measures be used to help assess fih1ess? A recent study by Akubat et al. (2013) sho\ved ho\.v integrating the internal and external load could produce ratios that relate to fitness measures, or in other \vords, assess the interna} cost of the externally prescribed exercise. This provides a pseudo-measurement of exercise economy / efficiency. Regular assessn1ent of internal:external ratios could give you informatíon on fitness. 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Rc!ationllhips bctwccn trnining load, injul)~ and fitncss in sub-elite collbion sport athlctes. ]ou mal of SporL• Sdcnres, 25, pp.lSOi·l519. Gaudim>, P., laia, F.M., Alberti, G., Hawkins, R.O., Strudwicl:, A.J. and Gregson, W., 2013. Syslcmatk lli.15 bctwccn Running Spccd and Mctabolic Powcr Data in Elite Socccr l'laycr.;: lnflucncc of Dril11}i>C. lnt J Sports Mcd. Gaudino, P., laia, F.M.,AlbertL G., Strudwicl:, A.J., Atkinwn, G. and Grcg 0.on, W., 2013. Monitoring Training in Elite Soc"'r Playcm: Sys· tcmatic Bias bctwccn Running Spced and Mctabolic Powcr Duta. ln! J Sporlr. Mcd, 3·1(11 ), pp.963-968. G"'&"º"• W, Drust, D,, Atkfoe,on, G. and Sul\'o, V., 2010. Mntch·!o-match vnri.1bility of high·oixed activitics in l'remicr l<!a!lue $CXCCr. lntJ Sporl> Mcd, 31(4). Hoff, )., Wioloff, U., Engcn, LC .. Kcmi, O.J. and Hc!gcrud, )., 2002. Socc.>r spedfic aerobic cndurnncc training. British joumal ofSports Medicine, 36(3), pp.218-221. lellamo, F., Manzi, V., Caminiti, G., V.tale, C., C.1stagna, C., Mawaro. 1-.t, Franchinl, A., Rooano, G. and Voltcrmni, M., 2012. Matchcd dof.c inlcrval and rontinuous excrdse training inducc similar cnrdion!spiratol)" and metabolk adapt~tiom in palicnts wilh hcart foilu"'. ln! j Cnrdiol. lmpcllizzcri, F.M., Rampinini, E., Coutts,A.J., Sa>.1i, 1\. and Marrom, S. M., 200·\. U~ofRPE·baocd training loud ln socrer, Medicine and Scien"' in Spor!s and facrdoc, 36(6), pp.1W2·10-17. !mpelhzzcri, F.M., Rílmpinini, E. und 1-.farcorn, S.M., 2005. l'hyoiologica! =essmcnt of nerobic truining ln socccr. joumal of Sporl5 Sei· cnces, 23(6). pp.533-592. Lm·cll, R. and ,\bt, G., 2013. lndividualization of tomc'-motion analysis: a casc'-cohort eirnmplc. lnt J Sporto Physiol Pcrfom>, 8(·1). pp.-156453. 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Minctti, A.E., Moia, C., Roí, GS, Susta, O. and Fcrrclti, G., 2(102 Enorgy co~t of wulklng and runnmg a! extreme uphill ~nd downhill 5lopcs. J Appl Physiol (1935), 93(3), pp.1039-10·16 Mohr, M., Kruotrup, P and Ban5~bo, J, 2W3 )lfotch pcrformnne<: of h1gh·sl.1ndnrd socccr pbycrs with spccial "'l~"'ncc to devclopm~nt of fotigue. j Sports Se~ 2l(i), pp,519·528. Morton, R.H,, 1990. Modeling human powcr and cndurnnN journal oi Mathcmohcnl Biology, 28(1), pp.494>·1. O;gnach, C., Po~•r, S., Tiernardmi, R., Rin)]do, R. and di l'rnmpcro, P.E., 2010. [nergy cosi and mctnbolic powcr in chtQ rnce<:r a ncw moldt analysb npproach. Mcd So Sports E.~cn:, •12(1), pp.170-178 lbmpinini, E., Coufü, A., Cn~t.1gn~, C., Sae.si, R. and Impclhzwn, FM., 200i. Vanation 1n top levei rncrer match performan(I.' Jntcmnl!· onal Joumal ofSporl5 Mcdidnc, 21l(i2), pp.lO!S.102~ R.1mpinini, E., Impdlizzcri, F.M, Ca5tagna, C., Coutts, A). and Wi~lofi, U., 2007. Tcchnical performance dunng "°""'r ma1chco o! lhe !lalian S,,ric A lcnguc: Efícct oi fotigue nnd rompctiti,·c levei. Joumal ofSckncc nnd Medicine inSport. RogulsYJ, D.. Dawson, ll., Hcosman, J. and GnbbclL T, /., 2013. Training nnd gume louds and injury ri5k in elite Au~tralrnn foolb.llkrs.) Sci Med Sport, 16(6), pp.499·503. Scikr, S. and T(mnC"oocn, E., 2009. lntcn•als, thrmholds and long nlow d ir.lance: lhe role of inlcrnity nnd durution in cndurnncc tramm11 Sport~ Sdcnre, 13, pp.32·53. Stílgno, K. M., Thatcher, R, and \',rn Some"'"· K.A., 2007. A modificd TR!MP lo quantiíy lhe in·ocarnn traimng !oad oi toam ~port pl.1ycm Journal oi SportsScicne<:::-, 25(6), pp.629·63-l. W"llacc>, I..K., Slattel)", KM. and Coutt:;, A.J., 2013. A compari~on of mcthndo for quílntlfying training load: "'btion~hips b<twccn moddkd and actual trainini.; respomc&. Eur J Appl Physiol. Winlcrbottom, W., 1952, SocccrCoaching. London: Nald"'tt Pn.-oo To maximize performance, we must understand the internal load for each externai load prescribed for each individual, so comparing players with each other in this respect may not prove fruitful. A player history, or within player comparison, would help in assessing this and help us to move from being reactive to proactive. Although the dose-response relationships we have found have been linear, more may not always be better. Manzi et al. (2009) showed an inverted-U relationship for iTRIMP and heart rate variability (HRV) changes in runners. They found higher training loads beyond a certain point incurred negative changes in HRV, probably because of overtraining. By building a player history, we can therefore assess what the optímum "load" is by comparing peliods of different training loads with the performance response. This is an iterative process that would continue to change. The frequency at which this iteration needs to take place depends on the sensitivity of the load measures to physiological change. Maybe the process becomes less iterative when the load measure is more sensitive to changes in the athlete's physiology, such as in the case of HR, where the load adjusts to changes in physiology. An increase in fitness \vould result in a decreased HR for the sarne externai load, meaning a higher externai load (intensity or volume) is required to match the internai load. SUMMARY Most methods of measuring training Ioad have limitations, so it is important that soccer coaches select the method with the Ieast limitations that fits their club's budget. It is also important to consider the limitations when interpreting training load data, but the right information, gathered and used in the right way, could help improve a coaches decision 1naking when periodizing individual and squad training programs. A good knowledge of training load methods, limitations and monitoring methods can make a positive impact on soccer players in terms of their performance and health. REFERENCES Ab~ G. '"'d Lovcll, R., 2009. TI>e m,e of individuo1lized opccd nnd intcnsity th.,,c.holdn for dct~m>ining the diot;mre nm nt hi!lh-intcm;ity in profo,..:;ionnJ so"cr. journnl ofSporls Scicnreo, 2i(9), pp.S93-S9S. Akubat, !., 2009. A Compnrirnn OI Mcthod.s For C:ih:ulntinn OfThc Trainin!J tmpube. Papcr P"-'fientcd at thc !nlemational oports scicnre and sports medicine confcrenc•>, Newcnstk'-upon·tyne. Akubnt, L, Patcl, E., lbrrdt, S., and Abt, G., 2012. Mc!hods of monitoring lhe lruinin11 nnd mntch load and thcir rdntionr<hip to changcs in fitnc.i:; in professmnal youth oocc~r pluycm.J Sports So. Alcxiou, H., und Coull5, A., 2008. A compurison of mctho<Ll uocd for qu;mtifying interno! t"1inin11 lond in womcn r.ocrer pluycrs. lnlcrnulionul Joum,11 of Sports Phy:iiology and Pcrfom>ancc, 3(3), pp.320.330 Dukcr, O,, 2011. Rcccnt tn!ndfi in high·intcnoity acrobic trnining for fiel d r.por!o. UKSCA(22), pp.3-11. llong~bo, )., Mohr, M. and Kruo1rup, P., 2()(}(,. Phpic«I and mctnbolic dcmands of training nnd matdl·pl.1y ln thc elite football playcr. journal of Spor\5 Scicnre;, 2·1(7), pp.665·!>7·1. Dnni:;tcr, E,W,, 1991, Modcling Elite AthMic Pcrform.1ncc. ln/. D. MucDoug.111, H. A. Wcngcr & H. ). G"'cn (Edo.), Physiological T~.,;ting of EliteAthkteo (pp.403421). Chumpnign, !llinois: Humun Kinetic;. llaniotcr, E.W., C.1lvcrt, T.W., Sava11c, M.V. and \luch, A., 1975. Asyslcm model oi training for athlctic pcrfom>oncc. Au5lralian Journul ofSporto Mcdicim.·, 7, pp,170.176. ll.inbtcr, E.W., C.1rlcr, j.ll. and Zarkndru>, P., 1999. Trnining thcory and tapcr; validation in trfathlon alhlelen. Europcan Joumal of Applicd Phpiology, 79(2), pp.132·191. llorg. G., Ha&;mcn, P. nnd L1111cr.;trom, M., 1987. Pcrcciwd cxcr!ion rdatcd to heart rale and blood factale during am> and leg excrciõc. EuroJX:nn /oumul of Applicd Physiology and Ckruput!onul Physiology, 56(6), pp.679·635. Dot, S,D. and Hollandcr, A.P., 2000. Thc rdaliomhip b<!tween hcart rntc and nxn;en uptake during non·otcady st.1te cxcrcise. Ergonomks, 43(10), pp.1578-1592. Brink, M.S., Nedcrhof, E., Vi~~chcr, C., S<:hmikli, S.I.. and I.emmink, KA., 2010. Monitoring load, n.;:overy, nnd pcrfom>ancc in young elite SO'«'r playcro. )ou mal ofSt"'ngth and Conditionlng Rcse.1rch, 2.\(3), pp.597·603. lluchhcit, M., A! Haddad, H., Simp>on, ll. M., Pafo1~i, O,, Dourdon, P. C., Oi Salvo, V. and Mendoz-Vill,1nucvn, A., 2013. Monitnring Acccleratiom With Gl'S in Footba!l: Time to Slow Down? lnt J Sporl5 Physiol Perfom>. ll 1 --ti l83 184 1 FITNESS IN SOCCER Training /oad monitoring in soccer FITNESS IN SOCCER Training continuum j 11 TRAINING CONTINUUM Jan Van Winckel, Werner Helsen, Jean-Pierre Meert, Kenny McMillan, Paul Bradley 11.1 INTRODUCTION In the preceding chapters, we described and defined various physical abilities, such as speed and endurance, as well as physical pararneters, such as volume and intensity. We also outlined different methods that can be used to calculate training load. In this chapter, we aim to provide an overview of the different effects of training. There is a Jack of clarity regarding the different terms in the existing literature, with the concepts of overtraining, overreaching and overload being used interchangeably. For example, the term "overtraining syndrome" is used regularly in soccer jargon, yet this state rarely occurs in soccer. Declines in performance can also be dueto other life stressors, so the term "underperformance syndrome" is sometimes used (Budgett et al., 2000), Successful training must involve overload, but it must also avoid the combination of excessive overload and inadequate recovery. Athletes can experience short-term performance decrements without severe psychological or other lasting negative symptoms. This Acute Fatigue (AF) or Functional Overreaching (FOR) will eventually lead to an improvement in performance after adequa te recovery. When athletes do not sufficiently respect the balance between loading and unloading, Non-Functional Overreaching (NFOR) can occur. The distinction between NFOR and the Overtraining Syndrome (OTS) is very difficult and depends on the clinicai outcome and exclusion diagnosis (Meeusen et al., 2013). 1ss lSG I FITNESS IN SOCCER FITNESS IN SOCCER Training continuum Training cantinuum Process Outcome Recovery Training (overload) Acute fatigue (AF) Functional overreaching (short-term OR) Non-Functional overreaching (extreme OR) Overtraining syndrome (OTS) Oay(s) Days -weeks Weeks - months Months - .. lncrease Temporary Stagnation decrease Decrease Continued excessive training !oad after a training Several months with stressfu! competition, stressful team environment, excessive load and inadequate performance decrement Performance Example Acute fatigue after a day with two training sessions Overreaching after a preseason training camp campwith inadequate recovery The reduction in aerobic endurance is significantly greater than for other motor abilities, such as strength, power and flexibility. ln a study conducted by Saltin (1968), five people were kept in bed for 20 days. Their V02m" fel! by 25%. This drop can be mainly attributed to a decline in the heart's performance that occurs, in particular, during the first 12 days of detraining. The physiological effects of 2-4 weeks detraining: o vo2mnx: - 5-10% o resting and submaximal exercise HR: + 5-10% o blood volume: -5-10% o stroke volume: - 6-12% o cardiac output: reduced o flexibility (suppleness): reduced o lactate threshold: reduced 0 muscle glycogen stores: - 15-30% o aerobic enzyme activity: reduced recovery Table 11. 1: The different stages that differentiate normal training from OR (functional and nonfunctionaf OR) and the OTS. (Meeusen et ai., 2013) 11.2 DIFFERENT STAGES OF THE TRAINING CONTINUUM 11.2.1 Detraining Undertraining or detraining involves a load thatis insufficient to maintain or stimulate positive adaptation. Many terms-such as tapering, active recovery and unloading-are also used interchangeably in relation to detraining or underh·aining. Set out belo\V is an overview of the most widely used terms: 1. Active recove1y or unloading allows both the training volume and intensity to drop. Active recovery is used to recover from match load or successive heavy training loads. 2. Taper: The highest levei of performance follows on from a period of tapering. Tapering is defined by Mujika et al. (2003) as a progressive, nonlinear reduction of training load over a particular period in arder to reduce psychological and physiological stress and therefore optimize performance. Tapering differs from unloading in the sense that although the volume and frequency decrease, the intensity remains the sarne (80-100%). This process is very individual, but the best results are typically seen after a recovery period of 7-14 days, which is not possible in the calendar of professional soccer. ln soccer, tapering strategies are imposed in every microcycle for the days preceding a match and during the last phase of preseason, just before the start of the season. 3. Detraining: The term "detraining'' is used when a player's performance levei drops. The detraining effect will appear, for example, a few weeks into the off-season, when players' fitness leveis begin falling rapidly. Physiological adaptations lost over a particular period need more time to recover than it takes to detrain them. Fourteen days of detraining is sufficient to induce a significant decrease in vo2mnx' but it takes considerably longer than two weeks to return to the sarne baseline leveis. The mechanisms of physical deconditioning are many, but it seems that hypovolemia (a decrease in volume of blood plasma), decreases in the activity of oxidative enzymes, and lower muscle glycogen stores are the first factors responsible for a decrement in performance (Oliviera et ai., 2008). 11.2.1.1 Effects of training parameters As highlighted above, detraining is a consequence of reduced frequency, intensity and / or volume. An overview of the effects of a reduction in these three factors is set out below: 1. Reduction in frequency: If training is reduced from six sessions to three sessions, while the volume and intensity are maintained, there is no substantial detraining effect. 2. Reduction in intensity: If the training intensity is reduced by 50%, performance will be diminished significantly. 3. Reduction in volume: Even if the total volume is reduced by 50%, the detraining effect can be limited. This shows that a reduction in intensity, in particular, induces a detraining effect. Reference Days of inactivity Percentage Houston, Bentzen, & Larsen, (1979) 15 -4 o/o vo~m>ll Martin etal. (1986) 40 -20 % vo2""', Houmard, Hortobagyl, & Johns (1992) 14 -5%VO ,_, Coyle et ai. (1984) 21 -8 % Cardiac Output Chi et ai. (1983) 21 -64 ºlo activity aerobic enzymes Costlll et ai. (1985) 7 -20 o/o Glycogen store Tabfe 11.2: OveNiew of detraining effects ! 1s1 188 1 FITNESS IN SOCCER Training continuum 11.2.2 Retaining (maintenance) A retaining or maintenance load is used when further positive adaptation and/ or overload are contraindicated, but maintenance of physical capacity is desired. Soccer training for 60-70 minutes at 60-70% intensity is a good example of maintenance training for professional players. Although strategies to maintain stable performance throughout the season are key to a successful season, retaining loads are rarely investigated by scientific research. 11.2.3 Acuie fatigue Overload training disturbs players' homeostasis and results in acute fatigue, followed by an improvement in performance. (Soccer example: two consecutive intensive training sessions). Intensified training is commonly employed by coaches in an attempt to enhance performance. Subsequently, the player may experience acute feelings of fatigue and decreases in performance because of a single intense training session or an intense training period. The resultant acute fatigue can be followed, after an adequate rest period, by a positive adaptation or improvement in performance, and this is the foundation of effective training programs (Meeusen et al., 2013). The sequence of h·aining and the interrelationship between training and recovery are crucial factors in achieving the desired training response. The term overtraining is often use d in soccer. In this book, the term "overtraining" is used as a "verb" to refer to a process of intensified training that possibly results in short-term overreaching (functional OR), extreme overreaching (non-functional OR), or OTS, depending on the appropriate balance between loading and unloading cycles (Halson and jeukendrup, 2004). 11.2.4 Funclional overreaching (FOR) ar shart-term OR When training continues and fatigue accumulates, or when coaches purposely use a short period (e.g., a training camp) to increase training load (fatigue accumulation), players can experience short-term performance decrements without severe psychological or long-term negative symptoms. This functional OR (or short-term OR) \vill ultimately lead to an improvement in performance after adequate recovery (supercompensation effect). (Soccer example: A seven-day training camp followed by 3-4 days of adequate recovery.) Overreaching is an integral part of successful training regimes, and it can be analyzed using a multidisciplinary approach involving physiological and psychometric data. Overreaching is often utilized by coaches during a typical training cycle to enhance performance. Intensified training can result in decreased performance, but when appropriate periods of recovery are provided, a "supercompensation" effect may occur, with the player unveiling (because of reduced leveis of fatigue) an enhanced performance. This process is often used during "training camps," and it will lead to a temporary performance decrement that is followed by improved performance. In this situation, the physiological responses will compensate for the training-related stress (Steinacker et al., 2004). This form of short-term "Overreaching" can also be called "Functional Overreaching." FITNESS IN SOCCER Training continuum 1189 11.2.5 Dysfunclional ar Nan-Funclianal Overreaching (NFOR) When coaches do not sufficiently respect the balance between training and recovery, NFOR (extreme OR) may occur. At this stage, the first signs and symptoms of prolonged training distress are performance decrements, psychological disturbance, decreased vigor, increased fatigue, and hormonal disturbances. Players will often require weeks or months to recover. An example in soccer would be when a team plays competitive games twice a week for six consecutive weeks without respecting adequate recovery between games. Dysfunctional overreaching is the point along the training continuum when functional overreaching results in more persistent decreases in performance (Moore and Fry, 2007). 11.2.6 Overtraining syndrame (OTS) Although this term is frequently used, overtraining rarely occurs in soccer. OIS occurs mainly in individual athletes (especially endurance athletes) and is the consequence of an excessive training load over a prolonged period. ln most cases, OIS will occur in combination with other stressors, such as psychological, immunological, social, and so on. The confusion surrounding OIS is complicated by the fact that the clinicai features are non-specific, anecdotal, and numerous (Meeusen et ai., 2013). Ihe distinction between NFOR and OTS is very difficult, because a player will often display the sarne clinicai, hormonal, and psychological signs and symptoms. A key phrase in the recognition of OTS might be the "prolonged maladaptation" of several biological, neurochemical, and hormonal regulation mechanisms (Meeusen et al., 2013). Recovery from overtraining syndrome can take months (Kreider et al, 1998). ln a study by Morgan et al. (1988), 12 male swimmers were assessed prior to, during, and after increasing their workloads from 4,000m to 9,000m at 94% VO 2m.1x over a ten-day period. Swimmers completed a POMS (profile of mood status), muscle soreness scale, and 24-hour history each morning before starting the first of two daily training sessions. Seven swimmers successfully completed the required training regimen, but three others had difficultly completing the training requirements, and these athletes had significantly higher levels of POMS mood disturbance. Many of the physiological and psychological responses tended to stabilize after the first five days of exposure to the training stress. Three other swimmers were so severely affected by the training that they had to be dropped from the study. In those swimmers, the psychological changes were very marked. 190 1 FITNESS IN SOCCER FITNESS IN SOCCER Training continuum Training continuum 11.3 LOAD ANO LOAD TOLERANCE Overtraining, acute fatigue and overreaching are the result of an imbalance between load (physiological, mechanical, and psychological) and the load tolerance of the player. If the accumulated load exceeds the player's load tolerance for too long, functional or dysfunctional overreaching may occur, resulting in a decline in performance and a substantial risk of injury. The training process should therefore always constitute a perfect balance betvveen the accumulated load and the load tolerance. Players' load tolerances are determined individually. Within any team, there will be players who will respond positively or only barely to a training plan, depending on the nature of players and their ability to cape with the training demands and non-training stress factors. In an appropriate training plan, the player will receive an suitably individualized training stimulus (duration, intensity and frequency) that will increase the load tolerance (functional adaptation). Training is nota one-sided form of loading, and overload phenomena vary for different physical abilities. 11.3.1 Conceptual framework describing the interplay between load and load tolerance Injury threshold (load tolerance threshold) lOOo/o ô ·~ !E ] 50% ºº''º 60min 90min 120min 150min 180min Duration Fig. 11.2: This figure shows lhe effects oftraining /oad (duration x intensity) for an individua/ player. lf this p/ayer trains just be/ow the injury threshold (foad to!erance}, his or her filness wifl improve, subsequentfy increasing the thresho/d. lf the pfayer trains too far be/ow this threshofd, he or she wifl either sustain the fitness levei (retaining /oad) oreven lose it (detraining foad). Training above the injury thresho/d wifl cause overreaching and may /ead to injury. Load: Frequency Duration !ntensity load tolerance Physical fitness Lifestyle Stress Social support Fig. 11.1: Relationship between /oad (physiofogical, mechanica/, mental) and load toferance. We illustrate this based on a number of example training sessions for a player: TI: Session of ± 60 minutes at ± 30%: This load is insufficient for the player to maintain fitness. T2: Session of ± 70 minutes at ± 60%: This load is sufficient for a player to rnaintain fitness. T3: Session of ± 100 minutes at ± 55%: This load is sufficient for the player to rnake progress. The load is just below the injury threshold, so training 'vill consequently improve the player's fitness and therefore push the injury threshold higher. T4: Session of ± 120 minutes at ± 45%: Although the training parameters for this session differ from training session T3, the load is also sufficient for the player to rnake progress. TS: Session of ± 70 minutes at 70%: This load is too high for this player, so the likelihood of injury increases. T6: Session of ± 130 1ninutes at ± 70~~: This load is much too high for the player, so the risk of the player sustaining an injury because of accumulated fatigue is high. J 191 192 1 FITNESS IN SOCCER Training continuum FITNESS IN SOCCER Training continuum 1193 Tl is a 95-minute session at 30%. This is a low-endurance training session that is therefore ideal for player 1, but this training load is insufficient to elicit adaptation in players 2 and 3. T2 is an 80-minute session at 50%. This training load is ideal for player 2, because it is a good stimulus to cause fatigue and consequently adaptation. The load is too high for player 1 and too lO\V for player 3. Finally, T3 is a 75-minute training session at 70%. ln this example, the load is ideal for player 3, but too high for player 2 and much too high for player 1. 100% 60min 90min 120min 150min 180min Duration This graph perfectly illustrates the everyday situation in soccer where too much training is carried out in a group setting. For example, Hoff et al. (2002) demonstrated that players with the highest V02max had the lowest percentage of V0 2max during small-sided games. This indicates that soccer players with higher fitness leveis may not receive sufficient training stimulus to further increase their fitness when training in ateam environment (Hoff et al., 2002). Finally, we should also highlight that this is a simplified model that does not take account of the consequences arising from previous loads and recovecy and the differing effects of intensity and volume training. It clearly depicts, however, the interplay betvveen load and load tolerance. Fig. 11.3: This figure shows the shift in the player's injury threshold due to increased fitness leveis. 11.4 OVERTRAINING DETECTION SCALE The table below presents a scale that can be used for the early detection of overtraining. Overtraining phase 2 can be used as an indicator for detecting and avoiding overreaching at an early stage. Training has to be adjusted from this threshold in order to avoid injuries. 100% Injury threshold player 3 Overtraining detection scale Injury threshold player 2 ·~ É Injury threshold player 1 50% Overload zone player 1 .E Overload zone player 2 0% 60min 90min 120min 150min 180min Duration Fig. 11.4: This is a typica/ representation of a group of soccer pfayers. Here we have if/ustrated lhe overload zones for three p/ayers. P/ayer 1 is a physically weaker p/ayer. Player 2 is a physical/y moderate pfayer, and p/ayer 3 is a physica/fy strong p/ayer who is ab/e to handfe a high load. For lhe sake ofthis examp/e, we discuss three training foads, T1, T2 and T3. Overtraining phase O no pain/fatigue atai! Overtraining phase 1 player feels muscle pain/fatigue in lhe morning after waking up Overtraining phase 2 p!ayer feels muscle pain/fatigue in between exercises Overtraining phase 3 player feels muscle pain/fatigue at lhe start of the warm up but the pain/fatigue fades during warm up Overtraining phase 4 player feels muscle pain/fatigue at lhe start of lhe training, but the muscle pain/fatigues fades during training Overtraining phase 5 Muscle pain/fatigue is constantly present during lhe training session. Overtraining phase 6 Training is no longer possible. Table 11.3: Overtraining detection scale This table can be used to question the players, such as by using questionnaires or smartphone apps, when they arrive at the club each morning. This subjective infor~ation can be used by the coaches to adjust training parameters. 194 FITN ESS 1N SOCCER 1 FITNESS IN SOCCER Training continuum Trainíng continuum 11.5 TRAINING FLAWS 11.6 RELATION BETWEEN LOAD, INJURIES, FITNESS AND PERFORMANCE Several authors have discussed flaws in the training process (Harre, 1982; Fry et al., 1992; Noakes, 1991; Dalton, 1992; Fosteret ai., 1999; Bompa, 1999; Dick, 2003; Smith, 2003). These training flaws are summarized below: ln this section, we describe a theoretical concept to describe the relationship between training load, injuries, fitness and performance in soccer. We start with the scientific fundaments of our concept. • • • • • • 0 • 0 • • • • • • 0 • Improper balance between intensity and recovery Inappropriate lifestyle Insufficient support of the social environment Neglecting adequate recovery in the microcycle, mesocycle, and macrocycle sequences High volume of maximal and submaximal intensity training The overall volume of intense training is too high Excessive attention and time are spent in complex technical or mental aspects without adequate physical and mental recovery Demands on an athlete are made too quickly relative to load tolerance, compromising the adaptive process Improper technique Muscle weaknesses and imbalances Early specialization Not enough or too many hard training sessions Starting intensive training sessions without a proper "aerobic" platform Excessive number of competitions with maximum physical and psychological demands combined with frequent disturbances in the daily routine and insufficient training The player lacks trust in the coaching staff because of high expectations or goal setting that has led to frequent performance decrements or failure in the past The training load is increased too rapidly after a break from training due to illness, injury or the off-season Not altemating hard and easy training Some authors (Pyne, 1996; Daniels, 1998; Harre, 1982) have published some recommendations to avoid overtraining and elicit adaptation: 0 • 0 0 • • • • • Long-term performance goals for the season form the basis upon which the training program is designed Progressive and cyclical increase in training load Incorporating a maximum of 2-3 hard sessions in a microcycle Logical sequence to the order of the training phases Hard and easy training sessions are alternated Training process is supported by continuous scientific monitoring Intensive use of recovery strategies throughout the training program Emphasis on skill development and refinement maintained throughout the training program Underlying platform for the improvement and maintenance of general athletic abilities ! ' 11.6.1 Relation between load and performance 11 f 1 Hlgh Relation between volume of training and team success Adapted from: Ekstrand et ai. 1982 l 1 Low Hours of tra!nlng Hlgh Fig. 11.5: Relationship bet>veen volume oftraining and team success Ekstrand et al. (1982) found a direct association between team success in soccer, as expressed by league points during the year, and the volume of training. In this shtdy, the volume of training for each team was expressed as the number of practice hours in which the 15 players participated (i.e., attendance multiplied by number of practice sessions). J 195 196 1 FITNESS IN SOCCER Training continuum FITNESS IN SOCCER Training continuum 1197 11.6.2 Relation between training load and injuries ";•h Relation between training and number of injuries Adapted from: Ekstrand et ai. 1982 Relation between training load and likelihood of injury Adapted from: Gabbett & Domrow 2007, Gabbett 2010 ,,,,,~-------------------------- Low Tra!n!ng load High Fig. 11. 6: Relationship between training /oad and the fike/ihood of injury in col/ision sporl athletes (footnote: This figure is not entire/y accurate in its modification. At vef}' high loads, lhe risk of injury pfateaus, and further increases in /oad result in only minimal change in injury risk (Gabbett, personal communication) ln a study of Gabbett (2010), athletes who surpassed a predefined training load threshold were 70-fold more likely to test positive for non-contact muscle injury. Previous research reported a relationship betvveen training loads and injury rates, suggesting that the harder athletes train, the more injuries they will sustain (Gabbett, 2004). Gabbett and Domrow (2005) demonstrated that team sport athletes who perform less than 18 weeks of preseason training are at increased risk of sustaining a reinjury, while players with a low off-season V0 2max are at an increased likelihood of sustaining a contact injury (Gabbett and Dornrow, 2005). Enhancements in soccer require training loads that balance the minimum training loads required to elicit a fitness enhancement 1vith the maximum training load bearable (load tolerance) before sustaining an injury. Gabbett and Domrow (2005) found a relationship between the log of training load per week and the odds of injury during the pre-, early-, and late-competition phases. These results confirm earlier research that demonstrated that the likelihood of sustaining an injury is higher in the preseason preparation period when training loads are greatest (Gab- Hlgh Hours of tralnlng Low Fig. 11. 7: Relationship between volume of training over a soccer season and the number of injuries Ekstrand et ai. found a curved relationship between injuries and training in soccer. Teams with fewer than average training hours (<1400 hr/team) showed an increasing number of injuries with increased training, while teams with greater than average training hours showed a decrease in injuries with increased training (p < 0.01). The researchers attributed the increasing number of injuries with increased training to prolonged exposure. The fewer injuries in teams with higher training volumes is explained in the study as a reflection of the well-known fact that well-trained athletes sustain fewer injuries. The fact that players in this study did not sustain more injuries with increased training could be dueto the levei of the players (Division 4 in Sweden). These players are probably not exposed to training loads that are sufficient to elicit overreaching levels and surpass injury threshold levels. 11.6.3 Relation between number of injury days and performance H!çh Relation between number of injury days and the final league standing Adapted from: Arnason et ai. 2004 bett, 2004). HJgh posltion Final le~gue standing Low po~ition Fig. 11.B: Re/ation between number of injury days and the final league standing 198 1 FITNESS IN SOCCER FITNESS IN SOCCER Training continuum 1199 Training continuum Arnason et al. (2004) investigated the relationship between the number of injury days and the final league standing. Injuries to key players, as well as a reduced number of available players, are expected to affect team performance. Although injured players can be replaced by substitutes, the researchers observed a trend toward a significant relationship between the total number of injury days per team and team success. They explain this association by the fact that in Iceland, soccer teams have limited resources to replace injured players. ln the major European leagues, however, teams are in a position to buy new quality players when needed, so it is possible that injuries could be seen to be more of a financial issue and less directly related to team performance on the pitch. The association between injuries and final league standing was confirmed in a study by Birale et al. (2013). The researchers reported strong correlations between injury incidence and high league rankings in the Qatari Stars League. They also found a significant relationship between a lo\v number of injuries and the number of games won, number of goals scored, goal difference, and total number of points in a season. Hãgglund et al. (2013) investigated the influence of injuries on team performance in soccer and found that a lower injury burden and higher match availability were related with higher final league ranking. Similarly, lower injury incidence, lower injury burden, and higher match availability were related with increased points per league match. The researchers concluded that injuries had a significant influence on performance in league play and in European cups in male professional soccer. They therefore stressed the importance of injury prevention to increase a team' s chances of success. 11.6.4 Theoretical concept on the association between load, injuries, fitness and performance Relation between load, injuries, fitness and performance H!gh - ~ • - ':r_; ...:.. ~ ••ili·• Injuries - - r Fitness J ... ·· - -M-Performance ••• 1 i-·~·ili-·····l&:·····i.-.; .... r'"·· .. SUMMARY lo •• 1 2 low 3 4 This is a hypothetical representation of the association between training Ioad (x-axis) and injuries, fitness and performance (y-axis). Injury: Injuries are often associated with reductions in performance. It is not clear, however, whether poor performance is the cause or the effect of high injury rates. The likelihood of training injury increases with mounting training loads (Gabbett, 2004; Gabbett and Domrow, 2005; Gabbett and Ullah; Gabbett, 2010; Gabbett and Ullah, 2012). ln this graph, the rate of injury increases exponentially because it is assumed that the higher the training load, the more players will surpass their injury thresholds. Fitness: The fitness of players increases with increasing training loads. At some point (point 8 on the graph), however, the load will become too high for the load tolerance of the players. Overtraining will occur, and additional training stimuli will be detrimental to fitness. Performance: Performance is influenced by two antagonistic factors. Injuries affect performance in soccer negatively (Arnason et al., 2004; Hãgglund et al., 2013; Eirale, 2013), while fitness affects performance positively. Point 6 on the graph indicates the optimal relationship between training injury and fitness. Injury rates start to increase, but due to the raised levels of fitness, performance reaches its peak level. Fitness leveis increase further with increasing training load (point 7), but the injury rates start to increase exponentially. These injury rates influence performance negatively, so performance starts to decrease. The prevention of injuries and the enhancement of fitness are often regarded as two discrete pursuits at different ends of the training continuum. Medical and technical staff often appear to have different goals. Medical staff see the value in monitoring training loads to reduce injuries, while technical and sports science staff would like athletes to complete high training loads to elicit positive physical adaptations. The key performance indicator of ateam doctor or physiotherapist should theoretically relate to the "injury" curve on the graph, and they might even be more comfortable with a low training load and a reduction in training (Orchard, 2012). Some soccer managers often use injuries as an excuse for poor results because there is still a common view that injuries are generally random and therefore out of a manager's contra! (Orchard, 2012). s Tralning load (AU) 6 7 8 9 10 High Fig. 11.9: Relationship between training load and fitness, performance and injuries (modified from Orchard, 2012) A successful periodized soccer training program must involve overload in order to induce beneficial training adaptations, but it must also avoid the combination of excessive overload and inadequate recovery. In order to optimize perfo1mance enhancement and ensure that players reach the fitness levei requiredr scientific monitoring of training loads is essential to help players avoid accumulating excessive fatigue and surpassing their own individual load tolerance and injury threshold. FITNESS IN SOCCER Fatigue FITNESS IN SOCCER 2001 Training continuum i 201 REFERENCES 1 Amaoon, A., Sigurd%on, S.B., Gudmundr,son, ,\, and Holme, L, 2{){).j. Phyoic,11 fün~r.. injurie,;, and tcam pcrfonnanre in socccr. Medicine and Scfonre in SporbJ and Excrosc, 36(2), pp.271.>-285. Budgelt, R., Ncwsholme, E., Ldrniann, 1'L, Sharp. 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On thc valucoftcam medical slafi: can the "Moncyball" approach bcapplicd to injuries in profossíonal football? l.lr J Sports Mcd, 13(13), pp.9f>3.5. On:hard, J.W., James, T., Portur,, M., Kountouris, A. and Oennis, R., 2009. Fa>t bowlcr.; ln cricket dcmon:;lratc up to 3· to 4·wcck dday betw°"'n high workloads and inc..,aoed risk ofinjury. AmJ Sports Mcd, 37(6), pp.1186-92. Orchurd, 2012. Who is to biame for ali thc footbal! injuries? !online] Availablc at: <;http:/ fblogs.bmj.rom/bjsm/2012/06/20/ w fio..is--10· blilmL.. for·all· thc· foo tl>il ll·injuric.< /> Prne, O., 1996. Tiw periodizalion oi swimming training Qt lhe Australian tnstitute ofSport. Sporls Coach, 18, pp.34-8. Smith, D.J., 2003. A framcwork for undcrstanding the training proccss Jc,1ding to elite pcrfonnnncc. Sports Mcd., 33(15), pp.1103·26. Stcinackcr, J., Lonncs, W., Liu, Y., Rcis.mcckcr, S., Opitz·Grc%, A., Ilallcr, B., Gtinthcr, K.. Pclerson, K.G., Kallus, K.W., Lchmann, M. and Altenburg, D., 2000. Training of Junior Rowcrs before Wor!d ChampionEhips. Effccts on pcrfonnance, moodstatc andsdectcd honnonal and mctabolic reoponses. J Sports Mcd Phys Fítness, •IO, pp.327-35 .. FATIGUE Jan Van Winckel, Kenny McMillan, Paul Bradley, David Tenney, Werner Helsen 12.1 INTRODUCTION Throughout this textbook, the management of fatigue is considered as a critical component to successfully plan a soccer season. Before discussing in more detail the methods of managing fatigue, let us first examine the term fatigue in this chapter. There are many definitions of fatigue in the existing literature. Fatigue is mostly defined as an acute impairment of performance that includes both an increase in the perceived effort to exert a desired force or povver and / or any reduction in the ability to exert maximal muscle force or power (Gandevia, 2001). ln soccer, fatigue is generally referred to as an inability to maintain physical and technical performance during a match. The exercise intensity of top-class soccer players declines in periods during a game, most likely due to fatigue, particularly toward the end of the match (Mohr et ai., 2005). Although extensive research has examined the causes of fatigue in soccer, a number of questions remain. The molecular basis of the fatigue process, in particular, is still not understood completely. There are different causes for different types of sport. For example, the fatigue induced by an SOOm run is completely different to that of a marathon. The loss of muscle function is quite complex and varies from reduced functioning of the motor cortex in the brain to the binding of actin and myosin. There are various causes of fatigue, and scientists typically divide them into central and peripheral factors. Fatigue can be classified as central when the origin is proximal and/ or peripheral when the origin is distal to the neuromuscular junction (Gandevia, 2001). Central fatigue seems to be the main cause of the decline in maximal voluntary contraction and sprinting ability, whereas peripheral fatigue seems to be more related to increased muscle soreness and therefore may be linked with muscle damage and inflammation (Rampinini et al., 2011). FACULDAIJ~ n~ DESPORTO DA UNIVERSIDADE DO PORTO zoz I FITNESS IN SOCCER Fatigue FITNESS IN SOCCER Fatigue 12.2 FATIGUE IN A SOCCER MATCH Rahnama et ai. One of the consequences of playing a match is a decrease in muscle power, which is reflected by a drop in physical capacity toward the end of the match. Research initially primarily focused on peripheral factors, such as diminished energy stores, increase in body core temperature, fluid loss, muscle damage and various combinations of factors. Recently, more attention has been paid to the central factors, mental fatigue and the role of the nervous system. Generally speaking, it can be concluded that physical performance decreases toward the end of a match (Rampinini et al., 2008), although one cannot discount the influence of tactics and context (e.g., match importance, location, standard and score board) on the physical performance of players. Therefore, it has been suggested that fatigue can be more efficiently quantified using performance measurements (e.g., the distance run during a match). Evidently, this is a difficult task because players do not always tax their full capacity during a match and only usually tax themselves during intense periods of match play when they carry out a flurry of high-intensity activities with minimal recovery. Recent research pointed out that senior soccer players are able to cope with the high demands of match play and demonstrated that no differences were found in examples such as counter movement jumps executed both directly before and after a match (Cortis et al., 2013). It might be that teams and players pace their efforts in order to sustain the sarne work rate throughout the duration of the game, suggesting that players may exert an effort below their physical capacity in the first half as an energy conservation technique (Carling et al., 2008). (2003) Research Bangsbo et ai. (1991) Findings The distance covered in lhe first half was 5°/o greater than in the second half. Bradley and Nonkes (2013) Players covering the most total distance in lhe first half illustrated lhe mos! pronounced declines in the seconci half. This was not evident for players covering moderate anci low first half distances Bradley et ai. Players ran 21 % less distance at high intensity in lhe last 15 minutes of lhe match compareci with the first 15 minutes. (2009) Bradley et ai. (2010) Krustrup et ai. (2006) The distance covered at high speed was 18o/o lower in lhe last 15 minutes of lhe malch compareci with lhe first 15 minutes. Players' performance over a 30m sprint dropped ciuring lhe break and immeciialely after the match. Mohr et ai. (2003) The distance covereci in lhe second half was 160m less lhan in lhe first half. Mohr et ai. (2003) A 5-minute perioci of increaseci intensity is fol!oweci by a period of significantly less activity. Rahnama et at. The risk of injury was grealer in lhe firsl anci lasl 15 minutes of lhe match. (2002) Gaudino et ai. (2010) They conc!ucieci lha! there are significanl differences between lhe first anci second ha!ves of lhe game. The distances covereci in the seconci half, when compareci to the first half, are significantly lower for ai! categories of run (p<0.05). ln lhe seconci half, lhe dislance covered ai very high intensity is significantly lower (p<0.01), while lhe number of recovery times greater than 120s increases significantly compareci to lhe first half (p<0.01 ). Rahnama et al. (2006) This study compareci the strength (measured wilh isokinetic equipment) of the knee flexors (hamstrings) and the knee extensors {mainly quaciriceps). The strength of lhe two muscle groups haci already decreased ciuring the break and ciiminisheci further towarci the end of lhe match. The ratios between both muscle groups fell, reducing lhe stability of the knee joint. ln this stuciy, the fatigue of a number of muscles in a soccer match was measured. This shows that fatigue during a match increaseci for various muscles (rectus femoris, biceps femoris, tibialis anterior) towarci lhe enci of the game. (2007) A top ltalian team covers a greater distance anci works more ai high intensity in top games when compareci with games ata lower levei. Rellly (2003) Diminished performance is inversely proportiona! to VOzmo>' Reilly et ai. Diminisheci sprinting performance was observeci at the enci of a match. Rampinini et ai. (2002) Strudwick and Reilly (2001) The ciistance covereci ciuring a match has increased significantly since the introciuction of lhe Premier League. Van Gool et ai. Van Gool et al. stuciied lhe ciistance run during matches in the Be!gian league. A distance of 444m was run in the first ha!f. (1988) Tabfe 12. 1: OveNiew ofexisting soccer Jiterature. 1 12.3 UNDERLYING MECHANISMS OF FATIGUE 12.3.1 Metabolic effects The decrease in muscle function is referred to as peripheral fatigue. During a soccer match, maximum strength rarely decreases by more than 30% because of new motor units being recruited when needed. ln addition, synergistic muscles can help compensate for any loss of strength. Muscle strength fa11s by around 10% after brief intense exertions and can drop to 30% after long physical exertions. This fatigue could be caused by metabolic factors, such as a reduction of adenosine triphosphate (ATP) and creatine phosphate (CP) stores, a depletion of muscle glycogen, or drops in pH due to muscle acidosis, as well as biochemical factors such as chlorine (CI·), sodium (Na+), potassium (K+), calcium (Ca2+), lack of oxygen (hypoxia), and structural damage (e.g., micro-traumas). Diminished functioning of a muscle can also be of a neural origin through the reduced functioning of the motor cortex in the brain. This process is referred to as central fatigue. i 203 204 1 FITN ESS 1N SOCCER FITNESS IN SOCCER Fatigue Fatigue 12.3.2 Glycogen stores The depletion of glycogen stores in the muscles can be a contributing factor to fatigue in soccer. ln a study by Krustrup et al. (2006), a high number of individual muscle fibers were partly depleted of glycogen toward the end of a soccer match. They concluded that low glycogen leveis in individual muscle fibers explained the impairment in sprinting at the end of the game. Furthermore, a decrease in blood lactate toward the end of matches indicates a lower utilization of glycogen (Bangsbo, 1994). Players also complete fewer sprints and work less "off-the-ball" in the second half if they start a match with low glycogen stores (Saltin, 1973). However, blood glucose concentration does not reach criticai values during a soccer match (Ekblom, 1986). Glycogen stores can be increased through training adaptations. Although lactate and acidosis are often referred to as possible causes of fatigue in soccer, it is unlikely that elevated muscle lacta te and lowered muscle pH cause fatigue during a soccer game (Mohr et al., 2005). 1.s 7.4 "8 7.3 ~ 7.2 :r .5 ~ '·' 7 1 2 3 4 6 7 5 Lactate {mmol/I} 8 9 10 11 Fig. 12.2: Relation between pH in blood and /actate. Acidosis is not caused by lactate but rather by processes closely linked to lhe production of /actate. o 2 3 Duratfon (hours) 4 5 = - Perceived exertion - - Muscle glycogen Fig. 12. 1: Relationship between muscle g/ycogen and perceived exertion o ver lime. Consuming an energy drink containing carbohydrates (CHO) during the halftime interval, or using good nutrition strategies during the days leading up to the match, can therefore delay fatigue (see Chapter 4). 12.3.3 Lactate and Acidosis There is a discrepancy bet'vveen blood lactate and muscle lactate. Muscle lactate increases linearly with the intensity. while blood lactate increases exponentially. The intracellular accumulation of lactate per se is nota major factor in muscle fatigue (Allen et al., 2009). The formation of lactate rather delays the fatigue process. One of the consequences of anaerobic glycolysis is that hydrogen ions are produced in addition to lactic acid. This causes acidosis in the cell. Acidity is expressed as a pH value. The higher the pH value is, the more alkaline the sample is. The pH value can vary between O and 14, with 7.0 being the neutral value. Everything greater than 7.0 is alkaline, and everything less than 7.0 is regarded as acidic. The pH value in a resting muscle is approximately 7.4. This value is important for most enzymes, because they only function in an optimum way at values of around 7.4. This is why there are a number of buffers built into the cell to absorb these hydrogen ions. Over time, however, the buffer capacity of cells is exceeded, and the pH value in a cell can fall to 6.9. 12.3.4 Fatigue resulting from lhe rate ofthe energy supply Muscles need oxygen in order to tum over energy via the oxidative system. Oxygen is transported to the muscles by the blood. In the blood, hemoglobin binds with oxygen. The quantity of hemoglobin in the blood determines the speed at which fatigue occurs during periods of intensive physical exertion. A second factor is the oxygen-binding capacity. At high altitudes, the 0 2 pressure of inhaled air is lower than at sea level, causing fatigue to occur more rapidly. 12.3.5 Exercise-induced muscle damage (EIMD) and delayed onset of muscle soreness (DOMS) A player may feel pain in his or her muscles after a match or strenuous training. This is often attributed to a buildup of lacta te in the muscles, but this is an incorrect hypothesis. Muscles are put under strain during physical activity, and if a muscle is overloaded (in particular eccentrically), microtraumas occur in the muscle tissue, resulting in damage to muscle cells and capillaries. This mechanism develops an inflammatory reaction, which can be established via a blood analysis. Reduced muscle force, increased muscle soreness, increased concentrations of blood creatine kinase (CK) and myoglobin (two indicators of muscle damage) are higher after intensive physical activity, and these may be factors that contribute to performance impairment after a match (Ascensão et al., 2008). Furthermore, overtraining causes a buildup of residual substances, causing the capillaries to dílate so the residual substances are easier to remove. This involves an accumulation of fluid in the muscles, causing the blood vessels to contract and resulting in a Jack of oxygen. The pain a player feels one or two days after strenuous exertion is therefore the result of pressure on the pain nerves in the muscles and the release of residual substances that stimulate the nerves. ! 20s ZOG I FITNESS IN SOCCER Fatigue 12.3.6 Muscle cramps A cramp is a painful involuntary contraction of a group of muscles. Cramps mostly occur at the end of a soccer match. It is often claimed that cramps are a result of lactate or lack of fitness. Both claims are most probable not true, because muscle cramps mostly occur in soccer players who have reached a certain levei of fitness. Muscle cramps can most likely be attributed to loss of fluid during the match and muscle fatigue. Minerais such as calcium, iron, magnesium, potassium and sodium are lost insweat. Sweat contains approxirnately between 300 and 1500 mg of sodium per liter. Since soccer players may lose more than three liters of water during matches (Mustafa and Mahmoud, 1979), they can also lose 3,000mg of sodium during a match. Sodium lasses in three liters of sweat can equal or exceed daily intake (3,000-4,000mg) and lead to deficiencies. To prevent cramps, it is advisable to drink at regular intervals and eat a balanced diet during the week. With some players who have high sodium concentrations in their sweat, it is often noticeable that their shirts display areas of sweat with white fragments after physical exertion. These white fragments are the lost sodium. Stofan et al. (2003) reported that American Football players with high sodium concentrations in their sweat may be particularly susceptible to muscle cramps (Stofan et al., 2003). Bergeron (2003) suggested that failure to adequately replace sweat salt losses predisposes players to muscle cramps in teruris and proposes that these can be prevented by ensuring an adequate salt intake. The most common form of sodium is sodium chloride, or table salt. Milk and celery also naturally contain sodium, as does drinking water, although the amount varies depending on the brand of mineral water. Water is commercially available that contains larger quantities of electrolytes. ln hot or humid conditions, it is reasonable to plan an intake of up to l,OOOmg (one-half teaspoon of salt) of sodium per liter of fluid loss. 12.3.7 Temperature and fluid loss An increase in body core temperature is beneficial for performance. Warming up the muscles prior to the game and after the half-time break raises the performance levei. However, an excessively high body temperature (hyperthermia) reduces a player's performance. Factors such as dehydration and hyperthermia have been suggested as mediators responsible for the development of fatigue in the later stages of a soccer game (Reilly, 1997). This is most likely a central form of fatigue, whereby a criticai core temperature of 40ºC cannot be exceeded (Morrison et al., 2004). However, there may not be an exact criticai threshold for thermoregulation, but rather one that varies \.Vith training, acclimation and time of day (Noakes, 2006). Various publications have demonstrated that training and competing in hot and/ or humid conditions may result in reduced performances (Edwards and Clark, 2006; Duffield et ai., 2009). A study of Mohr et ai. (2010) provides direct evidence of decreased repeated sprint and jump performances induced by soccer match play and pronounced reduction in high-intensity running toward the end of an elite game played in a hot environment. They conclude that this fatigue could be associated with training status and hyperthermia/ dehydration. FITNESS IN SOCCER 1 Fatigue 12.3.8 Early dismissal Carling and Bloomfield (2010) examined the effects of an early dismissal (after five minutes of play) on work rate in a professional soccer match. The researchers propose that in 11 vs. 11, players may not always utilize their full physical potentials, as this match illustrated an increase in overall work rate when reduced to 10 players. They conclude that ateam with 10 players is likely to incur higher levels of fatigue, and tactical alterations may be necessary and/ or players may adopt a pacing strategy to endure the remainder of the match. 12.3.9 Travei Elite soccer players are frequent travelers and sometimes have to cross multiple time zones. These journeys are undertaken to participate in club or international competition in single engagements or for more prolonged tournaments, such as the World and European cups. On other occasions, soccer players take advantage of altitude or seasonal differences in weather conditions to attend training camps in other parts of the world where the climate is more favorable to strenuous exercise (Reilly et al., 2007). Traveling is associated with negative effects such as stiffness because of being in a cramped posture for too long, anxiety about the journey, the change to an individual's daily routine, and dehydration dueto time spent in the dry air of the aircraft cabin. Travel fatigue lasts for only a day or so, but for those who fly across several time zones, there are also the longer-lasting difficulties associated with "jet lag." The problem of jet lag can last for over a \.Veek if a flight crosses 10 time zones or more and reduce performance (Waterhouse et al., 2004). The body clock gradually adapts to the local time of the new environment, and when this process is complete, the symptoms of jet lag disappear (Lemmer et al., 2002). It appears also ineffective to train hard at home prior to embarkation, because arriving tired at the airport of departure may slow the adjustment later (Waterhouse et al., 2003). The sarne negative effects can be experienced while attempting to shift the phase of the body clock in the required direction for some days prior to departure, and this is counterproductive because the quality of training and subsequent performance can be compromised by this strategy (Reilly and Maskell, 1989). Some data have shown that eastward travei is more detrimental to performance. This is because the body clock's rhythm is naturally longer than the 24-hour light-dark cycle (approximately 25-26h long), so it is easier for the body to adapt to changes that lengthen the day rather than shorten it (Leatherwood and Dragoo, 2013). 207 2os I FITNESS IN SOCCER Fatigue FITNESS IN SOCCER Faâgue 12.3.9.1 Recommendations to decrease the effect of air travei on performance 12.4 EFFECTS OF FATIGUE (Leatherwood and Dragoo, 2013): 0 • • • • 0 o 0 0 ln advance of travel, shift the body clock to the new time zone using gradual, one-hour-a-day shifts in sleep scheduling. This recommendation contradicts the advice oi Reilly and Maskell (1989). Circadian phase shifting can be facilitated by proper timing of Iight exposure an<l the use of supplemental melatonin, taken orally in doses ranging from 2 to5mg. Exposure to natural daylight is preferred over exposure to artificial light. Expose travelers to social contact at times appropriate for the local time at the destination. Avoid caffeine during travei, as this stimulant can interfere with appropriately timed restorative sleep and alter the ability to effectively adapt to a new time zone. Short (20-30 min) naps can be helpful in recovering from sleep deprivation and restoring a normal state of arousal. Consume extra fluids for the duration of air travel to combat dehydration. Avoid alcohol and caffeine, as these act as diuretics and can increase fluid losses. If possible, make arrangements for dietary selections that are optimal for individual performance. While travelling, eat smaller meals before and during flight. Then, upon arrival, time meals to match habits appropriate to the destination. If travelling outside of the country, avoid non-bottled water and raw or minimally cooked foods, as well as peel fruits and vegetables that have been washed. Performance-related symptoms General performance Decline Recovery periods lncrease Technical execution Decline Kicking speed Decline Kicking precision Decline Number of bad passes lncrease Concentration Decline lncrease Fatigue Test-related symptom Muscle strength Decline Muscle speed strength Decline Coordination Decline Time (endurance, speed, agility, repeated sprinting capacity) Jncrease Technical execution Decline Technical precision Decline Subjective fatigue lncrease Subjective muscle pain lncrease Decision making lncrease or remains lhe sarne Tabfe 12.2: Overview ofthe effects offatigue in soccer. 12.4.1 Overview of the effects on physical performance ln the preceding paragraphs, we gave an overview of the effects of fatigue during soccer matches: 0 Decreased distance in the second half 0 After intense periods in the first half, players' sprint performances were significantly reduced (Krustrup et ai., 2003) o Peak sprinting speed was higher during the first five minutes of the first half when compared with the second half (Bangsbo et al., 2010) 0 Less high-intensity activities (Andersson et al., 2008) o Fewer sprints • Impaired sprint performances in the initial phase of the second half when compared with the first half (Mohr et ai., 2004) o Longer recovery times between actions (Bangsbo et al., 2010; Bangsbo and Mohr, 2005) • Decreased activity after the most active periods • Decreased passing precision (Rampinini et al., 2008) o Mean sprint length decreased toward the end of the game (Mohr et al., 2010) • Less distance at high intensity • Increased risk of injuries 0 Diminished maximum speed (Anderson et al., 2008) i 209 210 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue Fatigue 12.4.2 Technical skills If fatigue increases, this will not be at the expense of techniqu~ in the first instance. This has been evidenced by Davids et aL (2003) in their "dynamic systems theory," meaning that a reorganization of movements will produce a technical variation in the first phase, but the output or result will remain the sarne. When a ball is kicked, for example, the movement is carried out through different joints (i.e., hip, knee, and ankle) and muscles. A reorganization of the motion will cause the movement to be executed differently, but the output will remain the sarne on account of the body deploying other motor units. ln the second phase, both the technique and the result are diminished (i.e., "technique deterioration"). ln a soccer match for example, kicking speed and accuracy will decrease as fatigue increases (McMorris and Rayment, 2007; Appiantono et ai., 2006). This was confirmed by Russell et ai. (2013) when they demonstrated that soccer-specific exercise influenced the quality of performance in gross motor skills, such as passing and shooting. Jordeta et al. (2007) investigated the role of fatigue in taking penalty kicks and found a trend that was in the direction of more goals with shorter playing times. 12.4.3 Biomechanical factors In sports •vhere speed has to be used for a relatively long period, such as sprinting, speed diminishes (e.g., by around 7% in the lOOm and almost 20% in the 400m) (Sprague and Mann, 1983). This is caused, in particular, by decreased stride frequency and increased contact time with the ground. Maximum speed also diminishes quickly in swimming. For example, the length of a breaststroke decreases by more than 15~~ as fatigue increases (Thompson et al., 2000). 12.4.4 Decision making Although only a limited number of studies have looked at the relationship between fatigue and decisionmaking (McMorris et al., 1999; Royal et al., 2006), there is a tendency for decisions to be taken more quickly •vhen athletes are fatigued. This may be explained by greater exercise-induced arousal (Presland et al., 2005). 12.4.5 Subjective fatigue A great deal of research has been conducted in relation to the perception of fatigue (Baker et al., 2007; St Clair Gibson et ai., 2003; Baldwin et al., 2003; Burgess et al., 1991). This subjective fatigue is measured based on the Borg scale or rate of perceived exertion (RPE). This perceived fatigue is driven by central factors, but it is mostly determined by peripheral fatigue, such as dehydration, lack of oxygen, raised body temperature, low glycogen reserves, and low blood sugar levels. 12.4.6 Psychological factors Research has shown that verbal encouragement can improve performance (Gandevia, 2001). Athletes are able to delay their fatigue when they receive encouragement. A "hostile audience" can also reduce motivation and intensity, although this was mainly demonstrated among non-athletes (Fisher, 1976). Players will also get more yellow cards at away games than in home matches, especially when the team is losing. The number of yellow cards given to a team is higher toward the end of a match. This does, of course, also have something to do with the greater risk taken by teams toward the end of a game. The presence of competitors likewise influen- ces the delaying of fatigue and leads to better results (Wilmore, 1968). Finally, it has also been shown that the stress hormone, adrenaline, was higher before and after official matches as opposed to friendly matches in tennis (Ferrauti, 2001). Belgium first division (5 seasons) Away Home Quarter Win Drm.'I Los! Win Draw Lost 0·15 16-30 513 312 321 407 429 825 191 412 3145 46-60 61-75 76-90 Over time S93 408 S16 608 79 Netherlands first division (5 seasons) Home Away Quarter Win Draw Lost Win Draw Los! 0-15 16·30 3145 46·60 61-75 76·90 Over lime 359 230 244 276 278 sas 132 276 404 323 390 379 68 Tab/e 12.3: Overview of yel/ow cards given in the Belgian and Outch first dfvision o ver 5 seasons. 12.5 COUNTERING FATIGUE Fatigue at the end of a match can be countered. Physical activity can be handled economically, of course, so that there is sufficient energy left at the end of the match. However, there are also other strategies for counteiing fatigue. 12.5.1 Training The relationship between a player's fitness and the distance covered in a match has already been discussed in detail. Although this fitness is, in part, determined genetically, it is of course also defined by the quantity and quality of training. Mohr et al. (2010) demonstrated a significant correlation between training status and fatigue development during match play. In another study of Mohr et al. (2003), the physical performance of players during matches was examined. The researchers showed that the number of training sessions during the week was related to the distance covered at high intensity. Moreover they showed that that physical performance decreased significantly if the normal training program was interrupted by a number of matches. Well-trained athletes thus cover greater distances at different speeds and need less time to recover between high-intensity activities. i 211 212 1 FITNESS IN SOCCER Fatigue 12.5.2 Use of substitutes A reduced work rate bet\veen playing halves could be countered by the strategic use of substitute players. Substitutes run a considerably greater distance in the last 15 minutes than players who are involved in the entire match (Di Salvo et al., 2007). This was confirmed by a study of Carling et al. (2010). They demonstrated that midfield substitutes covered greater overall and high-intensity distances and had a lower recovery time between high-intensity bouts when compareci with other rnidfield teammates who continued the match. Forwards covered less distance in their first ten minutes as a substitute compareci to their habitual work-rate profile in the opening ten minutes when starting matches, but this finding was not observed in midfielders. The authors suggest that it may be linked to an inability of these players to "get into the game." The strategic use of substitutes can help a team's physical performance. 12.5.3 Acclimation The negative effects of competing in heat (hyperthermia) or at a high altitude (reduction in oxygen) can be countered by acclimation strategies. The adaptations are dictated by combinations of environmental and individual characteristics (Maeda, 2005). Heat The elevated tolerance induced by the acclimatization of internai temperature is about 0.2ºC (Patterson et al., 2004), although it should be noted that some athletes will never adapt to exercising or competing in heat. Altitude Altitude affects athletic performance in a negative manner. The reduction in oxygen partial pressure in the atmospheric air, because of altitude ascent, reduces oxygen availability and consequently reduces performance. FIFA banned international matches above 2,500 meters in 2007 and suspended, under pressure, the ban in May 2008. Traveling to lower altitudes does not affect performance, but traveling to a higher altitude has negative effects. In particular, away teams perform poorly in Quito, Ecuador (2,800 meters), and La Paz, Bolivia (3,600 meters). However, away teams do relatively well in Bogotá, Colombia (2,550 meters) (Williams, 2011). Athletes may benefit from altitude acclimation to increase their performance. The performance-enhancing effects, such as increased red blood cell count, could increase performance back at sea level. Although the effects of acclimation on performing at high altitude has been demonstrated in various research, Aughey et al. (2013) concluded that neither 13 days of acclimatization nor lifelong residence at high altitude protects against the detrimental effects of altitude on the match activity profile (Aughey et al., 2013). Recent resea:ch by Buchheit et al. (2013) examined the effects on performance and physiolog1cal responses to a 14-day off-season training in heat. The researChers postulate that the combination of heat and hypoxic exposure during sleep / training might offer a promising "conditioning cocktail" in team sports. FITNESS JN SOCCER Fatigue 12.5.4 Tapering ln the following section, we will see how fatigue is managed in order to prepare players for matches in an optimum way. One of these "fatigue management" strategies is tapering. Adequate tapering strategies have been shown to improve performance and delay fatigue (Coutts et al., 2007). Bosquet et al. (2007) performed a meta-analysis and suggested that the optimal strategy to maximize performance is a tapering intervention with a two-week period where training volume is progressively decreased by 41-60% but without any modification to either training intensity or frequency. 12.5.5 Nutrition The use of supplements like high-CHO drinks and caffeine may delay fatigue. The potential of low-dose caffeine ingestion (2-5mg/kg of body mass) to enhance endurance performance is well established. However, in the case of soccer, care must be taken not to overdose because visual information processing might become impaired (Hespel et ai., 2007). Good nutritional strategies during the week are extremely important for replenishing the glycogen reserves in the muscle to the maximum, as well as for providing sufficient proteins to help muscle development and minerals to improve the functioning of the muscles. The physical requirements of soccer training and match play draw heavily on players' CHO stores, so the benefits of good nutritional practices for performance and health should be an essential part of players' education, particularly for the parents of young players (Williams and Serratosa, 2006). 12.5.6 Pre-cooling The use of pre-cooling strategies prior to exercise significantly delays the occurrence of fatigue and improves performance (Duffield et ai., 2010; Quod et al., 2008; Castle et al., 2006). The logic for this is that pre-cooling will extend the time before reaching the criticai core temperature (Price et ai., 2009). Although evidence for the transfer of these findings to a valid soccer environment is limited, pre-cooling may reduce physiological and perceptual loads to improve performance for soccer training and competition in hot enviromnental conditions (Duffield et al., 2013). However, these pre-cooling effects are largely lost during the first half. Direct skin cooling >Vith wet/ cold towels (Marsh et al., 1999) or holding the hands in cold water during the break is a cheap method for keeping the body temperature as low as possible (Goosey-Tolfrey, 2008). Drinking ice-slushies and water can also improve performance in very warm environments (Ross et al., 2011). Duffield et al. (2013) investigated the effects of field-based pre-cooling strategies (ice-vests, cold towels, and 350 mL ice-slushie drinks) for professional soccer players during training and competition in the heat. The researchers presented equivocai findings for the effects of pre-cooling for professional soccer players during competitive training and matches in the heat. However, performance and thermoregulatory response trends showed the sarne positive similarities to previous laboratory evidence. 12.5.7 Recovery Like every important form of training, adequa te recovery is an essential part of training. ln the following chapter on fatigue-management strategies1 we will discuss recovery strategies extensively. l zl3 FITNESS IN SOCCER Fatigue FITNESS IN SOCCER 2141 Fatigue 12.5.8 Sleep Sleep rernains one of the biggest mysteries of general daily life and sports performance in particular. As a state that seemingly freezes all productive activity and puts animals in danger of being caught by predators, sleep must serve an important purpose because it has survived so many years of evolution (Sehgal and Mignot, 2011). It is common sense that a "good tiredness" (understood as being physical) leads to a "good sleep" and, conversely, that a state of "being off form" follows "a bad night" (Davenne, 2009). Athletes are highly sensitive to any kind of disruptive factors that can desynchronize their circadian rhythms, such as sleep loss, jet lag (Waterhouse et al., 2000), or irregular schedules due to training or competitions (Davenne, 2009). It has long been proven that insufficient sleep can substantially reduce fitness (Bougârd et al., 2006; Reilly and Edwards, 2007). Information-processing abilities will also not be as efficient. When sleeping, the brain processes the information it receives during the day. Finally, insufficient sleep results in emotional instability. The exercises will feel more difficult, and mental toughness will diminish. When sleeping, people mostly spend 90 minutes ín the first four sleep phases before entering the REM period. The first cycle of REM sleep lasts around 10 minutes, with the subsequent REM cycles becoming increasingly longer. The final REM phase lasts as longas an hour. REM sleep accounts for around 20-25% of the total time spent sleeping by an adult. Professional players are advised to have a short (less than 30 minutes to avoid sleep inertia) and daily regular sleep period at the beginning of the afternoon. Finally, sleep extension (getting as much extra sleep as possible) may help minimize the effects of accumulated sleep deprivation, and this could be a beneficial strategy for optimal performance (Dement 2005). Tips for a good night's sleep: o Make sure you are distracted as little as possible by night-time noise. 111 Make sure the surroundings are dark, because darkness is the evolutionary signal for sleep. Environmental light, especially the altemation of light and darkness due to the rotation of the earth, ís one of the principal time-givers, and it synchronizes the internai clock (Boivin et al., 1994). o Make sure the room is not too cold or too hot. A temperature of 18ºC is ideal. 111 Make sure you have a good mattress, a good pillo\v, and sufficient space. People change their sleeping position around 40-60 times in a night SUMMARY Fatigue in soccer generally manifests itselfs as an inability to maintain physical and technical performance during competitive match play. It is not unusual to see intensity in soccer players declining in certain periods during a game, especially in the last 20 mins. This chapter has identified that there are various causes of fatigue, and they are typically described as either central or peripheral fatigue. Central fatigue is when the origin is proximal to the neuromuscular junction, whereas peripheral fatigue is when the origin is distal to the neuromuscular junction. Central fatigue seems to be the main cause of the decrement in strength and sprinting ability, while peripheral fatigue seems to be more related to metabolic disturbances and increased muscle soreness. Improved physical fitness and good nutritional practice can help to attenuate the fatigue experienced during match play. It is also important that residual fatigue from n1atch play is dealt with as effectively as possible using specific recovery strategies. Fatigue management and recovery strategies are now discussed in the following chapter. REFERENCES Allc11, N.E., Carming, C.G., Shcrrington, C. and Fung, V.S., 2009. Brodykincofo, rnusclc wcokncoc. and rcdu"'d muodc powcr in Pi!rkinoon'~ discaw. Mowmcnt Disordcr:;, 2.J(9), pp.134·1· 1351. Andero5on, H., Ekblom, B. i!nd Krustrup, P., 200S. 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Professional players are expected to compete in 60-70 high-level matches per year. Therefore, it is virtually impossible to peak by means of classic peaking strategies, as there will be a loss of consistent performance in the preceding and ensuing weeks. It is up to the coaching staff to keep the team at a maximal stable levei for an entire season. This process is referred to as performance stabilization. i 211 218 FITNESS IN SOCCER [ FITNESS IN SOCCER Fatigue management Fatigue management 13.2 PERFORMANCE STABILIZATION At the very top level, performance stabilization can be considered at least as important as performance enhancement. It is a challenge for every soccer coach to keep the players at an appropriate leve! (around 85% of peak physical capacity) for the entire season, although periods with higher performance levels can be strategically planne<l during the season. Performance stabilisation 110% ~--------------------------- !OS% ~---------------- '= 1 ~~~-~--rL~ r.v----_ ,,...--....,, ~ 7;11 ------ '~ ~$% -100Mdo>l•pcr1s !---------------------------74)> 1 W1' B21> s&% 901' ~5% ~n: 9Sli arn oou 7Sli 70% 75% 82% S6% sm ?ali 97% ~ 87% i -_=-__:i:~~"'-~- ª~-L!~- ·-ig~ E.~- . ~.l!J,E:>..L~'!.. ~,. -~~ -~~- ~~- .!~!>..L.~- -~-11±.1.~'!. _!!_~~ _!~.!_-~U~~ ~~l Fig. 13. 1: Exampfe of a buildup in an individual sport (e.g., marathon ar cyc/e racing) as opposed to performance levei in soccer. To maintain this constant high levei, a clear strategy has to be developed to manage and manipulate a player's fatigue. We refer to this as fatigue management. Match i 219 13.3 FATIGUE MANAGEMENT As we already mentioned in the preceding chapters, performance preparedness results from the interplay betw'een the body's long-term fitness increase, which is stimulated by training, and the opposing short-term aftereffects of fatigue, also caused by training (Siff and Verkhoshansky, 1999). Specifically, it reflects the readiness of an athlete to participate in an enhanced level of training and / or excel in competition (Zatsiorsky, 1995). Fatigue is the degree to which training or match-induced stress masks the capacity to display fitness. The higher the accumulated fatigue leveis, the greater the inability to utilize the increased fitness levels. This does not imply that fitness levels have decreased but rather that they are simply masked by match- or training-induced fatigue. This also implies that, within physiologically acceptable leveis, the greater the increase in accumulated fatigue induced by training stress, the greater the potential to increase fitness levels once the player has the opportunity to recover from the stress and fatigue imposed by training or matches. Fatigue leveis should accumulate at various times of a training program to create overload and elicit adaptation. Training is nothing more than systematically disrupting homeostasis and permitting higher leveis of performance to occur. Fatigue need to be managed at tw'o levels: 1. Within a mesocycle: o Within a mesocycle, a certain specific load is imposed in each microcycle in order to generate specific fatigue, causing the body to make a specific adaptation. • Within each mesocycle, an unloading period (a lowering of volume and/ or intensity) is applied to allow fatigue to decline and let supercompensation take place. The term "regeneration" is used at times to refer to periods of extended recovery within a long-term training plan (Hackney, 1999). 2. Within a microcycle: o Recovery strategies to reduce the fatigue induced by matches as fast as possible. • Loading strategies in arder to create specific acute fatigue to elicit adaptation. o Tapering strategies to allow fatigue to decline and consequently increase preparedness for an upcoming match. Fatigue management Loadlng strategles Recovery strntegies '" ~-------+---------! -..i.- Prnparednc.1s Match Fig. 13.2: Representation ofthe fatigue management strategies in ••«•• Fitncss a microcycle Match Monday Tucsd~y Wcdo~sday Th1mdoy Friday Saturdoy Pre·matdi Fig. 13.3: Fatigue management within a microcycfe composed of three phases 220 1 FITNESS IN SOCCER FITNESS IN SOCCER [ 221 Fatigue management Fatigue management 1. Phase 1: Recovery strategies The objective in this phase is to eliminate fatigue induced by the game as rapidly andas thoroughly as possible. The training load is reduced, and recovery strategies are applied. Preparedness will decrease dueto excessive fatigue, but fitness levels remain high dueto the rnatch load. 2. Phase 2: Loading strategies In the second phase of fatigue management, the training load is high in arder to create accumulated fatigue and overload. ln this phase, the load is adapted to the physical periodization. Preparedness declines due to accumulated fatigue, whereas specific fitness increases. 3. Phase 3: Tapering strategies ln this phase of the microcycle, the main objective is to enhance the players' preparedness as much as possible. This is done by lowering the training load via reducing the volume 1vhile keeping the intensity sufficiently high (80%). 13.4 RECOVERY STRATEGIES Fatigue occurs in various forros, namely physiological, psychological, neural and hormonal. A good recovery strategy has to tackle these different forros of fatigue. Moreover, Gould and Dieffenbach (2002) demonstrated that failure to adequately recover from the stress of training induces a state of overtraining and burnout. The term under-recovery is often used in this regard. Under-recovery predisposes players to overtraining injuries during a congested fixture period where players are required to compete repeatedly within a short period (e.g., tvvo games a week) (Dupont et al., 2010). Professional soccer players are exposed to demanding competition schedules and can be easily exposed to 70 games in a single competitive season (King and Duffield, 2009). Playing competitive soccer involves eccentric work, particularly during competition, resulting in varying leveis of exercise-induced muscle damage (EIMD). This EIMD is characterized by delayed-onset muscle soreness (DOMS) (Impellizzeri et ai., 2008), decreased muscle function Uakeman et al., 2009), impaired performance (Reilly and Ekblom, 2005), and increased perceived fatigue (Twist and Eston, 2009). Many biochemical and tissue repair processes take place after a match, and the body needs rest to recover completely for the next game or training session. Although the recovery process is initiated automatically, it can be assisted by appropriate recovery strategies. The capacity to recover from training and competition is therefore an important determinant in soccer performance (Kellmann, 2002; Odetoyinbo et ai., 2009). Athletes attempt to recover from training and competition as quickly as possible, so their performances in the subsequent training session or game are not compromised by muscle soreness or reductions in physical abilities. According to Peterson (2005), "The concept of effective, regular, and varied recovery activities has become part of the Ianguage of today's smart, professional athlete." Recovery can be defined as an inter- and intra-individual multidisciplinary (physiological and psychological) process to restore the initial performance leve!. This definition implies that recovery is much more than just rest - it is a strategy that should be adapted according to the type, intensity and volume of the previous training cycle (Steinacker and Lehmann, 2002). Recovery can be defined on different leveis: 1. Within a training session or match: The amount of time between exercises (training session) or high-intensity efforts (match) 2. Within the microcycle: the amount of time between sessions on a daily basis 3. Within the mesocycle: the amount of time between longer cycles or periods of training . 4. Within the year planning: the amount of time during the off-season and m1d-season breaks. 13.4.1 Recovery between high-intensity efforts Krustrup et ai. (2006) and Mohr et ai. (2010) demonstrated that the ability to perform repeated bouts of high intensity, an important physical ability in soccer, ~s reduced toward the end of soccer games. Some research has demonstrated a positive effect of active recovery on performance in repeated sprints and on the speed of Jactate removal (Bogdanis et al., 1996). This contradicts recent research that postulates that active recovery adversely affects performance, decreases the speed of replenishment of phosphocreatine, and increases fatigue (Dupont et al., 2003; Dupont et ai., 2004; Spencer et ai., 2006; jougla et ai., 2010). On the other hand, passive recovery induces a faster re-oxygenation of myoglobin (Dupont et al., 20~4). In conclusion, it seems better to recover passively between intensive bouts dunng a match, but the recommendation that players should 1valk or stand still during and following bouts of repeated sprinting needs to be coordinated with tactical windows of opportunity. 13.4.2 Recovery post-match Several studies have demonstrated that it takes more than 72 hours to reach prematch values for physical performance and normalize muscle damage and inflammation (Andersson et al., 2008). The magnitude of match-induced fatigue, extrinsic factors (e.g., match resul~, _quality of the opponent, match location, playing surface, envirorunental cond1tions) and/ or intrinsic factors (e.g., training status, age, sex, muscle fiber typology), could influence the time course of recovery (Nédélec et al. 2012). Severa! post-match recovery interventions have been suggested to _e~ha~ce performance (Barnett, 2006). These recovery strategies are broadly class1fied 1nto two categories (Bompa, 1999): active and passive recovery. Active recovery strategies include cycling, jogging, aqua-jogging, and deep-water running,. f~llowed _by stretching exercises. These interventions are regularly used after tra1n1ng sess1ons and matches in professional soccer (Dabedo et al., 2004). ln particular, when n:atches are played on a weekly or twice-weekly basis, focus is placed on accele:ating t~1e recovery and consequently the regeneration processes. This commences 1mmed1ately after the match by using nutritional strategies to replenish glycogen stores and drinking water or carbohydrate beverages to restore fluid balance. With the next competitive match 3-7 days away, a recovery training session is often planned the next day as well. It is still unclear whether immediate post-match recovery offers additional benefits when compared to a traditional next-day recovery. A cool down after a tough training session often feels good, and the psychological relief of some 222 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management Fatigue management easy jogging, stretching and discussing the session with teammates can work wonders for the mental well-being of players. However, a cool down after a game or during bad weather conditions is often impractical and can put additional psychological and physiological stress on the players. Is it really necessary to start active recovery sessions immediately after the game, or can this wait until the next day? Dawson and colleagues (2005) investigated four types of immediate post-match recoveries: 1. Control (i.e., no proactive recovery): The players were instructed to perform no recovery procedures other than eating (fruit), drinking (water and soft drinks), and showering. 2. Stretching: The players were led through 15 minutes of gentle static stretching of the legs and back, involving two or three reps of 30s-held stretches across several muscle groups and joints. 3. Pool walking: The players were taken through 15 minutes of easy walking (moving forwards, backwards and sideways) in the shallow end of a 28ºC swimming pool. 4. Hot/Cold cycling: The players altemated behveen standing in a hot (- 45ºC) shower for two minutes and standing waist deep in icy water (-12ºC) for one minute, repeated until five hot and four cold exposures had been completed. Additional ice was added to the cold water as required to maintain a constant temperature. The authors concluded that performing any forro of immediate post-match recovery did not significantly enhance the recovery of muscle soreness, flexibility and po\ver within the first 48 hours follO'vving a game when compared to just performing a "next-day" recovery training session. 13.4.3 Types of recovery 13.4.3.1 Allowing sufficient recovery time Soccer governing bodies such as FIFA and UEFA should consider the physiological and mental consequences for players in periods of congested fixtures and lighten the physiological strain as much as possible by mandating a minimum of 72 hours behveen competitive matches (Reilly, 2005; Ispirlidis, 2008). A soccer match increases the levels of oxidative stress and muscle damage throughout a 72-hour period (Andersson, 2010; Ascensao, 2008; Ispirlidis, 2008). The recovery time between two matches in a week seems sufficient to maintain levels of physical performance, but it is not long enough to maintain a low injury rate. Adequate recovery strategies are necessary to maintain a low injury rate among soccer players during periods of congested match fixtures (Dupont, 2010). 13.4.3.2 Active recovery Active recovery (Baldari et al., 2004; Tessitore et al., 2007): • reduces muscle soreness (Reilly, 1998) • increases muscle-damage recovery (Gill et al., 2006) 0 prevents venous pooling in the muscles after maximal effort (This can cause dizziness and sometimes fainting. When an athlete or player faints or collapses after maximal efforts (or vvhen crossing the finish line), the most common cause is stopping so suddenly that the blood pools in the extremities (usually the legs), depriving the brain of oxygen for a moment. Typically, this is referred to as postural hypotension (Crisafulli et al., 2006).) • restares metabolic perturbations (Bangsbo et al., 1994; Bogdanis et al., 1996) • increases lactate clearance. (Maximum clearance occurred at active recovery close to the lactate threshold (Menzies et al., 2010). However, for team sports like soccer, lactate removal is not a determining factor, as matches are generally 3-9 days apart.) ./ Running activities Reilly and Rigby (2002) investigated the effect of post-match active recovery in soccer and reported that muscle soreness disappeared hvo days after the match in the active post-match recovery group. They found that amateur soccer players vvho did an immediate post-n1atch recovery comprised of some jogging, stretching and a leg-muscle "shakedown" (by a partner) for 12 minutes had lower muscle soreness ratings and \vere closer to their pre-match jump and sprint performances both 24 and 48 hours after the match \Vhen compared to a group of players \Vho did not perform any recovery. ln another interesting study by Rey et al. (2012), the effect of immediate post-training active- and passive-recovery interventions on anaerobic performance and lower-limb flexibility in professional soccer players \VaS investigated. The active recovery consisted of 20 minutes of low-intensity exercises, incluM ding 12 minutes of submaximal running at 65% of maximum aerobic speed and 8 minutes of static stretching, involving 3 bilateral repeats of 30s-held stretches to the hamstring, quadriceps, gastrocnemius, and adductor muscles. The investigators suggest that post-training active-recovery intervention may help in restoring counter movement jump performance, but this does not represent performance i 223 224 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management Fatigue management enhancements in the 20m sprint, Balsom agility test, and lower-limb flexibility for professional soccer players. Running activities followed by static stretching could reduce delayed onset muscle soreness. However, the research is inconclusive about the effects of low-intensity running exercises on recovery. ./ Pool sessions Exercising in water has been suggested by some researchers (Dowzer and Reilly, 1998; Oda et al., 1999; Suzuki et al., 2004). The advantages of running in water {aquajogging ar deep-water running) over normal running are numerous: • It avoids excessive eccentric actions, especially in deep water. 0 It naturally massages the muscles (via the water turbulence). • It reduces mechanical load on the joints. • It aids recovery from musculoskeletal fatigue. • It increases the physiological and psychological indices of relaxation. ../ Stretching Few publications have investigated the effect of stretching on recovery. Many coaches still believe that stretching post-exercise will increase blood flow. Research demonstrates clearly that stretching after a workout does not help and may in fact discourage blood flow (Poole et al. 1997, Mika et al. 2007). Montgomery et al. (2008) postulated that static stretching after exercise could be recommended as a recovery strategy in order to prevent delayed onset muscle soreness and improve range of motion. Contradicted findings were published by Wessel and Wan (1994) who found that stretching before or after exercise did not improve DOMS. Coaches should be careful in applying stretching after intensive training or match play. This causes exercise-induced muscle damage, and post-exercise stretching can potentially cause further trauma. ln conclusion, serious stretching after an intensive training or game is contraindicated for recovery. 13.4.3.3 Passive recovery ../ Cold-water immersion (CWI) These are the possible mechanisms of post-exercise cooling: • It reduces pain and swelling, having an anti-inflammatory effect and reducing the potential for DOMS. 0 It causes vaso-constriction, which increases blood flow and metabolic transportation post-exercise. Additionally, CWI rnay decrease nerve transmission speed (Wilcock, 2006) and alter the receptor threshold, leading to decreased pain perception. There may also be a psychological mechanism whereby the body feels more "awake" and perceives a reduced sensation of fatigue after exercise (Cochrane, 2004). ln conclusion, a cold-water bath after a match will not cause any harm, and it rnay likely boost recovery and constitute a good recovery strategy for those with a "marginal gains" philosophy. Poppendieck et al. (2013) concluded in theír meta-ana- lysis that the expected percentage improvements in performance recovery from post-exercise cooling are large enough to be relevant for competitive athletes. ln particular, for whole-body CWI, cooling-induced improvements of S~'o ar more can be expected. These results are similar to those of Leeder et aL (2011) and Bleakley et al. (2012), who identified positive effects of cooling on the reduction of muscle soreness, although they found only small or unclear effects on performance indices. Halson (2011) postulated that no gold standard exists for CWI as regards water temperature, immersion depth, and duration. Based on the available literature, the recommendation is for a whole-body immersion lasting 10-20 minutes in a water temperature of 10-15ºC (Halson, 2011). ../ Compression gannents Compression garments (CGs), such as compression socks, were originally used ín clinicai settings. While the benefits of CGs include being relatively cheap, easy to use, and non-invasive, the current literature indicates that wearing these garments has limited physiological or performance effects, although reports of detrimental effects are rare (Macrae, 2011). Various research has suggested that CGs increase the removal of cellular debris, moderate the formation of edema associated with EIMD, attenuate muscle oscillation, change sub-maximal oxygen usage during exercise, alleviate swelling, and reduce perceived muscle soreness during post-exercise recovery. They have also been suggested to offer mechanical support (dynamic casting effect) to the muscle, allovving faster recovery following damaging exercise (Kraemer et al., 2001). Recent research pointed out that a whole-body compression garment worn during the 24-hour recovery period following an intense heavy-resistance training \Vorkout enhances various psychological, physiological, and performance markers of recovery, when compared with non-compressive control garment conditions. The use of compression appears to help in the recovery process after an intense heavy-resistance training workout in men and women (Kraemer et al., 2010). This was confirmed by Jakeman et al. (2010) when they concluded that compression clothing is an effective recovery strategy following EIMD. A recent review by MacRae et al. (2011) concluded that the temptation to take findings from one cohort (e.g., untrained people) ar exercise type (e.g., jumping) and apply them to other cohorts and exercise types (e.g., untrained people and prolonged running) is questionable. The garment type, the applied pressure, and the duration of wear often differ, complicating the matter further. Hence, more research is required before practical recommendations can be made. ln conclusion, wearing CGs might support recovery and reduce DOMS, and no detrimental effects have been reported. Players could be encouraged to use compression socks during recovery or taper, particularly when travelling by car or plane. ./ Sleep The effect of sleep on athletic performance has become a topic of great interest because of the growing body of scientific evidence demonstrating a direct relationship between criticai sleep factors (sleep length, sleep quality; and circadian sleep phase) and human performance (Samuels, 2008). Research speculates that sleep supports improvements in sport performance, because during phases of deep sleep, growth hormone is released. Growth hormone stimulates muscle growth i 22s 226 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management Fatigue management and repair, prometes bone building, and helps athletes recover. On the other hand, a lack of sleep has been associated with under-recovery, alterations in mood and motivation, anda negative effect on athletic performance. Sleep deprivation: • reduces the ability to store glycogen • reduces decision-making quality and reflexes • increases stress hormones (cortisol) 0 negatively affects recovery. (Skein et al. (2013) examined the effects of overnight sleep deprivation on recovery following competitive rugby league matches. They found that sleep deprivation negatively affects recovery, specifically impairing CMJ distance and cognitive function.) • lowers leveis of growth hormone needed to help repair the body For optimal performance, players should be encouraged to maximize their sleep in a dark, calm, relaxing and fresh atmosphere during the week preceding competition (Halson, 2008). This was confirmed by Mah et al. (2011) who investigated measures of basketball performance after sleep extension. Participants were first asked to follow their habitual sleep period (e.g., an eight-hour sleep period). They were then subsequently asked to voluntarily extend their total sleep time, with a minimum goal of a ten-hour sleep period for a five-to-seven-week period. The participants were found by all the measures to have enhanced basketball performance after the habitual sleep extension. Total sleep times increased by approximately two hours, and participants were shown to sprint faster and have greater shooting accuracy when compared to their baseline performance. Alertness also improved-as did mood, weariness, and fatigue-leading the investigators to conclude that optimizing sleep need (i.e., reaching sleep satiation) was likely to have a positive impact on measured athletic performance. Although there is an individual variation in the amount of sleep required for essential recovery processes, the adaptive sleep range is approximately 8-10 hours (Bompa, 2009; Calder, 2003). Athletes should be encouraged to take a 20-minute nap (often called a "po\ver nap") during the day (Postolache and Oren, 2005). Naps should be scheduled in. the mid-to-late afternoon after 2pm but not after 4pm, because this can result in sleep inertia (Samuels, 2008). Naps can equate to an hour of "extra" nighttime sleep (Horne, 2011). Recommendations for females aged 18+ and males aged 19+ (Samuels, 2008): 0 Ensure a comfortable sleep environment when travelling and competing. 0 Monitor for competition stress and aruciet)' insomnia. 0 Observe sleep to identify sleep disorders. • Maintain a regular sleeping and napping routine. • Monitor for a delayed sleep phase, such as difficult;r falling asleep and waking up for school. • Get early-morning light exposure for 30 minutes daily. • Maintain reliable nutrition routines. Breakfast is the most important meal of the day. • Focus on reducing sleep debt. Get 56-70 hours of sleep per week. • Do not train if unrested and sleep deprived. • Avoid technology (e.g., PCs, smartphones, tablets) before bed. ./ Psychological strategies Performance in soccer is a result of a complex synergistic interaction of technical, tactical, physiological, psychological, environmental, and social factors. ln this regard, the athlete has been described as a "psychosocio-physiological entit;r" (Kenttã and Hassmén, 2002). Soccer players currently face more social pressure than ever before, and they are exposed to increased media demands, sponsorship requirements, and information overload (Botterill and Wilson, 2002). Mental recovery is a vital part of the recovery process (Maughan, 1998). Mental-recovery strategies may include debriefing, emotional recovery, mental toughness skills, and relaxation techniques. A successful debriefing enables both the coach and the player to evaluate game performance and identify specific areas in need of change. Moreover, goals can be reframed, with realistic goals being set for the next training session or match. Venter (2012) investigated the perceptions of team athletes on the importance of recovery modalities. The results from this study demonstrated that team players do perceive psychosocial aspects to be among the most important recovecy modalities. Sport psychologists could assist coaches with effective debriefing procedures after matches to aid mental and emotional recovecy, as well as facilitating team cohesion to address aspects of psychosocial recovecy. There may be a need to educate players and coaches in regard to recovecy modalities, and this might also assist with psychosocial recovery. Effective strategies: o Organize a debriefing after each game. • Set realistic goals. o Social networks can help players <leal with the problems, disappointments, joys and stresses of life (Quinn and Fallon, 1999). • Appoint players carefully for media demands and sponsor needs. • Reframe goals if long-term goals look difficult to reach. o Give players space to develop effective pre- and post-match strategies. o Social support may increase performance (Freeman and Rees, 2008). • Try to protect players from the negative impact of stressors (Botterill and Wilson, 2002; Rees and Hardy, 2004). o Encourage players to create a playlist of music they enjoy that generates a range of moods and atmospheres soas to produce a stimulating or calming effect (Calder, 2000). • Do not force players into post-match recovery strategies that are perceived as stressful. o Encourage friends and teammates to provide listening and emotional support; challenge evaluation of attitudes, values and feelings; express appreciation; and motivate other players to greater excitement and involvement (Barefield and McCallister, 1997). lt can be concluded that relaxation strategies-such as meditation, music, muscle relaxation, visualization, breathing exercises, music, and floatation-are regularly used, yet the effects of these strategies have been barely investigated. i 221 228 1 FITN ESS 1N SOCCER Fatigue management ./ Nutrition and hydration (See chapter 4) Alcohol consumption occurs regularly in many team sports, typically as part of a post-match celebration or as an escape from the realization of failure (Maughan, 2006). This behavior is widespread and often seen as an acceptable part of team culture (Barnes et al., 2012). O'Brien et al. (2005) studied a student population and found higher rates of hazardous drinking in elite sportspeople (O'Brien et al., 2005). On the other hand, it has been reported that sports participation might delay drinking debut in youngsters (Hellandsjo Bu et al., 2002). Barnes et al. (2010) concluded that alcohol magnifies the severity of skeletal muscle injury and therefore delays recovery of strength over the following 24-hour period, suggesting that participants of sports involving intense eccentric muscular work should be encouraged to avoid alcohol intake in the post-event period when optimal recovery is required. This was confirmed a few years later by the sarne research group after 80 minutes of a simulated rugby game. The consumption of lg of alcohol per kilogram ofbody mass had a negative impact on lower-body vertical power output. ./ Massage There is limited scientific evidence showing that massage might assist in recovery strategies (Monedero and Dorme, 2000). Recent research by Jakeman et al. (2010) reported that a combined treatment of a 30-minute manual massage and a 12-hour lower-limb compression significantly decreased perceived soreness at 48 and'72 hours after plyometric exercise when compared to passive recovery or compression alone. This was confirmed by Hilbert et al. (2003) when they reported moderated muscle-soreness ratings 48 hours after exercise when a massage was administered 2 hours after eccentric exercise. Massage should be carefully administered after intensive training or match play, since massage can possibly counter the natural recovery process of the body. Some researchers even suggest that a massage should not be applied after training ora match because post-exercise massage could cause further trauma when training or match play has caused EIMD (Barnett, 2006). Moreover, it seems that the training level of the therapist affects the effectiveness of massage (Moraska, 2007). ./ Cortisol and the autonomic nervous system Cortisol, or hydrocortisone, is a steroid hormone produced by the adrenal glands in response to a stressar. A stressar is any potential source that places a physical, mental, or emotional strain on the body or mind during a demanding circumstance. When faced with a stressar, the brain triggers a cascade of hormones that ultimately leads to the release of cortisol (sympathetic nervous system). This hormone is responsible for physically preparing the body to <leal with whatever situation has been encountered. This physiological reaction is often referred to as the "fight-or~ight" response. This term applied in a much more literal sense during prehistoric times. An encounter with a rival looking for a fight ora hungry predator Iooking for a meal demanded the physical preparation necessary to endure the conflict or run from the danger. Since the evolution of civilization, however, the need to fight or run for survival is a rare occurrence. Typical stressors today include school exams, deadlines at work, and troubles with relationships. Although humanity's social b~haviors hav~ rapidly evolved, the reaction to stress remains the sarne. Physiolog1cal changes induced by the stress response still include a temporary elevation of FITNESS IN SOCCER Fatigue management heart rate and an increase in fuel supply to the muscles. At times, this reaction to a stressful situation can be less than ideal. For instance, consider standing in front of a crowd to give a speech with a pounding heart and sweaty palms. For a stressor such as exercise, though, these physical changes are optimal for physical exertion. Cortisol plays a necessary role in performance during exercise. The increase in heart rate and the fuel supply to working muscles provides the necessary adaptations to perform at a high level. After exercise has ended, however, a sufficient period for recovery is necessary to retum to baseline hormonal levels. Adequate time allows the clearance of elevated leveis of circulating cortisol, while insufficient time leads to chronically elevated leveis. If cortisol leveis remain elevated for a prolonged period: a number of adverse side effects will occur. These include slower recovery rates, immune system suppression, gastrointestinal problems, lower testosterone leveis, weight gain, cardiovascular disease, insomnia, fatigue, psychological stress, depression, increased blood pressure, reduced serotonin levels, memory disorders, decreased bone formation, blood sugar imbalance, fertility problems, and more. While these side effects are numerous and undesirable, they can be avoided with the practice of appropriate lifestyle habits. Proper recovery from exercise requires a multi-factorial approach. Healthy lifestyle habits strongly influence the time needed to balance disrupted hormone leveis. A timely recove1y can be achieved with adequate sleep, proper nutrition, and the practice of various other beneficial lifestyle habits. During sleep, a natural balance of circulating hormones occurs. A good night's rest results in a sleep-induced decline of elevated cortisol levels, These rise even further, however, with insufficient sleep. Seven and a half hours of sleep per night may be considered a sufficient amount, but nine hours is optimal. Proper nutrition provides all of the essential vitamins and minerais necessary for bodily functions. Nutritional factors will also strongly affect hormonal leveis. Maximizing foods like fruits, vegetables, and nuts while minimizing foods like trans fats, refined carbohydrates, and sugar will result in a decline of circulating cortisol. Conversely, poor dietary habits will result in an increase in the leveis of this hormone. The practice of many other various habits will also influence leveis of circulating cortisol. Severa! parameters will reduce cortisol levels and therefore decrease the time needed for recovery. These factors include proper hydration, massage, meditation, deep-breathing techniques, laughter, music therapy, reduction of psychological and emotional stress, and consumption of whole foods such as fruits, vegetables, beans, nuts, seeds, and wild fish. Likewise, several factors increase cortisol levels, extending the time necessary for recovery. These factors include alcohol consumption, caffeine intake, severe caloric restriction, a low-fiber diet, the consumption of insufficient micronutrients and antioxidants, a sedentary lifestyle, and being overweight. Cortisol and sympathetic dominance is a necessary component of exercise, but prolonged elevated levels can be detrimental to performance. While the role this hormone plays in exercise is elaborate and complex, the necessary methods for recovery are simple. Adequate sleep, proper nutrition, and the practice of good lifestyle habits will result in improved recovery from exercise and an increase in performance. i 229 230 1 Fl:NESS IN SOCCER Fatigue management FITNESS IN SOCCER Fatigue management 13.4.3.4 lndívidua/ization Since various studies on the effectiveness of recovery strategies show a high inter-individual variability, coaches should utilize different recovery strategies with different players. Coaches should also consider appropriate diets, rehydration, and a controlled lifestyle, and this may be a sufficient recovery intervention for young elite athletes (Tessitore et al., 2007). It may be even advisable to customize recovery interventions individually based on the requirements and preferences of players. After a match, emotional and mental states can increase or decrease fatigue. One player might want togo to the forest or park for a recovery session to clear his head, while another player might perceive this as an additional source of frustration, exacerbating the psychological fatigue. It seems essential to customize recovery methods according to gender, especially given the effects of gender on the physiological responses during exerdse and the post-exercise recovery period, so as to maximize the processes of physiological recovery while minimizing the risks of injury in female athletes (Hausswirth and Le Meur, 2011). Venter (2012) examined how elite team athletes perceive the importance of various recovery modalities. Differences between men and women, players frorn various team sports, and different leveis of participation were determined. Recovery modalities that were rated as important by all players-regardless of gender, type of sport, or levei of participation-were sleep, fluid replacement, and socializing with friends. Gender could play a role in how the importance of recovery rnodalities was perceived. Men rated anice bath and supplernents as significantly more important than women, while women rated discussions with their teammates and coaches after training and matches as significantly more important than men. 13.4.4 Recovery strategies: Conclusion The recovery phase must be considered as an inherent component of the training process. It must therefore be granted the sarne degree of attention in its programming and management as the exercise sessions themselves (Hausswirth and Le Meur, 2011). Given the importance of improving how athletes feel, combined recovery strategies could be used after intense soccer match play to help perceived recovery (Kinugasa and Kílding, 2009). Recommendations: • Replenish glycogen stores immediately after a match (intake of carbohydrates). • Consume proteins to assist muscle regeneration. • Don't drink alcohol before or after a match. • Warm up properly, because this will decrease post-match DOMS. • Restore fluid balance. • Do not use massage. • Replenish electrolytes. • Sleep a minimum of 10 hours for each of the two days following a match (sleep extension). • Take a daily nap of 25 minutes after lunch (between lpm and 4pm). • Avoid any eccentric work in the two days following the match. • Avoid explosive actions, such as sprinting or shooting drills, in the 48 hours after a match. o Organize a debriefing and set realistic goals after the match. 0 Organize whole-body, cold-water immersion lasting 10-20 minutes ata water temperature of 10-lSºC. (This may be after the game or the day after.) • Avoid stressful situations. ° Customize recovery and don't oblige players to participate in recovery strategies that could be perceived as stressful. • Explain the use of the recovery strategies. • Focus on mental recovery after the game. ln conclusion, post-match recovery can help prevent muscle soreness and therefore the quality of subsequent training. However, passive post-match recovery strategies-such as mental recovery, social support, nutrition, hydration and adequate sleep-are probably the most irnportant recovery strategies for the hours directly following a game. Active recovery strategies are best planned for the following day, because no differences have been found when using immediate post-match active recovery. Coaches should also be aware that rest and mental recovery are important. Forcing players to come to the ground through busy traffic, or forcing skeptical players to undergo cold-water immersion or contrast baths, will probably frustrate adequate recovery because it increases mental stress, and this will subsequently jeopardize recovery. Short-term rccovcry Process Duration Phosphocreatine stores 3-5 min. The replenishment of CP stores is an oxygen dependent processes (Bonen et ai., 1978) Breakdown and processing of lactate 1-3 hours. The half-life period is approximately 15 min. Awide range of lactate e!imination constants (expressed as half-life period: 9.2-18.2 min) has been demonstrated in cyclists after exhaustive exercise. This supports the hypothesis of inter-individua! variation in lactate kinetics. (Frnncaux et a!., 1989) Table 13.1: Short-tenn recovery (< 6 hours). Recovery between 6 and 36 hours Process Duration Glycogen compensation 24-36h Normalization and replenishment of electrolyte concentrn!ions (N, Ka) 6h Buildup of contractile proteins 12-48h Tab/e 13.2: Recovery between 6 and 36 hours. 1 231 232 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management Fatigue management RECOVERY >48H Process Duration Replenishment of musc!e enzymes 48-60h Rebuilding of protein structures, including mitochondria 48-72h Supercompensation of glycogen reserves 48-72h Replenishing electro!ytes (Mg, Fe) 48-72h Replenishment of hormones catecho!amine resynthesis 48-72h Cortisol resynthesis 3-5 days Replenishing of glycogen stores Pi eh li (197 4) investigated the reptenishment of glycogen stores after exercise. During the first five hours, there was a marked storage of glycogen in the muscle that was re!ated to the carbohydrate intake, but pre-exercise concentrations of muscle glycogen were first observed after 46 hours. The increase in glycogen occurred in both fiber types, but the fast twitch fiber replenished their g!ycogen somewhat faster than the slow twitch fibers, suggesting a higher g!ycogen synthetase activity. New production of structura! proteins {enzymes, mitochondria, binding support tissue) 13.5.2 Heart Rate Variability (HRV) It has been proposed that the cardiac autonomic nervous system-assessed nonin- vasively via exercise heart rate (HRex), heart rate recovery (HRR) or heart rate variability (HRV) (Buchheit et al., 2012}-may provide useful information regarding functional adaptations to a given training stimulus. HRV recordings have been shovvn to reflect acute fatigue following exercise (Mourot et al., 2004) and used to make inferences about appropriate training periodization (Kiviniemi et al., 2007}. The usefulness of a marker to assess physiological adaptation to training ideally requires it to be easy to administer, so frequent monitoring will be possible with minimal inconvenience to the athlete (Borresen and Lamber, 2008). Studies monitoring daily morning HRV at rest (Plews et al., 2012; Sartor et al., 2013) or post-exercise (Buchheit et al., 2012) have used protocols that require recordings in excess of five minutes. This may not be practical in a team sport environment. It has been suggested that ECG recordings as short as 10 seconds can accurately predict cardiac vagai tone (Hamilton et al, 2004). This therefore opens the doar for shorter, more practical HR recordings, which could then be used to access daily HRV in a team environment. 13.5.2.1 Guidelines for col/ection days to weeks Tabfe 13.3: Recovery > 48 hours. 13.5 MONITORING FATIGUE ANO RECOVERY IN SOCCER 13.5.1 lntroduction The implementation of a successful training program in soccer requires an appropriate training stimulus relative to the physical capabilities of the player, coupled with adequate recovery periods. Failure to maintain this equilibrium can increase injury risk and lead to overtraining (Kuipers and Keizer, 1988). Therefore, in highly trained soccer players subjected to high training loads, any methods likely to improve the knoi;vledge of a player's training status are of great interest to coaches. Multiple methods for monitoring load and status have been suggested, but their invasive (e.g., blood markers) (Heisterberg et al., 2013) and/ or exhaustive (e.g., maximal tests) (Meeusen et al., 2006) nature makes them difficult to monitor frequently in a team sport environment. More recently, a number of more practical testing methods have been suggested and researched, such as heart rate variability (HRV), monitoring of neuromuscular fatigue through jump tests, and the use of subjective questionnaires. This chapter will therefore detail various practical methods for monitoring fatigue and recovery, outline protocols for data collection in a squad environment, and provide information on various analysis methods. Finally, it will offer the reader some steps and information on developing a player-monitoring system that can be used to visualize data and provide the coach or sports scientist with an overview of a player's training status. l Day-to-day variation in HRV values is high because of a number of environmental factors, such as noise, temperature, light and so on (TaskForce, 1996). The lack of sensitivity ofHRV measures to detect fatigue may at times be caused by the relative "errar" of these recordings (AI Haddad et al., 2011), and these factors most likely account for the large discrepancy between studies. Thus, a consensus on the most valid and reliable HRV índex and collection method needs to be established for consistent research methodology and data collection in a practical environment. As is shown in the literature, HRV assessments can be highly sensitive to physiological and environmental changes. The physiological changes are what we want to monitor, so it is therefore very important to limit the number of externai factors that can lead to inaccurate, unreliable results. In arder to gain the most accurate and therefore most useful results, it is vital to be consistent in your measurement protocol. One of the most important factors in gaining accurate results is the timing of the measurement. Research and product guidelines from companies offering HRV-assessment products (e.g., OmegaWave, iThlete, etc.) suggest that the most accurate time for assessment of ANS status is first thing in a morning upon waking. During sleep, the parasympathetic branch of the ANS is dominant, repairing and rebuilding muscles and replenishing fuel stores. Thus, after a night of rest is the optimum time for HRV assessment. However, this may not be the most practical method in a team environment. It requires each player to have access to equipment at home and trust in the players to complete this assessment correctly away from coaching and medical staff. Another assessment protocol proposed by Martin Buchheit is the 5' -5' test. This involves 5 minutes of running ata submaximal pace (9 km/h) folloi;ved by 5 minutes of recovery. This test allows for assessment of HRex during the 5-min run, HRR during the first 60s of recovery and post-exercise HRV from the final 3 minutes of recovery. The rationale behind this method of assessment is the ability to assess multiple HR indices all at once and its ability to eliminate environmental stressors that are apparent during resting HRV assessments. While this protocol is time con- 1 233 234 1 FITNESS IN SOCCER 1 . 235 Fatigue management FITNESS IN SOCCER Fatigue management ./ HRV Indices Using the R-R interval gained from the ECG, a number of time-domain and frequency-domain methods can be used for analysis (mathematical calculations used to assess HRV from R-R intervals). Task-Force (1996) suggests the variety of time-domain measures of HRV is not important, because many of the measures correlate closely with others. However, the Ln rMSSD is suggested as the preferred index for assessing short-term components of HRV. Ln rMSSD is a mathematical calculation behveen R-R intervals and stands for "the natural logarithm of the square root of the mean sum of the squared differences behveen R-R intervals." Ln rMSSD has been shown to be the most reliable HRV index for short-term recordings, and it is used by manufacturers of HRV-assessment products for a number of reasons: • Breathing frequency, unlike other spectral índices of HRV, does not signi.ficantly influence Ln rMSSD and is therefore more suited to ambulatory measures. • Ln rMSSD can capture leveis of parasympathetic activity over a short time frame, which is more convenient for athletes \Vho have limited time to acquire a reading. suming, rnaking it less practical for daily monitoring of fatigue and recovecy in soccer, it could be used on a weekly, monthly or post-training-phase basis, and it has been shown to correlate well with fitness- and drill-based running performance (Buchheit et al., 2012). A more practical method of assessing HRV may be a morning resting reading conducted on arrival at the training ground. This allows for a quick and reliable assessment on a daily basis under the supervision of coaching and medical staff. When using this protocol, it is important to educate the players about their morning routines. Players must consume no liquids other than water, particularly no energy drinks or coffee. They must also refrain from any strenuous activity and not consume any food until after the assessment. Further details and an example of this protocol will be set out later in the chapter. 13.5.2.2 Analysis Once a valid and reliable assessment protocol has been set out and data has been collected, the next important step is data analysis. With modem technology like iThlete and OmegaWave, all of the analysis is dane for you. You simply perform the ECG recording and are given a HRV score. Some statistical analysis on your "readiness" to train is even provided using rolling averages and worthwhile-change statistics. However, for a sports scientist, it is important to understand the process behind these numbers. The first step in the analysis of HRV is obtaining high-quality ECG tracings under stable, controlled conditions. ln a practical environment, this will usually be completed via HR telemetry. The second step is the recognition of the QRS complex (Figure 13.4A). Peak detection is often performed with commercially available sofhvare. An algorithm is then used (Beckers et al., 1999) for threshold detection. The result is a discrete, unevenly spaced time event series: the tachogram obtained from the ECG. It is crucial that these signals are corrected for abnormal and missed beats before processing (Aubert and Ramaekers, 1999; Pumprla et al., 2002). After this step, an R-R interval (ali intervals behveen adjacent QRS complexes resulting from sinus nade depolarizations, often called a normal-to-normal (N-N) interval) can be obtained (Figure 13.4B). ./ Daily vs. Weekly Analysis As previously stated, day-to-day variation in HRV can be high dueto environmental noise. This makes the analysis of daily changes difficult to interpret. Research has proposed that when HRV is used to assess changes in both negative and positive adaptation, both weekly and seven-day rolling averages may provide better methodological validity than values taken on a single day. For example, Plews et al. (2013) found that when HRV data points were averaged over a week, a meaningful representation of training status was apparent in an NFOR (non-functional over-reaching) elite triathlete (i.e., worthwhile reductions in weekly-averaged HRV were observed only during the period of NFOR). Comparatively, when single day values were used for analysis, the HRV data were misleading (i.e., worthwhile reductions in HRV indicative of NFOR occurred when the athlete was training and performing effectively). This suggests that averaged morning resting HRV data provides a more consistent representation of actual changes in an athlete's autonomic balance with training when compared with a single isolated value. A 1 1! B Fig. 13.4: A) Hearl rate QRS complex obtained from ECG. B) Example of hearl rate R-R intervaf. 1 1 f ;q! '.~~--, ./ Weekly Coefficient of Variation (CV) An innovative method of assessment proposed by Plews et al. (2013) is a weekly rolling coefficient of variation (CV). The authors found a reduction in the day-today variability of HRV, in conjunction with rolling average HRV, in an athlete that was diagnosed with NFOR. The authors therefore suggested weekly rolling CV may provide a more complete measure for diagnosing NFOR, as it is still unclear whether HRV should be expected to increase ar decrease in the case of overtraining (OT). The use of rolling CV would be therefore applicable irrespective of the trend towards parasympathetic ar sympathetic dominance and the stage of NFOR ar OT. 236 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management 1237 Fatigue management ./ HRV to HR Ratio A further method of HRV analysis that was suggested by Plews et al., (2013) is the Ln rMSSD to R-R interval ratio. They propose that a common misconception made by sports practitioners using HRV to assess ANS status is that there is a direct linear relationship between the vagal-related indices of HRV and the parasympathetic influence on heart rate (HR). ln reality, however, the relationship is quadratic (Goldberger et ai., 1994). This means that at both low (high HR) and high (low HR) levels of vagal tone, vagal-related HRV indices are reduced. This is an important consideration for practitioners using HRV to assess training status in elite athletes, who typically have a low resting HR, undergo high training loads, and are therefore prone to saturation (e.g., decrease in HRV and decrease in HR) (Kiviniemi et al., 2004). For example, during the different phases/loads of training, reductions in HRV can occur, "theoretically" indicating ANS stress. However, this trend should only be interpreted in light of the respective changes in resting HR to assess whether this decrease can be the result of the saturation phenomenon or not. This can be achieved by using the HRV to HR ratio, which simultaneously considers changes in both vagai tone (HR) and vagal modulation (HRV). However, research has shown that individual players can display very different HRV to HR ratios when they are fatigued or in an optimal state (Plews et al., 2013; Fitzpatrick et al., unpublished). 110 r=-0.60 {-0.90;-0.fi4) 100 ~ ~ • '" .. ~ .. 00 .~, 70 r=-0.17 (-0.4!1;UH) "!ow<eire!atod" 00 ' ',, "' 10• ~ ~ • ~ • .., r:.(l,59 (-0.79:-0.30) •tricar'" 00 110 t= ~ > ~ 00 70 00 00 40 . ... ,.., -- ' 00 ' ''-., ',,_ •, .. ~ r=.(l.75 (-0 61;-0.~6) • 'L~nr'" " 70 -0.42 ·~=~~~)º" 100 00 'HR (tioot.mlrr') 00 100 40 50 00 70 00 00 This has important implications for practitioners working in soccer, where data may be analyzed as a group and the conceptions of what is optimal may be applied to the group as a whole. Furthermore, the optimal relationship between HRV and RHR is likely to be individual (i.e., correlated, low-correlated or saturated [Kiviniemi et al., 2004]). This implies that longitudinal monitoring and an understanding of an individual player's response to training and competition (HRV to HR "fingerprint") is needed before this relationship can be useful enough to assist with training prescription and act as a possible predictor of overtraining. 13.5.2.3 HRV Summary In summary, reductions in HRV may be associated with fatigue in soccer players. However, the conclusions from past literature suggest isolated HRV values should be viewed with caution. We suggest the use of both the HRV rolling \veekly average and HRV-to-HR ratio to correctly interpret fatigue, ora "readiness to perform," in soccer players. (i.e., Worthwhile reductions in HRV with concurrent increases in the HRV to HR ratio are more indicative of fatigue, with decreases in both possibly indicating readiness to perform.) Furthermore, the optimal relationship between HRV and HR for training and performance alone is likely to be individual. This implies that longitudinal monitoring and an understanding of a particular athlete's response to training and competition is required for effective monitoring. 13.5.3 Monitoring Neuromuscular Fatigue ~ ....,~ • •• ,.!' 70 " . , .. -0.37 (-0.64;-0.03) ·1ow-o;... li1:,,d· .. .,.,.. .... 00 ,, ''· '',, Figure 13.5 shows HRV to HR profiles for six players in the sarne squad, all of who completed the sarne six-week preseason training program. All players show distinctly different profiles, despite the fact that ali players coped well with the demands of training, as is evident in the stable levels of HRV (-0.01 (-0.11; 0.09) AU/ day) and wellness (-0.02 (- 0.06; 0.03) AU / day) throughout the training period 100 HR(IX:nlltli"'f 1 ) Fig. 13.5: HRV to HR profi/es for six different players who ai/ followed lhe sarne training program over a six-week preseason training period (Fitzpatrick et ai., unpublished). Measures of neuromuscular function are often used to assess recovery after soccer training or match play (Magalhães et ai., 2010) because of their greater ability to monitor low-frequency fatigue compared with other indirect markers. Measures of neuromuscular function include various jump tests (e.g., countermovement jump, squat jump), sprint performance, and isokinetic dynamometry. Jump procedures are popular due to their replication of the stretch-shortening capabilities of the lower-limb musculature and the ability to evaluate fatigue (Komi, 2000). Moreover, jump measures are ideal for a soccer environment because they are noninvasive, easy to administer, easy to interpret, and cause minimal additional fatigue (Twist and Highton, 2013). While some research has questioned the sensitivity of jump procedures in assessing neuromuscular fatigue in tearn sports (Cormack et al., 2008), others have found it to detect impaired muscle function in soccer players following match play (Magalhães et ai., 2010) . 238 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management 1239 Fatigue management 13.5.3.1 Methods of Assessment 3D kinematic motion analysis is considered the "gold-standard" criterion method to evaluate jump performance; however, this procedure is time consuming and impractical in an applied setting. Another data collection method is to use a portable force platform. This can provide comprehensive data on a number of parameters, such as muscle force, power, rate of force development, jump height, and flight-time characteristics during jumping. Another useful variable that appears to be sensitive to fatigue changes after match play is the flight time to contraction time ratio or reactive strength index (RSI, jump height ! contact time). This represents the time from the initiation of the countermovement until the player leaves the force plate. Collecting data on several parameters is particularly useful given that peak force recovers more quickly than peak power and rate of force development in team sport players after a match (McLellan et ai., 2011). Some protocols may include single countermovement jumps, while other researchers have suggested multiple jumps (e.g., five repeated countermovement jumps) because several variables within this protocol might react differently than with a single jump, and this could be useful in understanding the mechanisms of fatigue (Cormack et al., 2008). Jump performance can also be assessed using a contact mat or similar system, but this provides only measures of flight time, predicted jump height based on vertical displacement, and contact time. This method does underestimate jump height when compared with a criterion measure, but it still has good reliability (Moir et al., 2008). The contact mat therefore provides a cost-effective alternative to measuring neuromuscular function when a portable force platform is not available. 13.5.3.2 Types ofJumpAssessment The countermovement jump (CMJ) is one method often used to assess neuromuscular fatigue. Although this test has been widely researched across a range of sports, inconsistency still exists with regard to how effective CMJ performance is as an indicator of fatigue. Most notably, studies by Cormack et ai. (2008; 2008a), examined the reliability of a number of CMJ parameters during inter- and intra-day repeat tests and the response of several of these variables following a single AFL game. These studies identified that CMJ height lacked the necessary sensitivity to optimally detect the changes associated with neuromuscular fatigue. They proposed that because CMJ height is a performance outcome, small alterations in technique are not acknowledged during data analysis, yet it is these minor modifications that occur when neuromuscular fatigue is present. It was proposed by Cormack et al. (2008) that the CMJ ratio of flight time to contraction time appears to be the most useful variable for monitoring neuromuscular stahts because of its high sensitivity and the substantial changes observed following match play. This is further supported by the work of Taylor et al. (in review). The authors looked at various kinetic and kinematic variables in order to examine their sensitivity to fatigue-induced neuromuscular status. They found jump height to be sensitive to changes in neuromuscular status, but this was not apparent in ali subjects. Findings showed that negative responses in the flight time to contraction time ratio were observed during deliberate overreaching for ali subjects. If the flight time to contraction time ratio is going to be measured, one simple method of assessing this is a drop jump (DJ). Astudy by Hamilton (2009) suggested the DJ may offer a more valuable insight into the neuromuscular changes associated with fatigue, due to the comparable muscle qualities required for success in a drop jump, agility tasks, and maximal running speed. 13.5.3.3 Dropjump protocol to assess recovery Each player should perform a thorough standardized warm up consisting of dynamic stretching and jumping activities. • As suggested by Taylor et ai. (2012) multi pie triais (>4) should be performed to ensure the most reliable results. 0 Instruct players to drop from a box height of 30cm then jump vertically for maximal height with minimal contact on the ground and with minimal flexion of lhe knee and hip. 0 Verbal encouragement should be given to players to perform maximally. o If using a contact mat, calculate the reactive strength index (RSI) by dividing jump height by contact time. 0 Take the mean of multiple DJ-RSI scores for analysis. 0 13.5.4 Psychometric and subjective monitoring tools Changes in subjective psychometric wellness and mood states have frequently been described as consistent, sensitive, and early markers of overreaching and overtraining in competitive athletes (Meeusen et al., 2006; Urhausen and Kindermann, 2002). Alterations in perceived fatigue and muscle soreness are also known to outlast reductions in neuromuscular performance and biochemical markers in elite team sport players (Twist et al., 2012). An advantage of subjective measures is their ability to capture other aspects of player >vellness, such as fear of failure, competi tive failure, excessive expectations from a coach or the public, and the demands of competition, as well as the professional and social areas of a player's life. This change in psychological state, or mental fatigue, is also known to alter an individual's sense of effort, forcing athletes to down-regulate their exercise capacity (Marcora et al., 2009). Measurement of these subjective markers is therefore deemed necessary to better understand fatigue and recovery in soccer players. A range of tools for the measurement of subjective wellness exist, such as the Profile of Mood States questionnaire (POMS), the Daily Analysis of Life Demands for Athletes questionnaire, the Recovery-Stress Questionnaire for athletes, and the Total Quality Recovery scale. These all enable coaches to easily monitor the con1plex psychophysiological stresses that are associated with fatigue and recovery, such as muscle soreness, sleep quality, mood disturbances, and altered attitudes to training. Unquestionably, the time course of changes in a player's psychological state during periods of intense training and underperformance is concurrent with physiological and performance changes. However, a concern raised by coaches is the subjectivity of these measures and the scope for athletes to manipulate responses to facilitate a favorable outcome. Moreover, when questionnaires are completed daily. coupled with the length of some questionnaires, concerns over player compliance need to be considered. 240 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management Fatigue management 13.5.4.1 Profile of Mood States (POMS) Sleep and Rcst (4 points) POMS is a psychological rating scale that measures the state of mind/rnood for sportspersons via six scales: Tension-Amciery, Depression-Dejection, Anger-Hostility, Vigor-Activity, Fatigue-Inertia, Confusion-Bewilderment. Players are asked to self-report a series of mood states. The original test was developed by McNair and co-workers and has 65 items. A shorter version of tl;ie POMS test was developed by Cella and colleagues in 1987 that contains only 11 of the original POMS items. The POMS scale has been used in thousands of scientific investigations and is very useful in assessing how players cape with training loads. Good night of quality sleep 3 points Daily nap (20-60min) 1 point Relaxation and Emotional Support (3 points) Fu!I mental/muscular relaxation ASAP after practice 2 points Maintaining a relaxed state throughout lhe day 1 point Stretching and Warm down (3 points) 13.5.4.2 RESTQ-sport (The Recovery-Stress Questionnaire for Athletes) Proper warm down after each training period 2 points There are also questionnaires available for monitoring recovery. The RESTQ-sport (Kellmann and Kallus, 2001) assesses the player's perception of recovery. The RESTQ-sport has been used worldwide to monitor perceived recovery. Coutts and Reaburn (2008) assessed whether the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) could be used to monitor changes in perceived stress and recovery during intensified training of rugby league players. They concluded that the RESTQ-Sport is a practical psychometric tool for monitoring responses to training in team sport athletes. However, the test cannot be executed daily because it asks the athlete about how often the respondent participated in various activities during the preceding three days and nights. Stretching all lhe exercised muscle groups 1 point 13.5.4.3 Total quality recovery (TQR) The TQR (Kentta and Hassmen, 2002) is a 20-point scale that assesses recovery as a combination of recovery actions and the athlete's perceptions of recovery. Players using the TQR concept collect points in a 24-hour period. A score of 20 is the maximum score, while 13 is considered the rninimum score. Scores below this arbitrary threshold could indicate under-recovery. This questionnaire makes the player aware of the important factors for boosting recovery, such as eating regularly and drinking enough before and after physical exertion. It is very easy to use and can be used daily, and it is easily assessed by both players and coaches. Table 13.4: Total quality recovery 13.5.4.4 Ratings of Perceived Exertion Ratings of perceived exertion (RPEs) are a qualitative and simple way of rneasuring the exertion perceived during training. It takes into consideration the mental and physical factors that cause the stresses of training. The concept of perceived exertion was introduced by Gunnar Borg as the "Borg RPE Scale®." This was done by placing verbal anchors from sirnple category (C) scales (rank order scales) at the best possible position on a ratio scale (a "CR-scale"), covering the total subjective dynamic range, so that a correspondence in rneaning was obtained between the numbers and the anchors. The range of 6-20 was created so the HR can be simply estimated by multiplying the Borg score by 10. This gives an approximate heart rate for a particular level of activity. Total Quality Rccovery 6 No recovery at all 7 extremely poor recovery 8 9 Scoring Recovery Points Nutrition & Hydration (8 points) 11 1 point Lunch 2 point Supper 2 points 15 Snacks between meals 1 point 16 Carbohydrate reloading after practice 2 points 17 13 reasonable recovery 14 good recovery very good recovery 18 Adequate hydration (8 points) During and post-workout poor recovery 12 Breakfast throughout lhe day very poor recovery 10 1 point 1 point 19 extremely good recovery 20 Maximal Recovery 1241 242 J FITNESS IN SOCCER 1 FITNESS IN SOCCER Fatigue management Fatigue management 13.5.4.5 Wellness questionnaires Possibly a more practically applicable solution is the use of shorter, simpler questionnaires, such as that proposed by McLean et al. (2010). A simple questionnaire such as this is time efficient, always available for daily collection, and able to capture data on a number of wellness measures. Figure 13.6 shows an example questionnaire adapted from Mclean et al. (2010). It includes fatigue and energy leveis, sleep quality, sleep duration, general muscle soreness, and stress and mood leveis. Another simple measure that can be added to a daily wellness questionnaire is "areas of muscle soreness, stiffness and pain." This can allow coaches, sports scientists, and medical staff to monitor any potential areas of discomfort and injury (Figure 13.7). Fig. 13. 7: A simp/e anatomica/ diagram that can be used to allow p/ayers to note down areas of soreness on their daily we/lness questionnaire (TopSportsLab) "Eo "Eo z z Y Analysis of Daily Wellness Questionnaire All five measures on this simple daily questionnaire are scored on a 1-5 scale, with 1 being very poor and 5 being very good. This allows for certain variables to be either analyzed on an individual basis or through a summed score (out of 25) that gives the Total Daily Player Wellness. Statistical analysis of the questionnaire, along with all other measures of fatigue and recovery, will be explained in the next section. ro o~ - ~ o o "' o ""o ~::; ID ~ .!!! o X 0 ID <!) "' ·'ª" "iii àe. OJ OJ ü; Fig. 13.6:. Example Dai/y Wellness Questionnaire. (Adapted from Mc/ean et ai., 2010) 13.5.5 Statistical analysis The fundamental goal for any player-monitoring system is the ability to inform decisions and ultimately improve performance. Although daily assumptions can be made using various data-collection methods, as discussed above, it is important to note that it can take months and even years of data collection to truly understand what the data means and how to use it. Jumping to conclusions based on an inadequate amount of data can lead to poor decisions being made that have a negative effect on performance. To successfully collect, analyze, and interpret data, the first step is your collection protocol. Below is an example of a typical daily routine that can be carried out each morning in around 20 minutes. 8:30am - Players arrive at the training ground and fill out Daily Wellness Questionnaires as they collect their training kits. 8:35am - Players report to the gymnasium for a one-minute HR assessment. This involves a few minutes of relaxation followed by the one-minute HR reading to assess HRV and Resting HR. 8:40am - Following their HRV assessment, players perform a standardized warm up before completing four drop jumps on a contact mat to assess daily RSL 243 244 1 FITNESS IN SOCCER FITNESS IN SOCCER 1 Fatigue management Fatigue management Once this protocol has been cornpleted, players are free to have breakfast and relax until the start of training. ln this time, the data can be analyzed by support staff and reported to coaches, detailing players who require rest or a reduced training load and players who are in an optimum condition to train fully. If this system is to work, an efficient data-collection database and analysis system needs to be in place. Following data collection, the next important step is analyzing the data and deciding which changes in the daily measures warrant intervention. The use of arbitrary thresholds (e.g., a change of 5%) has been discouraged (Twist and Highton, 2013) because the variation observed, when identifying a fatigued condition, may fall within the boundaries of typical variation for some measurements (e.g., jump measurements -1-6%; Cormack et al., 2008). One possible statístical method that may provide a better insight into the magnitude of change is the smallest worthwhile change statistic (SWC) (Hopkins et al., 2009). This is calculated by multiplying the between-player standard deviation by 0.2. Figure 13.8 depicts an example of how this method can be used to show a positive or negative change in monitoring data. Dally assessment of HRV P/aycr 1 Player 2 Player3 Player4 Playcr 5 Avcrage 50 swc Mon 85.9 79.9 87.9 63.0 79.0 Toe BS.2 79.9 87.4 62.7 79.9 Wed 88,7 81.4 86.2 64.G 79.9 Thurs 85.7 81.9 82.7 65.4 81.4 "' 85.7 ll4.7 87.6 65.B 81.9 Chang e Thur-Fri o.o 2.8 4.9 0.4 0.5 No Change Positive Change Positive Change Trivial Trivial 79.8 8.4 1.68 Fig. 13. 8: Example of monitoring changes in rolling average HRV using SWC. This method can be applied to ali monitoring data to give coaches and support staff a qualitative description of the magnitude of daily changes in recovery status. 13.6 TAPERING Tapering is part of fatigue-management strategies. ln the last phase of the microcycle, mini-tapering strategies should be applied. Tapering is one of the most important challenges for a coach, because it is a method of strategically unloading athletes in order to reach peak leveis of preparedness for competitíon. Various factors have to be taken into account in this regard, such as the accumulated fatigue of the preceding days, physical and psychological stress, and recovery (e.g., sleep, nutrition, etc.). Tapering is a progressive non-linear reductíon of the training load during a variable period of time in an attempt to reduce the physiological and psychological stress of daily training and optimize sports performance (Mujika and Padilla, 2003). Various forms of tapering have been described in the literature, such as a linear taper in training load (Hickson et al., 1982), an incremental stepwise reduction (Houmard and Johns, 1994), and an exponential taper with slow or fast time-constant decay of the training load (Banister et al., 1995). Training parameters like intensity, duration, frequency and volume can be altered to lower the training Ioad in the days or weeks preceding a competition or match. This is done in order to reduce accumulated fatigue and unmask fitness leveis, because residual fatigue may mask or attenuate fitness gains that have occurred through overload training (Kuipers and Keizer, 1988). This decrease in training load could, however, compromise training-induced adaptations. Lower leveis of training load and the subsequently decreased leveis of accumulated fatigue can cause a partial loss of training-induced performance adaptations, a process known as detraining or deconditiong. Coaches must determine the extent to which the training load can be reduced at the expense of the training parameters while retaining or improving adaptations (Mujika, 2011). Exercise intensity during a taper seems to be the key in maintaining or elevating performance. Research has demonstrated that low training intensities either maintained or deteriorated performance (McConnell et al., 1993), while tapers using intensities of 90% V0 2max (Costíll et al., 1985) resulted in enhanced performance. Houmard and Johns (1994) advised using interval training work (>90% V0 2maJ with sufficient recovery behveen bouts to maximize exercise intensity. They suggest this is necessary to maintain training-associated adaptations despite the reduction in training volume. This was confirmed by Bosquet et al. (2007) who found that maximal gains are obtained with a tapering interventíon of a two-1veek duration where the training volume is exponentially decreased by 41-60%, without any modification to either training intensity or frequency. 13.6.1 Effects ofTaper Tapering provides for: • increased hemoglobin • increased hematocrit value • decreased percentage of neutrophils • increased red blood cell volume • increased production of new red blood cells • increased buffer capacity for lactíc acid • increased muscle glycogen • increase in testosterone • reduction of cortisol • increase in the testosterone-cortisol ratio o increased sleep (This is important because of gro1vth hormone being released during certain phases of sleep, resulting in muscle tissue repair [Taylor et al., 1997]). • improved perceived sleep quality 245 246 1 FITNESS IN SOCCER FITNESS IN SOCCER Fatigue management 13.6.2 Rules for good tapering 13.6.2.1 lntensíty Intensity during tapering must be rnaintained in arder to avoid detraining. It is through the reduction of the other training parameters (i.e., volume, frequency and duration) that efficient tapering should be achieved. Bosquet et al. (2007) highlighted that the training load should not be reduced at the expense of training intensity during a taper (Bosquet et ai., 2007). 13.6.2.2 Frequency Decreasing training frequency has not been demonstrated to improve performance. Bosquet et al. (2007), however, highlighted that frequency of training is closely linked to other training parameters, such as volume and intensity. 13.6.2.3 Volume Research suggests that the volume of training can be reduced to 50-70% of normal without the special adaptations specific to the training being compromised. Mujika et al. (2000) reported some years ago that better performance ensues from low-volume rather than moderate-volume tapers. This finding was confirmed by Le Meur et al. (2012) when they suggested that athletes would maximize taper-associated benefits by roughly halving their training volume. 13.6.2.4 Duration Research shows that the optimal taper duration depends on the pre-taper training volume and intensity, and it is generally 4-21 days. Tapering takes longer for speed and strength athletes than it does for endurance athletes on account of the nervous system recovering more slowly. It may be concluded that a taper duration of 7 to 15 days appears to represent the threshold between the positive effects of lowering accumulated fatigue and the negative effects of deconditioning (Fitz-Clarke et al., 1991) on performance. 13.6.3 Conclusion The effects of mini-tapers have not yet been examined in team sports. Almost all research on tapering strategies has focused on individual (endurance) sports. Based on this research, we suggest the following strategies within the microcycles, mesocycles, and macrocycle of team sports, 13.6.3.1 Microcycle Mini-tapering strategies are applied during the last two days before a match to reduce levels of accumulated fatigue, unmask fitness levels, and increase freshness and preparedness. 1. Reduce the training duration by 50-60%. 2. Training intensity remains the sarne. 3. Increase the recovery time between exercises. 4. Stimulate mental recovery. 5. Stimulate sleep extension. 6. Wear compression socks while traveling. 7. Skip commercial activities and sponsor needs. 8. Manage media demands. Fatigue management 13.6.3.2 Mesocycle 1. Tapering strategies are applied every third week to allow the body to recover while avoiding detraining: 2. Reduce the total training volume by 60% by reducing the duration of training sessions, 3. ICeep the volume of high-intensity training sessions high. 4. Increase the recovery time between exercises. 5. Reduce training frequency by 20%. 6. Activities during tapering should be specific to the technical/tactical requirements of the sport. So, in particular, reduce activities that are not specific to the sport. 13.6.4 Macrocycle There is an ongoing discussion in the media about players' recovery time before the start of every major tournament. Many players sustain injuries during such toumaments, and some "star" players remain below their normal leveis. National federations try to solve this problem by shortening the competition or bringing it forward. Everyone probably remembers the 1992 European Championships when Denmark unexpectedly won the tournament. Ten days before the start of the UEFA European Football ChampionshipT"' finais qualifiers, Yugoslavia were excluded and replaced by Denmark, the runners-up in their qualifying group. National coach Richard Meller Nielsen had to contact his players, many of whom had already left on vacation. They Jiterally changed from their holiday clothes into training gear. Some players had already been on vacation for four weeks. According to many observers, the psychological and physical freshness of the players had a decisive factor in the success. Two scientific studies describe preparations for an international toumament. ln the first study, Bangsbo et al. (2006) describe the preparation of the Danish national team for the 1996 European Championships. The players were given a 1-2 week break before the start of preparations, followed by 18 days of training divided into two nine-day phases. The intensity of the exercises was identical in both phases, but the volume was reduced in the second phase. The researchers emphasized that it is important to measure the training load during all exercises. The load during non-fitness exercises also has to be taken into account. ln 1998, France won the World Championships. Four years later, the sarne national team was eliminated at the group stage, despite fielding a virtually identical team. A study conducted in 2003 (Ferret and Cotte, 2003) describes the difference between the two preparation programs. In 1998, 14 players arrived 32 days before the start of the competition, 11 players arrived 25 days before, and finally, three players started their preparations 19 days before the start of the competition. Four years later, 7 players started preparing 25 days before the competition, 15 players started 18 days before, and one player started only 8 days before. According to the authors, the team had enough time in 1998 to prepare properly for the World Championships by optimizing the players' fitness. The staff organized two training camps (Tignes and Clairefontaine). The group started with high volumes of training, followed by three weeks of tapering, during which a few friendly games were played and the players were given rest periods to eliminate fatigue. ln 2002, 1 247 FITNESS IN SOCCER Fatigue management FITNESS IN SOCCER 2481 Fatigue management the players had only a few days to prepare. During this period, it was impossible to rebuild fitness and still allow tapering. Medical and biochemical markers showed that the players were fatigued. ln these circumstances, it was impossible for the staff to prepare the team properly. SUMMARY ln elite soccer, off-season and preseason periods are becoming shorter and shorter, and players are increasingly expected to play in more cornpetitive games throughout the calendar year. Therefore, performance stabilization for the modem soccer player is extremely important, and correct fatigue management strategies are becoming paramount in the modem game. Simple, inexpensive wellness questionnaires can be used by coaches to help monitor the fatigue status of each player, providing easy-to-understand information in order to adjust the training program accordingly. The implementation of tapering and recovery strategies throughout a competitive season is critical to stabilize the performance of the players, so that they can perform as close to their peak as possible over an extended period of time. It is important that the coach pays particular attention to the needs of the individual player, ensuring that each player's training program is periodized correctly to avoid accumulation of fatigue and staleness. Periodization is discussed in more detail in the following chapters. ilorref-"n,J. and Lambert, M.I., 200S. Autonomic control olhc.1rt rale during and aftcr excrdoc. Spor!S mcdicin~, 38(8), pp.633·M6 llosqucl, L, Montpclit,)., Arvu;ais, D. and Mujil:a, !., 2007. Effo:lfi of tapcring on performance: a mcta·analysw. 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Sporls Med., 42(7), pp.~b- SM. Wciss S K 2006 HcltcrSlcep for)'o(lr Dabr &Cl1ild. Toronto; Robert Rose lnc. M <l WC>Js~I, j, ;nd \\~m, A. 1994. Effcci 0 1 otn:lching on thc in!cn~ity of dclaycd·onsct mundc son:ner.,:;. Clinicai Joum~I oi Sprt ' e icmc, {\fif~~~-~l., Cronin, /,ll. mtd Hing.. A.H., 2006. Phy~lo!ogknl =·ponsc to watcr immersion.Jouma! ofSporW M~idn~, 3b(~), P~7~;: 765. Young. w., Hawkcn, M. nnd McDona!d, L., 19%. Rclationsh'1pbdwccnSpccd anel Ag1l1ty andStn:ni;lhQu~htEco m,\(l•tra rnn u º' football. Stn:ngth & Condltioning Conch, 4(·1), pp.3-6. . . . .. Zat~iornl:r, V.M., 1995. Sdcnce and practlce oi strcngth lr~mmg. Champa1;;n, ll: H(lman Kmchc:;. FACULDADE' OE DESPORTO DA UNIVERSIDADE DO PORTO 252 1 FITNESS IN SOCCER 1 FITNESS IN SOCCER Periodization in soccer Fatigue management 1 PERIODIZATION IN SOCCER Jan Van Winckel, Kenny McMillan, Cario Buzzichelli, David Tenney, Paul Brad/ey Periodization is a planned/programmed distribution or variation in training methods and means on a cyclic or periodic basis. As highlighted in the previous chapter, an important aim of periodization in elite soccer is fatigue management. Periodization for soccer entails organizing the season in a structured manner to ensure the level of performance is kept as consistently high as possible (performance stabilization) throughout the season. To achieve this, periods of loading, unloading (recovery), and tapering (for the most irnportant competition(s) of the year) have to be sensibly arranged. Periodization refers to the planned alternation of loading and unloading (fatigue management), the structured sequence of which physical ability (i.e., strength, speed, endurance) to develop, and the division of the annual plan into distinct periods. 14.1 HISTORY OF PERIODIZATION The Ancient Greeks used very elementary plans to prepare for the Olympic Games. The legendary Milo of Croton (6th Century BC), winner of six Olympic Games, was one of the first to use a primitive form of periodization by varying his training load during his training program. Milo began his training most days by lifting a calf, and as the animal grew bigger, the lifting load increased, consequently improving his performance. At the end of his training process, he was able to carry the animal around the Olympic stadium. Galen (129-200 AD) was a Roman physician, surgeon and philosopher (Nutton, 1973). At the age of 28, he returned to Pergamon in Italy as a physician to the gladiators and became one of the first to write about periodization. He believed that various types of exercise needed to be blended in arder to improve performance. He divided exercises into three categories: without "hostile" movement, such as weightlifting; quick exercises, such as ball games; and exercises with a "hostile" nature, which we now refer to as plyometric exercises. It was not until the iun-up to the Olympic Games in Helsinki (1952) that the experience of the Russian coaches became the impetus for the methodological principies of training systems. Researchers emphasized that the competition schedule had to be integra- 253 25 4 1 FITNESS IN SOCCER Periodization in soccer ted into the overall system and that "active rest" was very important. The former Eastern Bloc, especially the Soviet Union, believed in a multi-year development preparation period, and the coaches there delayed the special~zation phase of t~e sport for longer. This was in contrast to Western coach~s who 1mplemented spec1alization much earlier and without any thorough multilateral development. ln the Soviet Union, as well as in other Eastern Bloc countries, a clear sports program existed to train children from elementary school level up to the elite level. ln this way, they monitored and controlled all the factors. Dr. Verkhoshansky hims~lf went so far as to say that periodization was based on the principles of commun1sm. ln the West, it was impossible to adopt the sarne training approach, because th~ culture did not permit such a thing. East Germany could obviously not b~ left b~h1n~, a~d in 1956, the German High School for Physical Culture was estabhshed in Le1pz1g. With the Cold War as the catalyst, sport became the flagship of various countries. State support was more the iule than the exception. However, the medal also had a darker side. "Sport for all" was an empty concept, because East Germany .se~ec­ ted children at a young age and only invested in the very strongest. Two d1stinct trends then emerged from 1970 onwards: The West invested time_ ~nd_energy i~ t~e different areas of sport-such as school sports, health and rehab1htahon-while 1n the East, the emphasis continued to be focused on the elite. It was in this race. for better performances that periodization models surfaced. ln th~ 1970s, many sc1entists, mainly Bastem European, published a large number of im~o:tant works. on periodization and the training process, such as Arosiev and Kahrun (1971), D1atschkov (1974), Zatsiorsky (1972), Matvejev (1974, 1981), Kusnezov (1972), Harre (1974), Vorobiev (1974) and Tschiene (1977). Matvejev, the father of periodization (1964), has not always received the recognition he deserves. V1ce-Pres1dent of Sport Kolessov stated in 1991 (Sovietsky sport, 1991) that the "outdated" system of Professor Matvejev should not be pursued anymore. The origins of soccer science lie in the former Soviet Union. The Russians were the first to practice soccer science in a structured •vay, with Valeriy Lobanovskyi playing an important role in developing the kno\vledge and know-ho•v and intertwining soccer and sport science. Lobanovskyi used statistics and data as a means of gaining competitive advantage in sport more than two decades before the foundation of specialized companies such as TopSportsLab0 , Amisco, and ProZone. Lobanovskyi started as the coach of Dneproprtovsk (19691973), recruiting Anatoly Zelentsov, a statistician who was at the time the Dean of the Dneproprtovsk lnstitute of Physical Science. Soccer became for them a system of 22 ele- FITNESS IN SOCCER Periodizaffon in soccer ments (hvo ~ub-systems of 11 elements) moving within a defined area (the pitch) and depend1ng on a series of restrictions (the Jaws of the game). They had the players perform tests and then analyzed the results via a computer. Lobanovskyi even \Vent so far as to let Zelentsov and his computer system make the selection for the European Championships in 1988. The coach, who died in 2002, surprised friend and foe alike by playing scientific "total football" with Dynamo Kyiv (1984-1990) long before Rinus Michels embodied "total" football in the Netherlands. He created a system that evaluated every action in a match. A group of scientists noted each successful and unsuccessful action relating to passes, tackles, shots and dribbles. These data were then analyzed by a computer, enabling each player to be evaluated for "intensity, activity, error rate and effectiveness." 14.2 TYPES OF PERIODIZATION Periodization improves performance through various mechanisms: 1. A planned, progressive overload favoring positive morpho-functional adaptations through planned alternation of loading and unloading 2. Avoiding reaching criticai leveis of fatigue and overtraining (Morton, 1997) 3. Tapering at the right moment to reach peak condition 14.3 SEASON PLANNING There are different ways of preparing players for a game or season. There is the "ad hoc" approach (deciding from day to day), the intuitive approach (based on the '.'best practice" of the coach), and structured periodization. There are definite gaps 1n the_current knowledge because periodization theory is based largely on empirica! ev1den~e, relate<l research (e.g., overtraining), anda few mesocycle-length variatlon stud1es. Most of these involved experimental periods no longer than two to three months and/or subjects with limited training experience, whereas no actual multiple mesocycle or integrated shtdies (e.g., combined strength/power and sp~ed/endurance training) on advanced athletes have been published in English {Phsk and Stone, 2003). Moreover, most of the scientific research published is in the domain of. strength training, and it is not easy to translate these findings to ~eam sport sett~n?-s. For example, training parameters such as volume and intensity in strength tra1n1ng are completely different compared to training parameters in soccer. We have compiled a classification system belO\V that should enable soccer coaches to better understand the mechanisn1s of periodization. This format, which has not been used anywhere else, attempts to a reach a consensus with regard to the terms used in the research literature. We have deliberately used ali the terms used in publications in order to make it easier to find more information via search engines and/ or publications. 1 l55 256 FITNESS IN SOCCER 1 FITNESS IN SOCCER Periodization in soccer 1257 Periodization in soccer 14.3.1 Season-planning components Periodization can be considered a process of structuring training into phases to maximize athletes' chances of achieving peak performance and therefore their competitive goals (Bompa, 1999). Accordingly, periodized training programs are typically structured into macrocycles, mesocycles, and microcycles that progress from extensive to intensive workloads, as well as from general to special tasks (Plisk and Stone, 2003). Before discussing the types of periodization, we first give an overview of the yearly planning components below. There is a chance you will find other definitions in the literature, but those used here are the most widely supported and accepted. 1. Multi-year plan or megacycle. For athletes, this is often a four-year (or Olympic) cycle. ln soccer, this cycle is used for younger players in academies, where long-term objectives can be set using models such as the Long-Term Athlete Development (LTAD) model designed by Dr. Balyi (Ford et ai., 2011). 2. Annual plan (Bompa)/Annual Macrocycle (Soviets). According to most models, the annual plan comprises three macrocycles: the preparation phase, the competition phase, and the transition phase. The preparation phase is normally divided up again into general and specific preparation, and the competition phase is split into a pre-phase anda competition phase. 3. Phase (Bompa)/Macrocycle (Soviets). The term "macro" comes from the Greek word "makros," meaning "big." The term "cycle" refers to something that is constantly repeated. It defines the general direction of the training process in a certain period (general or specific preparatory, pre-competitive or competitive, transitory). 4. Macrocycle (Bompa)/Mesocycle (Soviets). A macrocycle (Bompa) or mesocycle (soviets) is a period of 2-5 weeks that specifies the direction of the training process for each of its components (i.e., physical strength, speed, endurance, and technical/tactical). ln this timeframe, one to three loading microcycles are followed by one or two unloading microcycles (thus reducing intensity and/or volume, but usually just volume). lt is particularly during these periods of reduced load that progress can fully manifest itself. 5. Microcycle (from match to match or week to week). The term "micro" comes from the Greek word "mikros," meaning small. This microcycle rons from match to match in most cases, although it can be longer in the preparation phase and shorter in the competition period. 6. Daily planning: • Warm up o Central section • Rehabilitation and progression training • Cooling down ln this book, we use the terms macrocycle (for preseason, in-season, off-season, etc.), mesocycle (2-5 weeks in length) and microcycle (from match to match). 14.4 TYPES OF PERIODIZATION ln this section, we will see how different periodization models can be distinguished. We do this on the basis of four types of classifications: 1. Volume and lntensity Periodization models that vary intensity and volume. 2. Physical abilities Models that vary the basic characteristics (physical abilities) of the sport being h·ained (e.g., aerobic fitness, speed, etc.). 3. Workload Models that vary in workload. 4. Integrated Multidisciplinary models. Fig. 14. 1: OveNiew of the different phases of a periodization model. zss I FITNESS IN SOCCER FITNESS IN SOCCER Periodization in soccer Periodization in soccer 14.5 PERIODIZATION MODELS: INTENSITY ANO VOLUME The basic concept of a trade-off between intensity and volume seems pretty elementary, but it has important ramifications because the interaction of these variables drives many of the decisions made when designing training programs (Plisk and Stone, 2003). Most scientific research only distinguishes between the variation in volume and intensity. Volume can be defined as the total duration of the training, as well as the number of sets and repetitions in strength training or the number of kilometers in a cycling race. Correspondingly, the intensity could be the running or cyding speed, for example, or the one-repetition maximum (lRM) percentage in strength training. 14.5.1 Linear models This brings us to the final problem: The model implies that peaking will occur at the end of the season. Team sports like soccer do not require a peak in performance. This could possibly be handled by using a multi-peak approach (Bompa, 1984; Wilks, 1995; Fleck and Kraemer, 1997). For example, an athlete can peak in the 60m indoor event in the winter and in the lOOm sprint in the summer season. Research has shown that bi- and tri-cycle models have a greater impact than a model with a single peak. From this, Poliquin (1997) concluded that it was the variation of the multi-peak models that was responsible for the greater progress. Bompa (1983) and Tschiene (1977) recommended periodization of this kind mainly for sportsmen tvho have two or more periods of competition per year, followed by so-called transitory phases (Bompa) or prophylactic intervals (Tschiene). These are short periods of relative rest, during which the body can recover well, injuries can heal, and motivation can also be regained. 14.5.1.1 Linear periodization and single, double and tripie models Leonid Metveyev, a Russian sports scientist, presented a model in which the annual macrocycle begins with a high volume of low-intensity training. The Metveyev model and the Western spin-offs have the characteristic of intensity and volume working in inverse proportion. High ,. --- ....... . ./..-:?'··············· . . . .. . ( Volume lntensity Performance .•.•....··············:·:·:, ... ............... low Time Fig. 14.2: Example of linear periodization in which the volume decreases and the intensity increases This model is particularly suitable for novice athletes. The body easily absorbs the load because of the high volume and low intensity in the initial phase. The main criticisms of this model are: • General preparation is too voluminous and general, thus making the athlete detrain his specific physical abilities. • Preparation phase is too long for today's professional team sports, which have short preparation phases and long competitive phases. .. • Progression is too linear. This, in fact, is not a substantiated criticism because from the chart, it is impossible to depictwhat happens at the level of the microcycles and mesocycles, which can, and should, have alternations of loads. • Unlike individual Olympic sports, team sports usually do not require an ultimate peak at the end of the season. 14.5.1.2 Reverse linear Reverse linear periodization follows the modification in intensity and volume but in a reverse order to linear periodization models, increasing volume and reducing intensity (Rhea et ai., 2003). Reverse linear periodization methods are sometimes used in sports where aerobic endurance is important (e.g., cycle racing and triathlons). 14.5.2 Non~linear, undulating and daily undulating models In a non-linear periodization training model, intensity and volume are changed much more frequently compared to linear models (Kraemer and Fleck, 2007; Fleck, 2011). 14.5.2.1 Undulating The undulating method makes use of alternating phases of intensity and volume within the microcycle, mesocycle or macrocycle. At the microcycle level, this can be achieved by alternating intensities (and energy systems) day by day (e.g., lightheavy-light-medium or heavy-medium-light). At the mesocycle level, it can be achieved by either alternatíng the average load of each microcycle (e.g., heavylight-medium-light) or by including an unloading microcycle at the end of the mesocycle. At the macrocycle leve}, it can be achieved by alternating different qualities of the sarne physical ability (e.g., strength-power-strength-power). Several studies have concluded that these undulating periodization models produce significantly better results than non-periodized or strictly linear models (Fry et al., 1992; Stone et al., 1999; Zatsiorsky, 1995). 14.5.2.2 Dai/y undulating model (DUP) The daily undulating periodization (DUP) consists of increasing and decreasing intensity and volume on a daily basis, and it is often planned according to the athlete's feedback. The variation of training components is more frequent and lasts for shorter periods (Fleck, 1999). 1259 260 1 FITNESS IN SOCCER FITNESS IN SOCCER 1 Periodization in soccer PeriodizaHon in soccer 14.6 PERIODIZATION MODELS: PHYSICALABILITIES The following models differ from each other in the way in which different physical abilities (e.g., aerobic, endurance, speed) are trained. ln general, three different methods can be distinguished: 1. Unidirectional ar sequential method. 2. Parallel, concurrent or intermediary method. 3. Combined model. 14.6.1 Unidirectional, block or sequential method The sequential method is characterized by a phased unidirectional approach for each physical component. This method is especially applied to the mesocycle, with each physical ability, such as speed, being trained separately within a certain period. Endufáílce The sequential development of a physical ability can be integrated with the sequential developments of other abilities. For example, all of the abilities labelled "a" above could be trained simultaneously (Bompa, 1983) in a "complex" or "concurrent" plan, or they could be separated into "blocks." A concentrated block usually separates strength development from speed or endurance. Concentrated block training results in a long-term delayed training effect (LDTE) of 4-12 weeks, usually peaking after a duration equal to the block's duration. The advantage of this system is that no other aspects are trained, thus avoiding additional strain on the body and making it easier to train one particular component in overload. This is often found among advanced athletes because of a great <leal of the training load being applied to one single aspect. The model proceeds from the principie that residual training effects remain, and these can be built on in the next mesocycle. ln this way, more stable progress can be made with long-term effects. Since block training is often associated with injuries resulting from sudden transitions between two phases, less sharply delineated periodizations are often recommended. 14.6.2 Parallel, concurrent or intermediary method Fig. 14.3: Exampfe of sequential periodization The concurrent model is used to train different physical abilities (e.g., endurance, strength and speed) during the sarne phase in order to promote multilateral development. This fits into the macrocycle, the mesocycle or even the microcycle. The concurrent model makes it possible to place emphasis on a particular factor, such as by increasing the load for a particular component. This type of periodization may create a synergistic effect, allo\ving one skill to strengthen another during buildup. Examples of the sequential method for the various physical abilities: Strength, 1. Preparation: a. Anatomical Adaptation b. Hypertrophy c. Maximum strength d. Specific Strength 2. Season: Retaining and maintenance of load Endurance: 1. Preparation a. Aerobic endurance b. Mix of aerobic and specific endurance c. Specific endurance 2. Season: Specific endurance Speed' 1. Preparation a. Aerobic endurance b. Anaerobic endurance c. Alactic speed (without accumulation of lactate) d. Specific speed 2. Season: Specific speed Eridur:ance Strength Power Pre;rnrntiort General Prcp~rJtion Spedfíc Preparntion f!.11bu1!óirtg ol phy~lta! ilbilitku Fig. 14.4: Example of concurrent periodization ln a preparation phase. Eac/J physical ability is trained together. When using this model, it is important to assess the interaction of the different abilities. The interaction between different physical abilities is referred to as the "interference phenomenon" (Docherty and Sporer, 2000). This phenomenon occurs \Vhen adjustments resulting from training compete with other specific adaptations. Strength training, for example, has a profound negative influence on muscle mitochondria, which are essential for endurance (MacDougall et al., 1979). Ho-ivever, if the interference phenomenon is accounted foi~ these physical abilities can be trained perfectly well in the sarne cycle, especially since soccer players normally don't need to fully maximize a single aspect. A soccer player must therefore try to 261 262 FITNESS IN SOCCER Periodization in soccer 1 FITNESS IN SOCCER Periodizatíon in soccer maintain a certain levei in all physical abilities and improve on the specific requirements of their positions (e.g., acceleration for a winger). A great <leal of research has been conducted over the last decades into the influence of strength training on aerobic training and vice versa. It is obvious that the hvo types of training will interfere with each other because of the body wanting to constantly adapt to the load (Dudley an<l Djamil, 1985; Chromiac and Mulvaney, 1990). Several studies have shown that concurrent training can induce suboptimal strength and/or endurance adaptations (Gergley, 2009; Glowacki et al., 2004). If both types of load are being trained, the body's adaptive capability is <lisrupted. The challenge in practice is to integrate strength an<l en<lurance training so they both enhance, rather than interfere with, each another. There is little information regar<ling soccer-specific concurrent training an<l the effects of training or<ler. Recent research in soccer (McGawley an<l An<lersson, 2013) foun<l a positive effect of the concurrent training approach on key measures of soccer performance, but the or<ler of completing high-intensity, run-base<l training an<l strength- and power-base<l training appears inconsequential to performance a<laptations. lities are maintaine<l. The player will then make progress on one aspect, with the others remaining at the sarne levei. This training model therefore not only combines all the physical abilities within a particular stage; it also ensures progress in a particular quality at the sarne time. 14.7 WORKLOAD A third classification of periodization is made based on the distribution of workload. 14.7.1 Stepwise loading This type of periodization increases the training load in each microcycle and <lecreases the load in the final microcycle. In this final phase, the body converts the workloa<l into progression (supercompensation). Stepwise model 14.6.3 Periodization models: Combined model The aim of the combined model is to combine the benefits of the two previous models, namely the unidirectional approach of the sequential method and the advantages of block training. This system trains the <lifferent physical abilities in the mesocycle and a primary or secondary objective in the microcycle. The player thus adapts physiologically (functional over-reaching) to a specific ability, while the other parameters will be maintained (retaining loa<l). This can prevent stagnation, over-training and fatigue. Zatsiorsky emphasizes that this model has the advantages of the cumulative results of training while accentuating the specific training effects of the "loading" of a specific quality. This ensures greater improvement in performance. The positive accumulation of these training effects results in a more uni<lirectional increase in work capacity. D D D D BD D Rebuilding of physical abilities Week 1 Week2 week3 Week4 WeekS Fig. 14.6: Example of a stepwise modal 14.7.2 Reverse step loading ln this method, the training load is re<luced in each microcycle. 14.7.3 Fia! step loading ln this model, a high training load is set for all aspects during a specific period. The training loa<l is then reduce<l to allow supercompensation to take effect. The flat step loading model should not be used for mesocycles longer than three weeks (i.e., two loading microcycles and one unloa<ling microcycle, or 2+ 1 or 2:1). Flat step loading Maintenance Fig. 14.5: ln this model, a specitic ability is trained each week, while lhe other systems are maintained. In simple terms, the combined model is a model in which one specific quality (e.g., spee<l, en<lurance, etc.) is traine<l as the primary objective, while all the other qua- Week6 Week 1 Week2 Fig. 14.7: Example offlat step loading Week3 Week4 1 263 264 1 FITNESS IN SOCCER Periodization in soccer FITNESS IN SOCCER Periodization in soccer 14.9 TYPES OF MICROCYCLES 14.7.4 Pyramid loading The training load is increased to a maximum and subsequently reduced again. In the literature, many terms are used to label the different microcycles. Below we set out the terms used in the literature and the way they are distinguished. Pyramid loading Terms used in literature Weekl Week2 Week3 Week4 WeekS Adjustment, rebuilding, initializing Low to medium load, gradual increase in work!oad and intensity Restoration, regeneration Low load (low intensity, duration, frequency); physical and mental recovery Loading, building, devetopmental Progressively higher volume and/or intensity lmpact, shock Extreme workloads {S!eamaker, 1989). These microcycles could cause many injuries because of an unaccustomed levei of intensity and/or volume. Scholastic heritage of the Eastern Europe training theory with little practical application. Tapering, pre-competitive, tuning, peaking, unloading Low toad, high intensity Maintenance, competitive Medium load with emphasis on event-specific performances Fig. 14.8: Example of pyramid /oading. 14.8 INTEGRATED There are also periodization models that pay attention to all the components of sport training símultaneously. 14.8.1 Technical Matvejev was the first scientist to incorporate the technical component into the periodization model. The skill-strength periodization model (SSP) was rnainly used in the Soviet Union. The model proceeds from the principie that the technical component has to be trained first and followed by the strength component. 14.8.2 Psychological Balague (2000) is one of the fe•v scientists to devote attention to the integration of the psychological/mental aspect. She developed a model in which psychological preparation goes hand in hand with physical development during different training cycles. 14.8.3 Tactical periodization One of the best examples of synchronization between tactical and physical periodization is the \VOrk of José Mourinho. He coordinates the two disciplines during the year and programs his exercises in such a way that the players train the tactical principles while also pursuing physical periodization at the sarne time. We \Vill elaborate further on this in Chapter 15. Load leveis 14.11 PERIODIZATION IN SOCCER Applying periodized planning to team sports poses unique challenges due to the variety of training goals, volume of concurrent training and practices, and extended competition season (Gamble, 2006). Planning must attempt to prepare players to peak for a match every week for the entire season. In elite soccer, peaking for every match is not possible. Matvejev wrote back in 1977 that periodization is not justa simple plan but rather a set of la\vs or basic principies that accompany the training process. Bompa (1983) stated that periodization is the process of dividing the season into smaller parts, \vith the objective of achieving the best performances during the most important phases of the season. According to Plisk (2004), periodization is a programmed variation of training content and training methods on a cyclical basis. Kraemer (2004) added that, in addition to variation, periodization must also consist of programmed recovery periods to boost recovery and bring the athlete (player) back to his present potential. Periodization is a term that is often used indiscriminately. It is difficult, if not impossible, to examine periodization models in high-level soccer and map out their effects. The model described below is therefore based on scientific research and brings together different aspects that can be found in the scientific literature. This is clone on the basis of several strategies. When we use the term "periodization" in this book, we refer to the different fatigue-management strategies that can be applied when planning the season. Periodization in soccer is therefore the strategic planning of fatigue management. 1265 266 FITNESS IN SOCCER 1 FITNESS IN SOCCER Periodization in soccer 1267 Periodization in soccer 14.11.1 lntegrated periodization Physical periodization must be synchronized with all the other aspects of soccer. We refer to this as an integrated approach. Good planning takes account of the following periodization components: • Technical periodization • Tactical periodization • Physical periodization • Psychological periodization o Communication and team building The main focus of training will be different in any sport. ln soccer, however, one component cannot be separated from another. Periodization can therefore best be defined as a logical, phased method of organizing training variables for the purpose of raising the technical, tactical, physiological and psychological potential of a player in arder to reach specific objectives. 14.11.2 Different phases of drawing upa season plan Before we start with discussing periodization strategies specific to soccer, let us first give an outline of the method that will be applied: 1. Formulate objectives and ambitions. 2. Divide the season into manageable phases. o Setting up the first draft of the season plan o Assessing the current situation • Adjust goals and ambitions. 3. Conduct a strength-weakness analysis of the group and the individual. 4. Adjust the training objectives in the mesocycle for the group and the individual. 5. Differentiate and individualize periodization. ../ Formulate objectives and ambitions Objectives and ambitions are set before preparation begins. These goals are agreed upon by everyone in the club (i.e., players, staff and management). There is a difference between an objective and an ambition. An objective could be, for example, to secure fourth place, qualify for the Europa League, or promote two youngsters into the first team, An ambition could then be, for example, to play attractive soccer or compete for the title. It is important for objectives and ambitions to be shared by everyone and recorded in a document that is communicated externally. This ensures that no false expectations are created. Season 2014~2015 Objective Reaching the final stage of the European League Tapering before champions league games Fourth place in the domestic league Performance stabilization and dai!y work on physica!, tactical, mental and technical periodization Attack Average of tvvo geais per match Repetition of offensive tactics, maximizing number of p!ayers in • the box Defense Less than one goal per match Daily work on defensive tactica! rules Home results More than 15 wins at home Respect for game philosophy, knowledge of team tactics Away results More than 8 wins Know!edge of the opponent 1 st half of the season 40 points Rebuilding of filness in preseason and respecting tactical periodization during in-season 2nd half of the season Performance stabi!ization Training camp during the mid· season break Ranking Off-season Tabfe 14.1: Coffective obfectfves e::::::>, DifferentiMion and individualisatlon •lu" f•h v~ a .. on o , e actual situatlon Adjust tralning objcctives ond thc mesoçycte Before the start of each mesocyde Adjust objectivcs and ambitions Strength· weakMss asscssment t? Fig. 14.9: Layout of a periodization p/an during t/1e seasOll Mothod ZGS 1 FITN ESS 1N SOCCER FITNESS IN SOCCER [ Periodization in soccer Periodization in soccer ./ Divide the season into manageable phases. When dividing up the season, account has to be taken of: ° Co1npetition schedule. It goes without saying that the competition schedule "'o ~ o N e o m o • determines the periodization structure. There are, in general, five or six periods (macrocycles) in a soccer season: - Preseason - First half of the in-season - Mid-season - Second half of the in-season - Play-offs - Off-season ° Competih'on fonnula. A competition formula determines the amount of interest that can be devoted to particular mesocycles. For exarnple, a play-off formula or group phase in a cup or European competition will influence the way the season is planned. 0 Availability of training facilitíes. The availability of practice pitches or fitness rooms is important when planning and preparing for periodization, especially for youth teams. 0 Availabílity of players. Factors such as school, work, and playing with the national team also need to be taken into consideration. o Training camps. Planning a training camp is an important decision. The sudden increase in load can cause overload injuries. The ideal time to plan a training camp is in the third week of preseason and during the mid-season break. o Climate. Weather conditions like cold, heat and humidity can influence the training plan. 0 Opponents. During in-season, the microcycles are planned according to the matches. The strength of an opponent can influence the structure of the microcycle. m ""' o E ro !!! "' The season is subsequently organized into macrocycles, mesocycles and microcycles. Y Setting up the first draft of the season plan After structuring the season into manageable periods, the content of the various cycles is determined based on the expected status (i.e., physical, tactical, technical and mental) of the players. m N Y Assessing the current situation This step is repeated before the start of each mesocycle. Time should be spent evaluating the previous mesocycle and planning the next one. This is done based on the following analysis: o Schedule: What games are to be played? How many days are there between matches? 0 Tests and questionnaires: Tests can be included during the season (e.g., HR test, 4' test, submaximal Yo-Yo test) to monitor how the players' fitness levels are developing (actual value). 0 Opponents: Who are the opponents in the coming weeks? o Injuries and availability of players: Injuries can affect the planning of a mesocycle. zsg FITNESS IN SOCCER 1 FITNESS IN SOCCER Periodization ín soccer 2701 Periodization in soccer ./ Adjusting objectives and ambitions Based on the preceding analysis, the objectives and ambitions are adjusted for both individuals and the group. ./ Conducting a strength-1-veakness analysis of the group and individuais Strength-weakness assessments, which must be performed as part of any strategic planning process, are made for the team and each player. Based on this analysis, a personal development plan is drawn up for each player and adapted where necessary. ./ Adjusting the training objectives and methods in the mesocycle for the group Training objectives and methods are adapted based on the current situation. ./ Differentiation and individual periodization The new mesocycle is adapted to individuals. The training plan is planned in advance, but individual periodization strategies are adjusted as necessary based on evaluations by the staff, as well as performance feedback from the athletes regarding perceived fatigue. REFERENCES 1\nganrd, P. and Andcn;cn,J.L., 2010. Effocts of st..,ngth training on cndurancc capncily in lop·lcwl cndurance a~llcl"1i. Scand j Mcd S · ci Sports, 20(SuppL 2), pp.39.-47. ' A~tiaincn,J.P., Hui mi, J.l.; Kraemc:, W.J,, Lc_hti, M., Pabrincn, A., Mero, A.A., Karnvlrla, L, Sillan- paa, E,, Sclannc, H.,Alcn, M., Komul«1~c"':' J., Kovanc_n, Nyman, K. ~nd Hiikkinen, K., 2009. 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Gc gley, ~·<;., 2009. Compari~on of \wo lowc«lmdy modcs of mdurancc trnining on lower·body ~t..,ngth dcvdopmcnt whilc conrur"'nl!y tru.mmg. J, Strcngth Cond. R"1i., 23(3), pp.979-937 Gl~w.<tcki, S.P:,_ ~fartm, S.E., Maurcr, i\., Back, W., G=n, H.J., and Crouoc, S.F., 200·1. Effccts of rcoiot,1ncc, cndurilncc, and conrurrcnt cxcrme on lrn1mng outcomcs in mcn. Mcd.Sd. Sport Excrc., 36(12), pp.2119-2127. Grndiam, J., 2002. PcriodizallOn rer,çnrch nnd cxamplc applic.1tion. St..,nglh Cond j, 24(6), pp.62-70. H'""'"' D., 1974. Training~lchrc. Bcrlin: Sportvcrlag. Hawlcy, J.A., 2009. Molecular rcsponscs to strcngth and cnduranU' training: tire thcy incompatibld ApplPh)'"iol Nutr Mct b 34(3) ·' " , • pp.355-361. Hoff, J. and Hdgcrud. )., 200·1. Endurnnce and St..,ngth Trnining for Soccer Playeru. Physiological Considcrations Sports M ·d 3·1(3) pp.165-J8{). L C ' • ja\.:ovlcl', N.N., 1977. Sportbiochemic. Leipzig: Bnrth Vcrlag. Kar~virt_n, L., Hákkincn, K., Kuuhitncn, Arija·lllnzquet, A., Sillanpoa, E., Rinkinen, N. and Hiikkincn, A., 2011. Individuol n.-;ponllcs l?contbrncd cndurnnccand st..,ngth trmning lnoldcr adulls. Mcd Sei Sports Excrc, 43(3), pp.48-l-\!}(l. Kotov, 1917. OlympicSp-0rl. Kracmcr, W.J,, 200.J. Roundlablc Disrus:;ion: Pcriodization ofTrajning Part 1. Nationnl Slrcngth and Conditioning A••odntin )• m•I 26, pp.50.69. "" vll vU " ' Fle~k. SUMMARY Periodization is a planned variation in training methods on a cyclic or periodic basis. The soccer season should be periodized in such a way that allows fatigue leveis to be attenuated appropriately and ensures that team performance is stabilized across the competitive season at as high a levei as possible. In order to achieve these aims, periods of Ioading,. recovery, and tapering have to be sensibly arranged. Due to the congested fixture list in elite soccer, there is very little time for soccer players to train between games, as many training sessions are aimed at either recovering from match play or tapering in preparation for the next match. Therefore, it is time efficient if players train tactical principies while maintaining/improving their physical condition or even during recovery and tapering sessions. This concept of tactical periodization is discussed in more detail in the next chapter. ?·' K'.ª"".'cr, W.J: "":d Flcck, S.]., 2007. Oplimizing Stn:mgth Training D.,,;igning Nonlincar Pcriodiz.to!ion Workouls. Champalgn, JL: Humun Kmctics Pubhshmg. ::,,~:;:~'. C., Abrahams, H.M., Bactzncr, W., 1930. Athlctik: Ein Handbuch der lcbt.>nswichti. gcn Lcibcsübungcn, München: LF. Kusnezow, W.W., 1972. Kraft"orbc"'ilung. Bcrlin: Sp-0rl"crlag. Lctunov, 1950. Rcflcctions on lhe Syotematic Fomlulalion ofTraining. Sovietskii Sport, 125. 1'fac0ougall, l:D., Salc, D.G.: Moroz, l-~·: Eldcr, G,C., Sutton, J.R. and Howald, H., 19i9. Milochondrial volume dcnsity ln humun okclclnl mundc lollowing hcal'y rcomtancc trammg. Mcd Sd Sporls, 11(2), pp.IM-6. Mnlvejcv, L.P., 1974. Pcriodisicrung dcsspo<llichcn Training•. Bcrlin: Barlcls & Wcmitz, Mulvc1ev, L.P., 1977. Fundamentahofsp<.>rts lraining (Russiant Moscow; Rzkulturn i Spor~ Matvc1cv, LP., 1981. Fundamcntalsof sports lraining jEnr;li~h lranslolion of thc reviscd Ru%ian cdition]. Mo~cow: Progrcss Publishcru. M<:Gawlcj; K. and Andcl'&.wn, P.l., 2013. TI1c Ordcr of Concurrent Traininr; Does not Affoct SocCl)r-Rcl,1tcd Pcrformnncc AdaptalioM. !ntj Sporl.<; Mcd, 34(11), pp.983-90. Morton, R.H-, 1997. Modclling lrnining and ovcrtraining. / Sporls Sei, 15, pp.335-40. N~tton, V., 1973. Thc Chrono!ogy ofGalcn's fa>rly Cnrccr. Classical Qunrlcrly, 23(1), pp.153-171. Pl~sk, S.S. and Stone, M.H.'. 20?3. l'c_rio~izat~on _Str~tcgies. N~ti~nnl Strcngth & Conditionlng Joumal, 25, pp.19-37. ~~~·~iÍ.2004. Roundtabk D1sru%ton. Permd1zotion of Traimng l'art L National St..,ngth and Conditioning As.,0ci,1tion Joumal, 26, l'n.'S~C§,j., De Lima, C., Frollini, A.íl., Donatto, F.F. and Conte, M., 2009. Compariwn oflincar and rc\'C!"'oC linear periodiz.ltion effccts on mo~m."lslnmglh,1nd body composition. J St..,ngth Cond Res. 23{11 pp.266-27.J. Po.hquin, C., 1997. Thc p<.>liquin prindplcr.: Succe,;.'\ful methods for strcngth and mass dc•·clopmcnt. Nopa Ci\: Daylon Writcr'~Group !'riCI), M. and Moss, P., 2007. The cffccls of work: Rest durndon on physiologirn! and pcrccplual =ro~ during intcrmittcnÍ excn:i~~ and pcr/annance. J Sp-0rls Sd, 25(H), pp.1613-1621. Rhca, M.R., 2()0.l. Dctermining thc magnitude of trcatmcnl cffccts in otrcngth \rainlng rcscarch through lhe use of thc clfc<:t r.izc. J St..,ngth Cond Rcs, 18(·1), pp.918-920. Rhco. "''.·R., Phlllips, W.T., Burkelt, LN., Stonc, W.J., Boll, S.ll., Alvar, B.A. nnd Thomas, A.B., 2003. A comparison oi ]lncar and daily undulatmg periodizcd progrnmo withcquatcd \'O lume and intcruHy for locitl muscular endurance, / Strcngth Cund RCi>, 17, pp.32·87. 271 FITNESS IN SOCCER The Tactical Periodization Model FITNESS IN SOCCER 212 j Periodization in soccer Schncider, V., Arnold, B., 11-farlin, K., Bcll, D. and Crockcr, P.. 1998. Detrnjning dfoct in collcgc foolbal! players during thc comp.;:titiw wason. Strength Cond J, 12{1), ppA2-15. Siff, M.C., 200J. Supcrtralnlng 6th Ed. Dcnvcr: Supcrtraining ln"titutc. S!camakcr, R. 198?. Scrious trainins for,;eriour. alhlcl...,,. Champaign, IL' Ldourc Presr.. Starischk.l, S., 1983. Triliningsplanung. Schomdorf: Hofmann. Stolen, T., Chamari, K., Ca5tni;nn, C. nnd Wisloff, U., 2005. Phyoiology of socrer: An updntc. Sporu Mcd, 35(6), pp.501-536. Stonc, M.H.,O'Bryant, H.S., Sdiilling. 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Quantifying test-rdcst reliabi!ity uoing thc intrada,;.s oorrelíltion cocfficicnt and thc SEM. J Strcngth Cond Rcs, 19(1), pp.231-2-10. \Vilks, R., 1995. Trainini; thcory and strcngth training. Strength nnd Conditioning ooach, 3, pp.10-15. Wfüon, J.1'.L Marin, P.J., RhN, M.R., WiJ:;on, S.M.C., Locnnckc, J.P. and Andcrson, J.C., 2012. Concurnmt tmining: A mcta-ana!ysio cxamining intcrfcrencc of acrobk nnd resistam:<' cxcrdsc. J Strcngth Cond Rco, 26(8), pp.2293·2307. Ziwiornky, V.M., 19n. Die kfüperlichcn Eigenschnftcn dcsSport!crs. Dcrlin: Bartcl5 & Wcmitz. Zil5iornky, V.M., 1995. Scien<:<' and prnctic<' of "trength training. Champign, JL: Human Kinctic;. 15 THE TACTICAL PERIODIZATION MODEL <UNDERSTANDING THE GAME'S DEMANDS TD ENHANCE SOCCER PERFORMANCE) Juan Luis Delgado-Bordonau~ Alberto Mendez-Villanueva 15.1 INTRODUCTION We accept that tlle football training niethodologies have been evolving and i111proving greatly over ti1ne, but their origin renzains the sanze: nzethodologies which approac11 different aspects of the ga111e in analytical and decontextualized fonns (Ta111arit, 2007). ln an attempt to simplify the complexity inherent in any human activity, sport-training methodologies, like most other sciences, have used the "Cartesian" way of thinking. Consequently, they suffered from a fragmentation of its various dimensions (e.g., physical, technical, tactical and psychological). From this perspective, these factors are first trained separately and combined later on when applied in competition. Training methods have also been characterized by the division of the season into severa} periods, and the periodization of these methods was structured so "peak performance" would be reached at major competitions. To do this, these training methods gave priority to the "physical" factors, because the concept of "performance" appeared to be closely related to a set of adaptive biological changes (functional and morphological) that occurs in the body. Training methods were based upon the isolation of performance factors, and training was organized through analytical approaches where decision-making processes played a secondary role. ln contrast to these analytical training approaches, the so-called integrated training method has gained momentum in team SJ?orts. This is where physical, technical and tactical aspects are developed in combination. ln short, integrated training prometes a resemblance between competition demands and training activities, but it does not address the contextual and specific features of all the game elements. Its levei of specificity therefore only relates to the sport itself and not to a certain way of play (game model). J zn 274 1 FITNESS IN SOCCER The Tactical Periodization Model In this regard, Mourinho (quoted by Amieiro et al., 2006) said, "For me, things are very clear. There is a traditional analytical-training approach; there is the integrated training system that is clone with ball, but where fundamental concerns are not very different from traditional practice; and there is my way of training (called 'tactical periodization') that has nothing to do with the other two. The only difference between traditional training and integrated training is that in the latter, players are mentally deceived by giving them a ball. But training consequences are exactly the sarne as the traditional training." As highlighted by Guilherme Oliveira (2004), integrated training does not regard the tactical dimension to be the driver of the entire training process, so the game model is not used as a reference. Thus, the "integrated" approach becomes less specific than tactical periodization, because the decisions taken by the players at different times are not regulated and coordinated by a common language (i.e., the game model). It does not allow the players to think in harmony and have the optimal collective behavior the coach wants to see displayed at every moment of the game. ln a similar vein, Carvalhal (cited in Amieiro et al., 2006) states, "There are two types of work >vith the ball: integrated (i.e., integrated training) and systemic (i.e., tactical periodization). In the first, the ball is present, but it is not subordinate to the game model. We advocate another kind of training in which the ball is present from the first day in arder to create a model that is the way we want to play (collectively and individually). Thus, the team is being organized to play from the first day, and at the sarne time, performance is being modeled at all leveis: physical, technical and psychological. We pay attention to all dimensions, but which coordinates all of them (physical, technical and psychological) is the tactical work." 15.2 TACTICAL PERIODIZATION: A NEW SOCCER TRAINING APPROACH "We ca11 differentiate a1nong traditional-analytical training tvhere the different factors are trained in isolation. There is the so-called 'integrated training,' which uses the ball, but the f11nda1nental concerns are not very different fi·o1n tlze traditional one, and there is my ivay of training, which is called Tactical Periodization. It lms nothing to do ivith the previous two, even though 1nany people 1night think so." (Mourinho,/. in Gaiteiro, 2006) ln recentyears, along with the ever-changing soccer demands, we have seen a trend toward a change in training concepts and methodologies, representing a break with the past. Perhaps the biggest rupture from traditional soccer-training methods has taken place in Portugal and Spain. One of the most contemporary training approaches in soccer is the so-called Tactical Periodization method. The Tactical Periodization method was developed by Vitór Frade, a lecturer at the University of Porto (Portugal) who is responsible for Porto FC's coaching methodology. Several top-levei coaches, such as Jose Mourinho, are also applying this method. Explained in a simplistic manner, the main methodological and pedagogical principie behind Tactical Periodization is that the soccer game has to be "trained/learned" with respect to its logical structure. For Tactical Periodization, the "logical structure" of the game revolves around the four moments of the game (see Figure 15.1). Accordingly, at least one of these four moments of the game has to be accommodated in every single training exercise, following the principie of specificity. FITNESS IN SOCCER The Tactical Periodization Model Fig. 15. 1: Moments of the soccer game. According to Tactical Periodization, the tactical dimension is not reduced to a system of play or team shape (spatial organization). As stated by Mourinho (2002), "Tactics is understood as a well-defined set of principles of play, both for attack and defense (and their transitions) in accordance with the way of play desired by the coach. The ultimate goal is to 'organize' the 'chaos."' This periodization is called "tactical" because, according to Frade (2003), "The game's expression is tactical: the way we want to play." Tactical Periodization aims to make an operational game model. Every training exercise is contextualized with reference to a global framework: the game model. Thus, the game model and its principies guide the training process from the very beginning. Tactical Periodization understands that training has to "model" the game through specific exercises that include ali the game principies relevant for each coach. As Gomes (2006) points out, the specificity of an exercise not only covers its structural and temporal features-the coach should also direct players' attention to behaviors he or she wants to develop. Thus, Tactical Periodization considers that specificity needs to be directed not only to the design of the exercise itself but also to the coach's intervention (e.g., feedback). Consequently, training will guide the players into a pattern of play, aiming to develop a collective and individual identity. Frade (2004) stated, "The game is an ongoing phenomenon; its construction is created by the habits we want to see happening in the field, which are acquired throughout the action (training)." Every game action, regardless of which of the four moments of the game it might happen at, involves a decision (tactical dimension) and an action ar motor skill (technical dimension) that requires a particular movement (physiological dimension), and it is directed by volitional and emotional states (psychological dimension) (Oliveira, 2004). A good perfonner (i.e., a good soccer player) is, first and foremost, an individual able to select the most appropriate response to different game scenarios, and these actions are always determined by a tactical context 1 275 276 FITNESS IN SOCCER The Tactical Periodization Model FITNESS IN SOCCER 1 The Tactica/ Periodization Model (Garganta and Pinto, 1998). Accordingly, the tactical dimension should be the dominant training component The tactical dimension leads the orders to achieve the targeted goals. For example, the concept of "speed" would change to "relative speed," because a player sometimes needs to be second to be tactically "effective" in a given soccer situation. However, the tactical dimension does not exist by itself-it only makes sense when it occurs through the interaction of the other dimensions (Oliveira, 2004). This implies that the tactical, technical, physiological and psychological elements are never trained independently. Everything is included, with the main concern being that every exercise is organized around at least one of the four moments of the game and the tactical principles of play. 15.3 GAME MODEL "To 1ne, the most únportant aspect in my tea1ns ís to have a defined ga111e 1nodel, a set of principies tlmt provides orga11izatio11. Therefore, since the first day, our attention is directed to adlieve that." (Mourinho,]., in Gaiteiro, 2006) Models are creations that are based on interpretations of reality (Le Moigne, 1990). Modeling results from the need to understand the complex interactions between the different elements of a system. ln the game of socce1~ there are specific features, such as players' decision making. Those decisions cannot be coincidental, so they have to be based on certain principles, making the team's actions follow an internal logic. While constructing the game model for the team, coaches should consider several factors that operate within a given specific context, with each factor being equally important (Figure 15.2). Fig. 15.2: Factors that influence designing and building upa game mode/. (Adapted from Oliveira, G. 2007) A key aspect in building a game model relates to the style of play the coach wants to see represented in each of the different moments of the game and the interrelationships between them. It is imperative for players to know exactly what they have to do at every moment of the game. There are certain tactical behaviors and patterns the coach wants to be revealed during the game, such as collective (i.e., the whole team), inter-sectorial (e.g., defenders and midfielders), sectorial (e.g., defenders), and individual actions (Figure 15.3). Thus, the model consists of principies, sub-principles, and sub-sub-principies of play, all of which are articulated with each other, representing the different moments of the game (Oliveira, 2003). The compatibility of the different principies and moments of the game is particularly important, because behaviors can sometimes be incompatible. These behaviors and patterns, when articulated, expressa collective dynamic behavior and reveal a certain playing identity, which could be called a functional organization. The structural organization is ho\V the team is placed on the field-it is usually called the system of play (e.g., 1-5-3-2 or 1-4-3-3). Although the structure only represents a fixed spatial shape, it can have an important role in promoting or constraining desired ·behavior. For instance, to have good leveis of bali possession and circulation, it seems important for players to constantly create diagonals and "diamonds" among themselves. As such, some structural organizations can enhance these behaviors more than others (e.g., structures with a high number of lines, both transversal and longitudinal). Individual Levei Sectorial Levei Jntersectorial Levei Collective Levei Fig. 15.3: Tactical relationship leveis. l zn 278 1 FITNESS IN SOCCER FITNESS IN SOCCER 1 The Tactica/ Periodization ModeJ Regarding the players, the game model should highlight and enhance their best features and capabilities. It is essential for the coach to acquire, as soon as possible, a deep knowledge of the players, especially their levei of game understanding, because he or she will interpret the behaviors that lead to the team playing in a certain way. ln this regard, Frade (2003) points out that the game "has to be bom first in the players' minds." Therefore, it is crucial for the coach to use strategies that let the players recognize the importance of certain behaviors, because their convictions are also vital in developing the game model. Consequently, the construction of the game model arises through a process that operates between the coach, players and the team itself. The coach's constant awareness about what he or she wants to happen, both in collective and individual terms, and what is actually happening in the game should be the driver of the training process. However, it is important to understand that the definition and creation of a clear game model should not be perceived as something that will require players to act as robots always following a predefined plan. On the contrary, the main purpose of having a clear game model is to reduce players' uncertainty, and this should give players more time to express their creativity. The structure and expectations of the club or federation are also important aspects in creating a game model. Coaching a team that can only train two or three times a •veek and coaching ateam that can train five times are obviously different tasks. The scope for improvement, both collectively and individually, is also different. The culture of the countries and clubs has also to be taken into account when creating a game model. 15.4 PRINCIPLES OF PLAY AND GAME MODEL "We exercise our ga1ne 1110del; we exercise our principies and sub-principies oj play. The players have to adapt their ídeas through a co1111non goal in arder to establish the sa111e behavioral language. We rvork exclusively on ga1ne situatio11s related to our ivay of play. We do our weekly planning to crente habits in arder to 1naintain high leveis of perfornzance, 1vhic11 often translates into 'playing well'." (Mourinho, 2005) The fundamental principies of play, according to Carlos Queiroz (1983), are "the rules which help the players to run and to coordinate their activities (individually and collectively) during the moments of the game." Therefore, they are rules of action that support the basic objectives of soccer. According to the sarne author, these fundamental principies are composed of hvo kinds of principie: the general principies, which are the general behavioral requirements, and the specific principies, which are related to the attacking and defensive moments. Both general and specific principies are inherent to the game, regardless of the way or style of play. Specific principies include attacking principies (e.g., penetration, depth, mobility, width and space) and defending principies (e.g., delay, depth, balance, concentration and composure). General principies include avoiding outnumbered situations, avoiding parity, and creating overloads. However, there are many different ways to perform a given general or specific principie. Therefore, Guillerme Oliveira (2003) states we can add a third type of principie of play: the specific principies of the game model. The Tactical PeriodizaHon Model The specific principies of the game model refer to a set of match-play patterns the coach wants the team to adopt at any of the four moments of the game. In simple terms, it's how the coach wants the team to play, according to his or her conception of the game. Given the high unpredictability that exists during a soccer match, the coach has to try to create predictability through a process of preparation, planning and training. Accordingly, every training session is designed to be as significant as possible to the coach' s game model. The systematic repetition (i.e., training) of the tactical principles of play should allow the players to transform the coach' s desired match-play pattems into habits, which could be defined in lay terms as "shortcuts created by the brain" (McCrone, 2002). The creation of these habits, the main objective of which is to "save time," is only possible when the brain has already experienced the sarne or similar situations and "recorded" them. The work of Haggard and Libet (2001) showed that the brain prepares movement responses long before we are conscious about the execution of the movement. Actions and decisions that are taken daily may seem to be conscious and instantaneous, but they are actually the result of subconscious processes in the brain. Thus, through these "habits," decision and reaction times can be substantially reduced (McCrone, 2002). This method of training intends to prepare players to understand and react faster to every possible game situation. Combined, these principies allow our soccer team to perform certain motor behaw viors and pattems on an individual, sectorial, intersectorial and collective scale. Therefore, these principies are specifically designed according to our own way of play and team identity. Obviously, these principies should always be in accord with the fundamental principies of play. The specific principies of the game model can be manifested at different leveis of complexity. Tactical Periodization uses the following nomenclature to hierarchically organize them: 0 o 0 Main principies of play: related to collective behaviors. Sub-principies of play: related to intersectorial and sectorial behaviors. Sub-subwprinciples of play: related to individual behaviors. 279 280 1 FITNESS IN SOCCER The Tactical Periadization Model Thus, the model consists of game principles, sub-principies and sub-sub-principies that represent the different moments of the game. When they are articulated with each other, they express a functional organization embodying the identity of the team (Oliveira, 2003). In this sense, it is essential the coach knows well what he or she wants to see happening at each moment of the game. When defined, the principies, sub-principies and sub-sub-principies should be clearly exposed to the players, so everyone can clearly understand the way the team wants to play. However, making all the players understand the sarne thing and getting them to act with the sarne objective at the sarne time is not an easy task, and this takes time. Therefore, it is essential for players to have the will to learn, but it is also crucial for the coach to convince the players to work to\vard a common project and establish a common language between all team members. At this point, it is worth mentioning that the game principles are "open rules," so they merely guide the players to act in a coordinated manner while always respecting players' freedom and creativity. 15.5 TACTICAL PERIODIZATION: METHODOLOGICAL PRJNCIPLES To make an operational game model, Tactical Periodization has defined and developed its own and unique methodological (pedagogical) principies (Figure 15.4). FITNESS IN SOCCER 1 The Tactical Periodization Model 15.5.1 Principie of Specificity "For n1e, training 111eans to train in specificity. That is, to crente exercises that allow 1ne to exacerbate 1ny principies of play." (Mourinho, in Anzieiro et al, 2006). This is arguably the most important principie of Tactical Periodization. Specificity arises when there is a permanent relationship between all the dimensions of the game and the training exercises are specifically representative of the desired game model (style of play). Therefore, the concept of specificity directs and leads the "whole" training process. ln this regard, Vitor Frade (in Silva, 1998), affirms that regardless of a training exercise's features (e.g., with more ar fewer players, larger or smaller spaces, etc.), it should always be articulated in a way that allows our principles of play to be learned and transferred to competition. However, every exercise is just "potentially specific." The fulfillment of the principie of specificity will be only truly achieved if during training, players understand the aims and objectives of the exercise and maintain high levels of concentration. The coach's intervention should also be appropriate (Oliveira, 2008). Then, specificity is related to the capacity to make operational the principles of play and their respective sub-principies. Thus, according to Tactical Períodization, the principie of specificity should also lead the interactive intervention between the exercise, the players and the coach. 15.5.2 Principie of making tactical principies of play operational (conditioned practices) "One of the 11zost difftcult questions is how to ntake operational our sti;le of play. We try to achieve that by creating exercises ivhere ive are able to e1nbrace all the dhnensions (technical, tactícal, physícal and 111ental), but never forgetting our first concern: to enhance a given principie of play of our ga111e 111odel." (Mourinho,]. in Gaiteiro, 2006) Fig. 15.4: Methodological principies of Tactica/ Periodization. When we observe a team, we find it tends to exhibit a dynamic behavior that constitutes its identity, explaining some patterns of action. To transform these pattems into practice, every training exercise must be performed in close relationship with our style of play (game model) and the concept of specificity. These references should always be present in our daily work in arder to provide specific adaptations and tactical kno\vledge. If a proposed exercise is designed without considering our style of play, the promoted adaptations can have adverse effects and interfere with the acquisition of the desired specific knowledge. It is crucial for exercises to represent the way we want to play and the unpredictability inherent in the game. This implies that each of the proposed exercises has to bring forward something the players cannot central. If the game is nonlinear, the training exercises, even though they are less complex, should also be nonlinear and exclude any direct cause-and-effect relationship. The coach's intervention plays a key role when conducting an exercise, because this positively or negatively catalyzes its specificity. It is also important to note that the structural and functional configuration of the exercises is crucial in order to comply >vith the specificity of the game. This means there are exercises that, because of their structure, promote functionality (e.g., the 281 282 1 FITNESS IN SOCCER The Tactical Periodization Model FITNESS IN SOCCER The Tactical Periodization Model acquisition of subconscious behaviors). Alternatively, there are exercises that have the exact sarne aim, the sarne number of players, and the sarne field dimensions, but the distribution (i.e., structure) of the players in the field is di:fferent to what would be required in a game (e.g., central defenders training in a different playing position and role). This can consequently promote inadequate subconscious behaviors and tactical knowledge. As stated by Mourinho (Amieiro et aL, 2006), "Training is only worthwhile when it lets you make your ideas and principies operational." Thus, coaches have to find exercises to guide their teams to do what they want them to do in a game. It seems intuitive that when the aim is to teach or improve a particular principie or sub-principie of our game model, the best way to do it is to create appropriate exercises. Then, if we are interested in certain behaviors related to a given principie of play, we should make them appear more often in the exercise. As such, the requested behavior has to appear much more frequently than it would during a formal game, because this enables players to create multiple mental images about the desired target. Thus, the configuration of the exercise (i.e., playing space, number of players, roles, objectives, etc.) must promete the appearance of the required behavior(s), and this is called "conditioned practice." For example, setting up an exercise where a team's defensive sector is under-loaded and constantly defending will cause behaviors related to defensive organization to continuously emerge. There will then be ample opportunities for coaches and players to "shape" these behaviors. 15.5.3 Principie of disassembly and hierarchical organization of principies of play. "I ivrote a doc111nent that is never going to be published. It is niy 'training dossier,' zvhere I keep all 1ny training guidelines. That is, all my training goals and the tvay to achieve the1n through 1ny rnethodological principies. If I would have to na1ne this docinnent, its title would be: The evolution of n1y trainilzg concepts." (Mourinho,/. in Lourenço, L. & Ilharco, 2007) Principles of play are very complex concepts because they involve severa! variables that are intrinsically and inextricably related. This is why Tactical Periodization breaks them down to reduce their complexity. Thus, the principies of play are subdivided into sub-principies, and these are further fragmented into sub-sub-principies. The aim is to make them more understandable for the players and therefore help their assimilation. This process of disassembling the principles of play has to be done very carefully, always respecting the style of play (game model) and the wholeness of the game (systemic vision). Each specific principie of the game model is directly related to one of the four moments of the game (see Figure 15.6 for an example). Equal value is not awarded to ali the principles of play, so there is a hierarchical organization. The importance of each principie during the training process is directly related to the intended game model. Some principies are more important and valued than others in terms of what is intended. A coach's ability to articulate all the principles that conform to his or her game model will determine the team's "DNA," which is basically the coach's conception about the game Fig. 15.5: Principie of making principies of play operationa/. (Tamarit, 2007). Fig. 15.6: Example of the Disassembly of a Principie of Play. Adapted from Gomes, M. (2006) 1 283 284 FITNESS IN SOCCER The Tactical Periodization Model 1 FITNESS IN SOCCER The Tactical Periodization Model 15.5.4 Principie of horizontal alternation in specificity "Our daily concerns are directed to 111ake operational our ga1ne nzodel. However, the structure of the training session and w1iat to do eaclz day is nat only related to the tactical objectives, but also roith the physícal Jitness co1nponent ta be prioritized." (Mourinho, in Atníeiro et al., 2006) This principle relates to the need to maintain a regular and fixed weekly pattem that respects the balance between training and recovery demands (Amieiro et al., 2006). The Principle of Horizontal Alternation in Specificity highlights the importance and relevance that Tactical Periodization gives to the physical/ physiological dimension, contrary to the common and unfounded misconception that this dimension is forgotten and untrained. In a simplistic manner, the three main training (acquisition) days in the week altemate '\vhich physical-fitness component to promete (assuming the team is playing one game per week) (Figure 15.7). This is dane by prioritizing strength (first acquisition day), endurance (second acquisition day) and speed (third acquisition day) factors. Thus, no two days within a given week demand the sarne physical-fitness component. The main goal is to avoid a large amount of stress on the sarne physical-fitness component, giving the body time to recover and consequently minimizing fatigue. Recovery will take place, at least partly, by switching the dominant physical-fitness component and its associated neuromuscular, metabolic and morphological underlying factors throughout the week. This altemation in the physical-fitness components to be prioritized is said to occur horizontally along the weekly pattem, rather than between exercises within the sarne training session (vertically). The tactical goals and objectives of each training day can obviously vary in accordance with the specific needs of the team, but the physical-fitness component being prioritized each day of the week will remain the sarne. Thus, it can be said that for Tactical Periodization, the physiological dimension provides the biological framework where the soccer-specific training/ recovery continuum lays. SubOFF prlncfpfos Subprlncipfes Sf'EEO SUNOAY MONOAY RECOVii:RY TUESDAY WEDNESDAY THURSDAY FRIDAY SATUROAY SUNOAY REGOvt!RYOAY RECOVERY OAYS Subprincfp/<!s SPEEO Sub· OFF principies Sub· SUNOAY MONDAY TUESOAY Sub-subprincipies prlncfpfes Sf'EEO ACTIVATION RECOVER'f SUNDAY MONOAY TUESOAY Fig. 15. 7: Standard weekfy pattern. (Adapted from Gomes, 2006) WEDNESOAY THURSDAY FRIDAY SATURDAY SUNOAY WEDNESOAY THURSDAY FR!DAY ACTIVATfON SATURDAY SUNOAY 1 285 286 FITNESS IN SOCCER The Tactical Periodization Model 1 FITNESS IN SOCCER The Tactica/ Periodization Model The specific training contents {i.e., exercises) for each week arise from the continuous interaction between the game model, the performance of the team in their previous game, and the characteristics of the upcoming opponent. The game model acts as a reference to analyze previous game performance. Thus, positive and negative aspects can be identified, and any potential issues the team may face in the next game can be anticipated. Accordingly, the training exercises should take into account any problems the team showed in the previous game, as well as those they will probably face in the upcoming game (Figure 15.8). Fig. 15.8: Factors to take into account when setting weekly goa/s (Adapted from Gomes, M. 2006) 15.5.5 Principie of tactical fatigue and tactical concentration "Concentration needs to be trained. It can be done by training according to a specific philosophy. I cannot dissociate training intensity fro1n tlze concept of concentration. When I say that football is rnade by actions of high intensif:1.;, I also refer to the need for pennanent concentration; it is únplicit to the ga1ne." (Mourinho, in A1nieiro et al, 2006) Soccer players' peak performance requires a constant tactical thinking, both in game and in training. Players need to always concentrate. The development of a tactical attitude requires an attitude that can think and decide quickly. High levels of concentration, from the first to the last minute of the game, are an essential requirement. Therefore, "intensity" is not an intangible concept-it is directly related to the principies and sub-principies of play that, when trained through well-designed exercises, will direct players' future actions and thoughts. The more variables that players need to analyze during the execution of training exercises, the more demanding and intense the sítuation will be (Frade, 2003). The intensity should be always maximal but relative, because it relates to the actions performed on a given training session. It will differ from day to day because the complexities of training sessions also vary from day to day, dragging with it the other dimensions of the game (Figure 15.9). We can exemplify the concept of relative maximum intensity as follows. If the team played on Sunday, the player is unlikely to be fully recovered (both physically and mentally / emotionally) by Tuesday. To overcome all the challenges the Tuesday training session can impose, the player should work at his or her maximum intensity of concentration. That maximum intensity, however, will not be enough to overcome the increased complexity (and intensity) that the training tasks will demand, for instance, on Wednesday and Thursday (because the player's recovery status has also improved). Therefore, in Tactical Periodization, the intensity is always maximal in terms of concentration, but it is relative to a player's recovery and readiness to train. The higher the level of concentration during the training exercises, the less chance there is of making mistakes. A high concentration provides a higher degree of leaming, so coaches should always seek the maximum concentration during training. Fig. 15.9: Factors to manage exercise compfexity. 1 287 zss I FITNESS IN SOCCER The Tactical Periodízation Model 15.5.6 Principie of complex progression FITNESS IN SOCCER The Tactical Periodization Model 15.5.7 Principie of performance stabilization "Since the very beginning, the principies and sub-principies of our ga1ne model are prioritized through a set of exercises. But the best way to convey our ideas is by loivering the co1nplexity thro11glz tactical, conditioned s1nall-sided ga1nes." (Mourinho,]. in Fernandes, 2003). "Ido not want niy tea1n to have peaks i11 pe1fonna11ce. Ido not ivant 111y tea111 to srving pe1fonnance. Rather than that, I prefer to always keep high leveis of performance. Tlzis is because to 111e there are no períods or ganies that are 1nore inzportant than others." (Mourinho, in Anzieiro et al., 2006) This principie relates to the hierarchical organization of the principies and sub-principles of play. It has nothing to do with a general-to-specific progression, from volume to intensity, or such like. For Tactical Periodization, the concept of progression is built around the acquisition of a certain way of playing. This progression appears at three different levels of complexity: during the season, throughout the week (taking into account the previous game and the upcoming one), and finally during each training session, thus becoming a complex progression where each level is related to the other. According to Frade (2004), during the early stages of the training season, we should introduce the general principles of play (related to the four moments of the game: defensive organization, offensive organization, transition defense-attack, and transition attack-defense). If players know and "can explain" when to apply the principies of play relative to each moment, it will be easier for them to assimilate the specific principles that each coach has in his ar her game model. ln a second phase, we should work on the specific principies of "our" game model. At this stage, we can distinguish two moments, with the first being the defensive organization of the team, which we will begin to work with. From our point of view, it seems advisable to focus first on the defensive organization, because by having a good defensive organization, the team will gain confidence and consistency, and this allows coaches to progress into other game situations (defending properly to attack even better). ln addition, defending is "easier" than attacking. Coaches can then progress to the more complex behaviors that the offensive organization requires. The transitions are a key aspect of modern soccer, so coaches should try to train them from the very beginning because they will be linked to the team' s defensive and offensive organization. To understand the entire logical structure, the Principie of Complex Progression and the Principie of Horizontal Specificity Alternation should be linked. We refer to a "building up" and "disassembly" of the principies and sub-principies and their hierarchy within the weekly plan and over consecutive weeks, according to the evolution of the players and the team. This methodological principle has two leveis ofplanning thatinteractwitheachother: the short term (i.e., game to game) and the medium-to-long term (i.e., style of play and game model). From a conventional viewpoint, the concept of performance is normally based on a set of quantitative-oriented criteria based essentially on the physiological dimension. Planning and periodization in soccer has to assign vital importance to the concept of "performance stabilization," which derives from the game's long competitive period. From this perspective, "being fit" is to "play well" and "playing well" is to carry out the on-field duties in accordance with the intended game model. Underpinning this concept is that collective and individual performance is the basis of the team's organization, and this is the fundamental objective to be maintained. Thus, what really matters is that a team regularly demonstrates a certain quality of play (despite minar fluctuations) to guarantee consistency in competition. A stable levei of optimal performance is achieved through the implementation and maintenance of the standard weekly plans (Figure 15.10). Thus, over the season, weekly dynamics regarding training content, recovery schemes, and the number and length of training units remain almost invariable. Soccer performance and training cannot be separated from competition and the game. It must be translated in terms of play, a quality instead of quantity approach, always working on offensive and defensive actions and the dynamics that allow the connection of these two moments. By working in such a way, the methodological Princip le of Stabilization is respected. "' MONCAY J\ClWATIOtl rtJl:Czy;m!Y TUE$P/l.Y FR!CAY $'1iJ.ptboí#« ~UllDAY MOH!IAY Svh·•"/).prlo<ip/o "~ Off SUND/l.Y nATUnDAY TIIUMY W~DNeSDJ\Y Tll\llUIOAY FAJl:>AY ~ATilnOAY TIIUDAY W!!DNESDAY TIIU!UP/l.Y FmDllY nATilnD/l.Y SUNO/l.Y Fig. 15. 10: fnteraction between horizontal aftemation and perfonnance stabilization principies. 1 289 FITNESS IN SOCCER The Tactical Periodization Model FITNESS IN SOCCER Macroeycle: Preseason SUMMARY It seems to be the consensus today that the tactical dimension plays an important role in achieving high performance in soccer. As Pinto, J. (1996) states, "It's increasingly assumed the role of tactics as a center and coordinator of the different factors of football performance. Tactical training therefore plays a decisive role in the education and competitive performance of a football player. The development of tactical approaches implies the development of the ability to decide quickly to be able to create solutions. That is, decision-making skills are inextricably connected with the development of tactical knowledge." Thus, it becomes important to consider tactics as the dimension that coordinates the game and training process. The tactical dimension of soccer does not exist by itself; it makes sense only when it occurs through interaction with the other three: the technical, physical and psychological. When developing a periodized training schedule for a soccer team, it can be argued that tactical training should be the dominant and most important dimension of the plan. 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Mourinho,)., 2002. Quero ganhar tiluloc. com um futebnl al"ic!ivo. Revista Drngõ•>s; Ano 16, n"201. Oliveira, J.G., 2003. Entrevir.ta in ). Tawres (2003). "Uma no<;,'\o fund,1mcntal ·a ..~;pccifiddad": o como inve,;tigM a ordem das ucoisM.'" dojogar, uma espécie de ím·Mi.incias de tipo frnct,1!"'. Porto:). Tavares. D•~r.crtaçilo de Licenciatura apn'S\'ntada 11 Faculdade de Desporto da Univcroidadc do Porto. Oliveira, J.G., 200°!. Conhecimento Especifico em Futebnl. Contributos par.1 a definii;Jo de uma matriz diniomic.1 do proce,;so en~ino­ aprcndizngem/ treino do jogo. Porto: J. Guilherme Oliveira. Disscrtaç.io de Mestrodo aprcscnt,1da ~ Faculdade de Desporto da Unívcr.>idadc do Porto. Olivcirn, J.G., 2007. F.C. l'orto: Nu~~;tro MkrocidoScrnana! (Morfocido). VI Clinic FUtbol lla~e Fundación Oe.asuna. Oliveira J.G., 2003: Apontamcntoc. do Curso de Tf\'inado"'" de Futebol UEFAb, Fedcraç,io l'ortogues.1 de Futebol, As:;oci,1<;,'IO Futebol do Porto. Asoociaçao Nacional de T"'inado"'s de Futebol. Porto. Tr.1balhonõo publicado. Pinto,)., 1996.1\ tilctica no futebol; abordagem conceptual e Implicações na formação. ln/. Oliveira & F. Tav,1rec. (Eds), Mtratégi.1 e Tdctica nos jogos Dcoportivm; Colectivos. FCDEF-UP. Queiroz, C., 1986, Eotrutura cOrganlzaç~o dos E:<erdcios deTfl'inoem Futebol. Lisboa' FcderaçJo Portugu~-s.1 de Futebnl. Silva, L, 199S. Rcndlmcn!osuperior no futebol, "sem leoücs"', quais a:; razil•>s? Porto'!.. Silva. Dis>er!~ção de Li<:t."ndat\lra apn.'&l'ntada 11 Fanildade dcCilncias do De~portoc de EducaçJo F!sk,1 da Univeroidade do !'orlo. Tamarit, X., 2007. Que e~ lo Pcriodfr~,ciún Táctica? v;,·enciorel juego pnrn condicionor e! ju.•go. MCSporffi. l'ontevedr,1 1 MACROCYCLE: PRESEASON Jan Van Winckel, Werner Helsen, Kenny McMillan, Paul Brad/ey 16.1 INTRODUCTION ln the previous chapters, we talked about the importance of "fatigue management" and "performance stabilization" throughout the competitive in-season period. ln this chapter, we take a closer look at the preseason macrocycle. The preseason training period is traditionally the period when players complete the most physical work, enabling them to cope with the physiological demands of the competitive season (Bangsbo, 1994). Tae-Seok et al. (2011) examined the physiological loads of programmed "preseason" and "in-season" training in professional soccer players. They concluded that the average physiological loads were higher in preseason than in in-season, anda greater proportion of time was spent exercising at 80-100% of maximum heart rate. During preseason, coaches usually focus on rebuilding fitness (retraining). Adjustments in load are a direct attempt to deliver a training stimulus to promote specific training adaptations (Tae-Seok Jeong et ai., 2011). This contrasts with the goals of training sessions during the competitive season, where emphasis is mainly on maintaining the physical abilities developed during preseason (Bangsbo et aL, 2006). During preseason, the training load can be as high as one or two daily training sessions (90-120 minutes per session) for five days a week (Impellizzeri et al., 2006). Overall, the aerobic capacity of team sport players (e.g., basketball, rugby league and soccer) has been shown to increase throughout the preseason and decrease during the competitive season when using a classical team sport conditioning approach (Stone and Kilding, 2009), Thus, the focus of preseason is usually centered on long-term improvement of physical abilities. For elite teams unfortunately, the emphasis during preseason is increasingly placed on commercial activities, or games are planned to meet sponsorship requirements. Although this may be lucrative in the short term, it could detrimentally affect performance in the longer term. 1291 292 1 FITNESS IN SOCCER FITNESS IN SOCCER Macrocyc/e: Preseason 1293 Macrocycle: Preseason 16.2 PRESEASON TRAINING PRINCIPLES We highlight below some important training principies, which should be taken into consideration when setting upa training plan for the preseason macrocycle. 16.2.1 Aerobic fitness Aerobic fitness is the keystone on which ali further training builds upon. For this reason, aerobic fitness has to be given sufficient attention before other physical abilities can be trained. In an interesting study, Magarey et al. (2013) examined the relationship between preseason fitness testing and injury in elite junior Australian football players. Players with lower levels of aerobic endurance (in a 20m multi-stage shuttle run) were at greater risk of shin/ankle/foot region injuries. The researchers suggest that this is possibly dueto the fact that these players are subject to higher leveis of fatigue ata comparative workload. 16.2.2 Off-season Professional players should maintain aerobic fitness during the off-season to reduce the detraining effect. McMillan et al. (2005) found that aerobic endurance performance increased significantly between the start of the preseason training period and the early weeks of the competitive playing season. They suggested that this may be because players return to preseason training in a detrained state after a summer intermission of several weeks. Bangsbo (1994) found, in contrast with lmpellizeri et al. (2006), no change in V02 mox after a preseason training period in professional soccer players, although the speed at 3 mmol/L blood lactate concentration increased significantly. Impellizeri et al. (2006) suggest that the absence of improvement in V02mnx' as found by Bangsbo, could be dueto the shorter summer break of 2-3 weeks that is typical of professional soccer teams (compared to the longer detraining period for the junior players used in Bangsbo's study). Amigo et al. (1998) studied the effects of weeks of rest on three groups of adolescent soccer players who had undergone systematic training for the previous 11 months. The researchers found a detraining effect: a decrease in the cross-sectional area of type I and type II fibers and a significant decrement in the activities of aerobic enzymes. Bangsbo and Mizuno (1988) found that a relatively short-term training intermission was not enough to cause a significant decrease in V0 2m,,,. but muscle oxidative enzymes did decrease quickly. They suggest that for these two reasons, the levei of physical activity needs to be kept reasonably high during a detraining period to ensure that the mitochondrial enzymatic activity of the players will be as high as it was before the off-season period. 16.2.3 Physiological load / Mechanical load With the arrival of GPS <levices, the understanding of the mechanical load imposed on players has increased enormously. Joints and muscles are subjected to a significant load when changing direction (five times the body weight or higher ), which is why it is best to limit the number of impact training sessions in a microcycle. One of the main goals of preseason training is to improve various physical abilities, and this can be achieved by increasing the physiological load on players while limiting the mechanical load, thus decreasing the chance of injury. However, it is also important during preseason to prepare players for the demands of match play. By monitoring mechanical load during matches using GPS, reference values can be created. Training can then be tailored to ensure players are able to meet their mechanical demands (e.g., number of sprints performed, acceleration and decelerations, the number of high intensity efforts, etc.). 16.2.4 Respect recovery If your club does not have appropriate facilities to allow players to rest and recover between hvo training exercises or sessions, it is advisable to avoid two impact-training sessions per day. Examples: 2 x 75 minute training sessions: • Warm up = 2 x 30 minutes • Active learning time= 2 x 45 minutes 0 Recovery before the next training session: a maximum of four hours after first training session and 16-17 hours after second training session. 1x120 minute training session: • Warm up = 1 x 30 minutes • Active learning time = 1 x 90 minutes • Recovery before the next training session: 24 hours • When training twice a day, alternative training (cross~training principie) can also be included in the program. Rumring, aqua-jogging or cycling can also be used to improve aerobic fitness and create overload without the risk of injury. 16.2.5 Match load / Training load Training should be as match specific as possible. The match itself is therefore good training in principle. After a hard traíning session, however, the body needs time to recover and transform the training work into improved performance, so do not plan any tough training sessions too soon before a match. A match is one of the most difficult types of activity to monitor. Not all players will be active for the entire match, and some players will be used as substitutes. It is therefore necessary to closely monitor matches so that all the players receive the sarne training load. An extra training session the day after a match is not sufficient. The load imposed by a match is often difficult to mimic, and players \vho are not used regularly will have difficulties coping with the dernands of match-play.. 294 1 FITNESS IN SOCCER Macrocycle: Preseason 1295 FITNESS IN SOCCER Macrocycle: Preseason 16.2.6 Workload management As we already read in the earlier chapters, it is important to manage and manipulate fatigue (fatigue management). This can be dane based on objective parameters given by heart rate monitors and GPS <levices, but it can also be based on subjective parameters. During the preseason period, it is important to closely follow the balance between load and load tolerance. This can be done by monitoring the status of players using a simple questionnaire that can be displayed in the changing room (Fig. 16.1). There are also sofhvare applications available now for smartphones and computers that can be used by players to record their stahts, Session RPI scale 1 O Overtraining scale Session RPMF scale 20 RPJ Sca!e 10 What best reflects the intensity of the training? How fatigued are your !eg muscles? Overtraining scare 6 What best reflects your feeling? O: Rest 1: Very, very low intensity 2: Very !ow intensity 3: Moderately intensive 4: Somewhat intensive 5: lntensive 6: O: No fatigue atai 1: O: No pain/fatigue at ali 1: Muscle pain/fatigue 7: Very intensive 8: 9: Maximal intensity 2: 3: 4: 5: Legs feel slightly heavy 6: 10: Legs feel fatigued 15: Legs feel heavy 20: Training is impossible 2: 3: 4: 5: 6: in the morning after waking up Muscle pain/fatigue in between exercises Muscle pain/fatigue at the start of the warm up, but the pain/fatigue fades during warming up Muscle pain/fatigue at the start ofthe training, the muscle pain/fatigue fades during training Muscle pain/fatigue is constantly present during lhe training session Training is no longer possible. Player 1 Player 2 Player3 Fig. 16. 1: Sheet that can be used to monitor subjective fatigue. ( RPI - Rate of Perceived lntensity; RPMF - Rate of Perceived Musc/e Fatigue) As training adaptations are only possible when an overload is created which results in some fatigue accumulation, a player will often feel muscle soreness at the start of the next training session in the preseason phase. Training sessions in soccer are normally completed by the entire team, but because the fitness levels of players can vary significantly, some players will train hard while others undergo a lighter training session. ln order to make sufficient progress for all players, it is therefore important to properly monitor the overload process. One of the golden rules is that a maximum of 25% of the players may be in overtraining scale phase 3 during preseason. 16.2.7 Variation J Monotony The greatest progress is made when there is sufficient variation in the training. Variation also ensures that injuries are prevented. If monotony (the lack of variation in load or intensity) is too high, the likelihood of injury increases. 16.2.8 Finish the training session with an extensive exercise or cool down You often see training sessions ending with an intensive exercise. This gives the coach and players the impression that a satisfactory, intensive training session has been completed. It is important, however, to finish the training session with a cool down. By gently working the major muscle groups, rest products such as lactate are actively processed. A cool down also allows body and muscle temperature, heart rate, and blood pressure to gradually return to resting leveis.Dueto the increase in muscle temperature, the cooling down period is a perfect time to stretch and increase or maintain joint range of movement and flexibility. 16.2.9 Unloading week It is best to incorporate an unloading period of five to eight days into the presea- son phase if possible. This allows dissipation of any accumulated fatigue arising from the first few weeks of preseason training, and also provides time for players to recover from minor injuries. The unloading period is best planned in the third or fourth week. This period also allows the staff to analyze data from heart rate monitors and GPS <levices and consequently adjust the training plan and set new individual goals. 16.2.10 Periodization oftests All too often, physical tests are scheduled during the first week. This is not ideal as players often arrive in a detrained state and are physically unprepared for intensive tests. It may be better, for example, not to carry out any speed or agility tests during the first week of preseason. Instead, the ideal time to conduct these tests is in the fifth phase (intensity phase) of preseason. On the other hand, submaximal aerobic tests can be scheduled in the first microcycle, but maximal tests should be avoided in the first few days. 16.2.11 Individual periodization in off~season Each player needs a minimum of tvvo to three weeks of relative rest after a stres~ sful (both physically and mentally) season. This means that players returning from intemational duty must also be given the sarne time to sufficiently rest and process the physical and neural fatigue. If this break is not respected, it will have consequences for the remainder of the season. 16.2.12 Foreign players Foreign players often want to stay in their home countries for as long as possible, often retuming to the club a day or just a few days before the first training session. This compromises the quality of their training sessions in the first week of preseason, and it could lead to overtraining because of insufficient recovery from "travel fatigue" (Reilly et ai. 1997). Ensure that players report for preseason training fresh and free from jet-lag, because this will allow time for the players to settle in and cope with the demands of preseason training. 296 1 FITNESS IN SOCCER FITNESS IN SOCCER Macrocycle: Preseason Macrocycle: Preseason 16.3 ORGANIZATION OF THE MESOCYCLE In the preseason phase, we opt for a six phase periodization strategy. Because preseason can extend over a period of five, six, seven and sometimes even eight weeks, a phase in this mesocycle may be shorter or longer than a week. These six phases are structured such that they comply with the concept of fatigue management. ln the preseason macrocycle, loading strategies are therefore alternated with recovery strategies within each microcycle. At the end of the mesocycle, a microcycle of unloading (tapering) is planned so the players can start the season "fresh." The preseason mesocycles differ from in-season mesocycles in that there is no specific tapering planned in the various microcycles before preseason matches. This is the structure of the preseason mesocycle: Volume phase • Extensive endurance phase (EEP) 0 Intensive endurance phase (IEP) • Unloading phase (UP) Intensity phase • VO,m., phase (V02P) • Interval phase (IP) • Speed phase (SP) • Tapering phase (TP) 16.3.1 Extensive endurance phase (see table 16.2) Training forrns: • Aerobic endurance • Continuous extensive • Fartlek variable ° Continuous intensive 16.3.2 lntensive endurance phase (see table 16.2) Training forms: 0 Aerobic endurance - Continuous intensive - V0 2max interval - Long-interval loads 16.3.3 V02 max phase (see table 16.3) Training forms: 0 V0 ma~ interval 2 - Long-interval loads - Medium-interval loads 0 Short-interval loads 16.3.4 High-intensity phase (see table 16.3) Training forms: o vo2maxinterval - vo2m.lx repetition - Long repetition loads - Medium repetition loads - Short repetition loads - Repeated sprint exercises 16.3.5 Speed phase (see table 16.4) Training forms: • Resistance - Starting speed • Acceleration 0 Maximum speed • SAQ training 0 Medium repetition 0 Short repetition 16.3.6 Tapering (see table 16.4) Training forms: • Tapering strategies Preseason Macrocycle Macrocycle Mesocycle Microcycle Mesocycle Volume Mesocycle lntensity l endurance lntensive 1Unload' VO,~ l lnterval ing Extensive endurance Table 16. 1: Organization of the preseason macrocyc/e 1 Speed 1 Tapering i 297 298 1 FITNESS IN SOCCER Macrocycle: Preseason 16.4 FRIENDLY MATCH PLANNING IN THE PRESEASON STAGE Casamichana et aL (2012) compared the physical demands of friendly matches (FMs) and small-sided games (SSGs) in semiprofessional soccer players using GPS technology. The researchers found the distance covered in the speed zones greater than 21 km/h was significantly higher in FMs as opposed to SSGs. Moreover, more sprints per hour of play were performed during FMs, with greater mean durations and distances, greater maximum durations and distances, anda greater frequency of sprints of 10-40 and >40 m. Finally, they demonstrated that the frequency of repeated high-intensity efforts was higher during FMs. The results of this study (Casamichana et ai., 2012) suggest that coaches should consider FMs during preseason to elicit specific adaptations in the domain of high-intensity effort. Belo\v are a number of rules for planning and playing preseason fríendly matches: 1. Do not plan matches in the first week. Players often retum after the summer period with reduced fitness. They need time to adapt to the load of soccer training again. If a friendly match is planned, it is best done against weaker opponents, with the players not playing for more than 45 minutes. 2. Plan games according to the number of players. Coaches sometimes make the mistake of planning two matches per week for a squad of 18 players. It should be remembered that improving performance is the main objective. This means that training needs to be approaching the injury threshold, and this leads to players often experiencing minor problems (medical attention injuries). Playing with these medical attention injuries carries a great risk. There will also be players who cannot participate in all of the preseason because of intemational obligations (professional players), jobs (amateur players), or holidays. It is therefore better to plan friendly matches based on one per 16 players, possibly planning games against the reserve team or lesser opponents in the middle of the week. These matches can potentially be delayed to later in the preseason phase, or using the players of the reserve team. 3. Varying playing time. Start by getting everyone to play for 45 minutes. Then progress players up to playing for 60, 75 and finally 90 minutes of match time before the competitive season begins. Ideally, every players should have participated in at least two full games before the competitive season commences. 4. Preseason is for all players. Preseason is an important period for all players. If a player has a poor preseason, this will jeopardize the rest of the season, so develop a preseason program for all players rather than just the first-choice players. 5. Varying intensity. Try to vary intensity during preseason friendly matches. For example, players can be instructed to play a high-pressing game for 15 minutes. This will boost the intensity, which in tum increases the load. This load can then be built up in the following friendly matches. Periods of ball possession can also be played in FITNESS IN SOCCER Macrocycle: Preseason order to reduce the load. This can be clone in one of the first weeks of the season, for instance, if volume is the main objective. Example of buildup: o 45 minutes ball possession • 15 minutes ball possession, 15 minutes pressing, 15 minutes ball possession • 15 minutes pressing, 15 minutes ball possession with low defensive line, 15 minutes pressing • 45 minutes pressing 6. Plan the quality of your opponents. Players will be fatigued during preseason because of the increased load, and this will inevitably compromise performance. When planning opponents for practice matches, it is therefore important to make the right choice. Preseason should start with matches against weaker opponents before facing stronger opponents in the last two weeks (when the load has decreased and performance and preparedness will increase). When selecting the opponents, coaches should consider that everyone in the club will have their own expectations. Suppose you play against a second-class foreign team in week 2. However, this team starts its league the follo\ving week and plays 90 minutes with its strongest team. You are still working on building up fitness, and your team will therefore accumulate fatigue. Therefore, players will be fatigued, or at least Iess prepared, when starting the game. The result might be that you lose the game, resulting in dissatisfaction both intemally and externally (media and supporters). Try to avoid this, because the mental aspect cannot be detached from the physical aspect. For this reason, practice matches should be arranged against lesser local teams before subsequently facing stronger teams. 7. Important competitive matches during preseason. You might possibly have to compete in a European or other cup competition during the preseason phase. Your pre-season plan will have to take this matter into account. Clear choicelmportant, strategic decisions have to be made, and communicated to all of the clubs players and coaching staff. 1 299 300 1 FITNESS IN SOCCER Macrocycle: Preseason FITNESS IN SOCCER Macrocycle: Preseason 1301 16.5 ORGANIZATION OF THE PRESEASON TRAINING CAMP Training camps are often used in an inappropriate way to subject players to excessive loads. The training camp schedule should be organized in such a way to enable players to recover from training sessions in an optimal manner. As a result, the training load can be increased gradually. All the recovery strategies (e.g., sleep, rest, nutrition, hydration, etc.) can be scheduled in an optimal way to ensure that fatigue between sessions is reduced as quickly as possible. Planning a preseason training camp is an important consideration. ln the past, a training camp was often organized to start in the first two weeks of preseason. This often led to injuries because of the load increasing far too quickly. A training camp in preseason is best scheduled at the start of the third or fourth week, ideally before the unloading phase. Double sessions are regularly planned during those weeks. It is also important to consider the objective of a training camp. Is the aim to strengthen team spirit or improve fitness? Or is it a combination of the two? Anight out or team-building activities like go-karting will disrupt and delay recovery. A training camp is not necessary for organizing a group activity, but if it is planned as a team-building activity, it should be accompanied by a reduction in workload. Training camps can also be organized solely for the purpose of playing friendly matches. Professional soccer players may cover a distance of 30-45 kilometers during a normal training week, which is approximately 70% of what a professional player can process each week. Exceeding this threshold will lead to an exponential increase in the number of injuries. Ekstrand and Gillquist (1983) examined the injury incidence of soccer players during training camps. Each soccer team in this study had two training camps, one in March-April before the start of the Spring league play and one in July before the start of the Autumn league play. The Spring season camp, lasting three days with one to two practice sessions each day, had an injury incidence of 21.3 ± 15.2/1000 hours, which is three times that of average practice injury. The Autumn training camp, lasting five days with one to two practice sessions per day, also had an injury incidence that was higher than average, but it was lower than that of the Spring camp (Ekstrand and Gilquist, 1983). Non-impact sessions-such as running in running shoes, cycling, mountain biking, or kayaking-can also be included in a training week in arder to build up fatigue without too much mechanical impact. These are all cross-training options for soccer players during the preseason phase .. There is a lower risk of injury while still keeping a high load level. However, the effects of a new training mode do need to be considered. Cycling involves a very different load to soccer, and it therefore causes a specific form of fatigue. There are examples where coaches organize long mountain-bike rides in the morning as recovery training followed by a friendly match in the afternoon. This is likely to result in muscle injuries. Soccer players are very specifically trained to produce maximum performance. A different mode of training will therefore quickly entail peripheral local fatigue. You could compare this to an elite cyclist having to play a soccer match in the morning and then participate in a cycle race in the afternoon. FACULDADF ne DcSPOltTO DA UNIVERSIDAOE DO PORTO s Macrocycle Preseason ;:: ~ "q -1 z I Mesocycle lntensity om Monday Tuesday Wednesday Thursday Friday Saturday " .,, V> vo2m>x phase Week4 Free Free V> ~~ Sunday ~o AM:V021nt, Lolnt (Vai 80'/ Rpi 12) AM:Melnt, Shlnt (Vo! 90'/ Rpi 12) AM:Mefnt, Shlnt (Vol 80'/ Rpi 12) PM: Strength training 30 x 35"/25" (Core círcuit) PM:V021nt, Lolnt (Vo! 70'/ Rpi 11) PM: Strength training 30 x 35"/25" (Core circuit) AM: Training group 2 Melnt, Shlnt (Vai 80'/Rpi 12) Free Frequency: #7 Volume: 535min lntensity: Rpi: 11.8 Match: 75min ~ n § ;o "n O m PM: Match +++ (75'-15') High intensity phase Week5 AM: Conl (Vol 60' I Rpi 9) PM: V021nt (Vol 60'/Rpi 14) Group 1 AM:V02Rep (Vol 60'/Rpi 15) PM: Strength training 40"/20" (Core circuit) Group 2 AM: V02Rep (Vol 45'/Rpi 14) Group 1 AM: LoRep, MeRep, RSE (Vol 70'/Rpi 14) Group 1 AM: LoRep, MeRep, ShRep (Vol 80'/Rpi 14) PM: Gani (Vai 30'/Rpi 7) PM: Strength training 40"/20" (Core circuit) Group 2 PM: Match +++ (90'-00') Group 2 AM: Conl (Vai 45'/Rpi 10) PM: Strength training 40"/20" (Core circuit) Group 1 AM:MeRep, ShRep (Vol 70'/ Rpi 13) Group 2 AM: Melnt, Shlnt (Vol 70'/ Rpi 13) PM: Strength training 40"/20" (Core circuit) Group 1 PM: Match ++++ (90'-00') Group 2 Group 1 Free Group 1: Frequency: #10 Volume: 580min lntensity: Rpi: 12.2 Match: 90min Group 2 Free Group 2: Frequency: #10 Volume: 580 lntensity: Rpi: 12.2 Match: 90min AM:V02Rep (Vol 90'/Rpi 15) PM: Gani (Vai 60'/Rpi 11) Tab/e 16. 3: Organization of the mesocyc/e intensity in preseason Macrocycle Preseason / Mesocycle lntensity Monday Tuesday Wednesday Thursday Friday Saturday Sunday speed phase Week 6 Group 1 AM: COnl (Vol 60' I Rpi 7) Group 1 AM: Sp, Res, RSA {Vol 60'/ Rpi 16) PM: Strength training 30x 40"120" (Core círcuit) Group 2 Sp, Res, RSA (Vol 70'/Rpi 15) Group 2 AM: Sp, Res, (Vol 45'/Rpi 14) Group 1 AM: Sp, Res, (Vai 80'/Rpi 15) Group 1 AM: Sp (Vai 60'/ Rpi 14) Group 1 :V021nt (Vol 45'/Rpi 15) Group 1 PM: Match Group 1 Free Group 1: Frequency: #8 Volume: 455min lntensity: Rpi: 12.6 Match: 90min +++++ {90'-00') PM: Conl (Vai 30'/Rpi 9) Group 2 PM: Match ++ +(90'-00') PM: Sp, Res (Vol 45'/Rpi 13) Group 2 AM: ConE (Vol 45'/Rpi 9) Group 2 AM: Conl (Vo! 60'/Rpi 19) Group 2 AM: Sp, Res, RSA {Vol 80'/ Rpi 16) Group 2 Free Group 2: Frequency: 8 Volume: 465min lntensity: Rpi: 12.6 Match: 90min AM: Melnt (Vol 45'/Rpi 12) 27 Match (League) Free Frequency: #6 Volume: 335min lntensity: Rpi: 13 Match: 90 PM: Strength training 30x 40"120" (Core circult) Tapering phase Group 1 PM: Conl (Vol 45'/Rpi 9) AM: V02Rep b(Vol 80'/Rpi 16) Free Group 2 PM: Lolnt (Vai 70'/Rpi 14) AM: V021nt (Vai 75'/Rpi 14) "a~ -<~ " z " m .. " " V> V> ~~ ~o " n iõln om Tab/e 16.4: Organization of the mesocycle intensity in preseason " "' w 5l 304 1 FITNESS IN SOCCER Macrocyc/e: Preseason 1305 FITNESS IN SOCCER Macrocycle: Preseason Frequency lntensity \--···----------·-·-·-----:;/--··---------- ·-·--·--·-------·--··· / •e·-···---·----------·-····---------·-···-·--------·---------·--------··-·-·--· Fig. 16.4: Evo/ulion of intensity in preseason EXlens;ve enduronce lnten•"• onduronce ph••• UnloodlnR ph"o V02mo< photo H;gh lnton<ity ph3'e Spocd ph><e T•porin~ phose ph•<• Fig. 16.2: Evolution of frequency in preseason SUMMARY Volume ,. ---- = ,. '" '" '" '" .. E«•""""'"d"''"'" ~.,. ln!OnW.or><ior>•« p>'>< Uni<"~''"°"'"' Fig. 16.3: Evolution ofvo/ume in preseason 'Kllm"°'"'º H:1~f<"•n1>tvJ>hm s,o .. ~º""' T•p«inHh"' The objectives of preseason are to prepare the team technically, tactically and physically for the forthcoming competitive season. Unfortunately, most coaches train players with too much intensity and volume during preseason training, especially during preseason camps. This leads to players accumulating too much fatigue and sustaining injuries, even before the season begins! Coaches should gradually increase the duration and intensity of training throughout the preseason period. It is also important for coaches to prepare their teams tactically during this period and not place all the emphasis on fitness training. Tactical, technical and fitness aspects can be trained simultaneously, as discussed in the previous chapter. Friendly games can be arranged strategically during preseason, so players are exposed gradually to playing 90 minutes of match play, as well as getting used to the playing style and tactics of the team. FITNESS IN SOCCER Macrocyc/e: Preseason FITNESS IN SOCCER Macrocycle: in~season 1 MACROCYCLE: 1N-SEASON Jan Van Winckel, Werner Helsen, Jean-Pierre Meert, Kenny McMil/an, Paul Bradley REFERENCES 17.1 INTRODUCTION In the preceding chapter, we discussed planning strategies during preseason. ln this chapter, we will discuss how the in-season phase can be structured. The match is the most important event of the week during in-season, and everything is therefore focused on attaining optimum performance on that day. Team success can be partly attributable to the planning and execution of appropriate in-season training periodization strategies. As explained in the previous chapter that discusses fatigue management, planning during the in-season period is focused on performance stabilization. It comprises four phases in each microcycle: recovery, loading, tapering, and the match. The load can only be varied in the loading phase of every microcycle. Amigo, N., Cadcfou, j,,\., Ferrcr, !,, Turados, N,, and Cusoo, R., 1993. Effcct of sumrncr intcrmis.sion on skeletal musclc of ado!.,,,ccnt socccr plnyers, /ou mal ofSporl!i Medicine and Phyok.11Fitnc~:;,38(•1), pp.298-30-1. Bangsbo, /., Mohr, M. and Krustrup, P., 2006. Physica! and mctabolic dcmands of lraining and nrnlch-play in thc dite footbaU playcr. Joumal ofSporl!i Sdcnccs, z.t, pp.665-674. Dung .bo, J. •md Mi7.uno M., 1988. Morphologic<1l and rnetabolic allcrations in sa«er playern with dctraining and retraining and thcir rdalion to performance. !n: T. Rcilly, A. LC<.-.,,, )(. Davids, W,j. Murphy, <xfo. 19813. Sdcnre and football. London/New York: E nnd FN Spon. ppJl•J.124 17.2 DURATION OF THE MESOCYCLE 0 Bang~bo,J., 199·b. Physic,1! ronditioning. ln: B. Ekblom, cd. 1994. Football (Sorcer). Oxford: Blackwell Scicnlific. pp.12-1-133. Bang,bo, J.. 199·11.>. The physiology of wcC\!r - With speciol rcfcrcnC\! to intcnsc intcnnitlent cxcrcise. Ac!.t Physiologica &andinilvica, 151: pp.1-155. füng,bo, )., Mohr, M. and Krustrup, P., 2006. Physic,11 ilnd rnctabolic dcmolnds of lrillning and match-ploly in lhe elite foolbolll playcr. J 5portsSci., 24(7), pp.66S-74. Cn~ilrnkh.tn.t, O., C1~tdlnno, J. and Cast.1gna, C., 2012. Cornparing thc physirnl dcmands of fricndly rnatchcs nnd srnilll·r.idcd games in scrniprofc%1onal soccer plnycm. J Strcngth Cond Rcs. 26(3), pp.837-S.J3. Coopcr, K. H., 1968. A mcolns of ar&.'r.~.ing rnn~irnal oxygcn uptake.Joumoll of thc Arnerican Medical Asoociation, 203, pp.201-204. EMtrand ). ond Gillqufatj., 19!13. Titcavoidabfüty of soccer infurics. !ntJ Sporlfi Mcd, ·H2~ pp.12'1-8. Hclgerud J., Wir,]Qff, U., Engen L. 'md Holf, J,, 2001. Acrobic cndurancc lrnining improves so«cr performance. Medicine and ScienC\! ín Sports and Excrdsc, 33(11), pp.1925-1931 )cong. T.S., Rcilly, T., Morton, J., Bac, S.W. and Drust, B,, 2011. Quanlification of thc physiologlcal !oadini; of one weà of µprc-scuson" and onc wcckof ""in-tcasonH troining in profcssiona! socccr plnycrs.Joumnl of sporb 1;dcnc\'S, 29(11), pp.1161-6. lrnpcllizzcri, EM., Ma reoro, S.M., Ca~tíll)!lil, C., Rei!!y, T,, S~s,;i,A. and fain, F.M., 2006. Phrsiological and performance cffcc\!! of gene ri e vcrnus opccifk acrobic tr.1inini; in SOCC\!t playcro. lntcmational /oumal ofSport> Medicine, 27, pp.483-492 Mogarcy, M.E., Estcrrnan, A., Spccchlcy, M., !k,15c, E. and Hcyncne, M., 2013. TI1c rdotiorn;hip bctwecn pn.-sc;i,;on fitnec.>5 lcsting nnd injury in dite junior Au>trnlian foolball playcrs. ]ou mal oi &iencc and Medicine in Sport, 16(·1), pp.307-311. McMilfon, K., Hclgcrud, J., Gmnt, S,, Ncwcll, J., Wilson. J.• Mncdonald, R., and Holf, J., 2005. Lictatc thfl'Shold rcsponsc-s to a ocason of prof.,,;oional British youthsoro."r, Br J Sports Jl.lcd, 39, pp..132~136. Rcilly, T., 2007. Thc trnining pro=s. ln: Thc scicnC\! of trnining - sorC\!r. A sdcntific approach to dcvcloping olrenglh, opccd and cndurancc. London: Routledgc. pp.l-19. Rcilly, T., Morton, J., Sang·Won Bac, Drust, B, Tae-Scok Jconzy 2011. Quanlificntionof thc physiological looding of onc wcck of "pre-sca· son"' and onc wcck of "in-oca~on" training in profcssional r.ocC\!r playcrs. Joumal ofSporWScicnccs, 29(11), pp.1161--6. Rcilly, T., Atkinson. G. and WatcrhouscJ., 1997. Travei fatigue and jct-log. / SporWSd, 15(3), pp.365·9. Rcilly, T., 1997. Encrgctks ofhigh-intcnsity excn:~ l<OCC<!r) with parti cu for rderenC\! to fotiguc. J Sporls Sci, 15, pp.257-2&3. Stonc N.M. and Kilding A.E., 2009. Acrobk Conditionini; for Te~rn Sporl Athle1~'S. Sporl~ Med, 39(8), pp.615-6-12 17.2.1 Terminology When a periodization phase of three to six weeks is mentioned in the literature, this refers to the mesocycle. For the in-season phase however, we opt for a three-phase mesocycle. It is difficult to prove the efficiency of a three-, four-, five-, or six-phase mesocycle in soccer. There are so many factors influencing a match that it is almost impossible to design research that empirically and quantitatively proves a three-phase cycle to be more advantageous than its six-phase counterpart. The issue of periodization during the in-season period is based on best practice rather than evidence-based findings. Although we have tried to present relevant research findings where possible, most of the concepts discussed in this chapter are intuitive or anecdotal. However, it would be helpful for researchers to report findings that could add to the evidence base and therefore fully support or reject these anecdotal reports. Before looking at the structure of the mesocycle in detail, we first set out a number of principies to explain why we opt for a three-phase cycle during in-season. 1307 308 1 FITNESS IN SOCCER Macrocycle: in-season FITNESS IN SOCCER Macrocyc/e: in-season 17.2.2 Metabolic training versus neural adaptation One criteria for defining the duration of the mesocycle could be based on whether the aim of training is metabolic or neural in nature (Nádori et al., 1989). Longer cycles are suggested for metabolic training and rebuilding fitness during preseason, and shorter cycles are suggested for neural adaptation in arder to stabilize performance during in-season. 17.2.3 Accumulated fatigue Zatsiorsky (1995) eluded that long periods of high-intensity training quickly resulted in fatigue. The body needs a period of relative rest (unloading) after a few weeks of training (loading). This gives the player time to recover and convert the work produced into functional adaptations (supercompensation). For this reason, after a two-week training period, we typically schedule a week of active rest (unloading) where the intensity is kept high while volume and frequency are reduced. 17.2.4 Detraining One of the shortcomings of multi-phase mesocycles is that it takes a while before a specific physical ability (PA) is trained (e.g., speed, aerobic endurance, power). lf a PA is not trained for a period of six to ten days, detraining occurs (Arciero et al., 1998), and this causes the performance levei of that PA to compromise the player's overall physical performance. ln addition, that specific PA will decrease to such an extent that retraining it will take longer than it took to Iose it. 17.3 ORGANIZATION OF THE MESOCYCLE The three-phase mesocycle is repeated in the competition macrocycle (in-season). 17.3.1 Physical abilities: Parallel or concurrent training We explained the various possibilities for organizing a training plan in the chapter about periodization. ln this book, we opt for a parallel/ concurrent approach, where all PAs are trained simultaneously. 17.3.2 Physical parameters: Linear (volume) and undulating (intensity) Volume decreases linearly in each mesocycle, while intensity increases at first and then decreases in the unloading week. 17.3.3 Workload: Reverse step loading Finally, we prefer "reverse step loading." The load is decreased each week dueto a decrease in volume. The intensity is retained as much as possible in order to counteract the detraining effect. -<$- lnten~ity ~:z-volume 17.2.5 Concurrent training Severa} team sports require different PAs, such as endurance, power, speed and strength. For example, in a soccer game, a player may be required to sprint past his or her opponent to score a goal (explosive power), deliver a hard body check (strength and muscularity), and run 11 km in a single game (endurance). The inclusion of resistance training (to gain strength, hypertrophy, and power) combined with aerobic exercise (to enhance endurance) in a single program is known as concurrent training (Wilson et al., 2012). The biggest issue that can arise from this sort of programming is that the two or three PAs that coaches are looking to enhance often end up competing with each other for adaptation. ln soccer, however, unlike some other sports (e.g., 100m sprint, cycling, marathon running, etc.), it is unnecessary to reach the maximum genetic potential for every PA required. Soccer players must develop all the required PAs, but with specific individual adjushnents according to a player's technical ability and position. 17.2.6 Adaptability A three-phase mesocycle is easier to adapt and therefore more flexible than a sixweek cycle. This gives the coach the possibility of adjusting his or her planning more easily. --.k-Tralnlng load Volume phase lntensity phase Unloading phase Fig. 17.1: Three-phase mesocycle 17.3.4 Neutral week ln weeks (microcycles) with midweek competitive matches, it is important to incorpora te a neutral week and defer the mesocycle by one week. 1 3 9 o 310 1 FITNESS IN SOCCER FITNESS IN SOCCER Macrocycle: in-season 1311 Macrocycle: in-season 17.4 THREE PHASES OF THE "IN-SEASON" MESOCYCLE 17.4.1 Volume phase o Objective: The objective of the volume phase is to improve aerobic fitness, and especially the central component. At intensities close to the lactate threshold (-70-80% vo2m~x' physiological adaptations occur primarily in the peripheral component. Significant peripheral adaptation occurs, with substantial changes in muscle capillarization, oxidative enzyme activity, mitochondrial volume and density, myoglobin, and the preferential use of free fatty acids as an energy substrate. It is therefore important to use exercises where the players are constantly moving (e.g., passing drills or tactical exercises where the players are forced to cover long distances). Other exercises include possession games where the players are given certain tasks, meaning there are few orno breaks. • Periodization: The emphasis is placed on volume during this week. The PAs of speed and strength are maintained. Strength endurance is trained as well while trying to avoid interference with endurance. 0 Physical ability: Aerobic capacity • Methods (See chapter 5): Continuous extensive, continuous intensive, • Training para1neters: - volume: 100% - intensity: 70% - frequency: 100% • Strengtl1: Strength endurance 17.4.2 lntensity phase 0 Objective: The objective of the intensity week is to improve aerobic power, repeated sprint ability, and SAQ (speed, agility, quickness). This is done using High-intensity intermittent training (HIIT). These adaptations include an improvement in the heart's capacity to pump blood, primarily through increased stroke volume, which occurs because of an increase in end-diastolic volume and an increase in left ventricular mass. Subsequently, these adaptations result in an increased cardiac output, which, according to the Fick equation, will increase V0 2max (Stone and Kilding, 2009). • Periodization: The emphasis is on intensity during this week. The PAs of aerobic fitness, repeated sprint ability, speed, agility, quickness, and acceleration are trained. 0 PAs: Speed, agility, quickness, aerobic power • Metlwds: (See chapter 6) Interval, repetition, SAQ RSA 0 17.4.3 Unloading phase 0 Objective: The objective of the unloading phase is physical, neural and mental recovery. This is mainly achieved by reducing the frequency and volume of training. During this week, players are given the opportunity to recover from the load they have experienced over the previous two weeks. Intensity is kept fairly high to ensure that any loss of fitness (detraining) is minimized. It is through reductions in the other training parameters (volume, frequency and duration) that recovery should be realized. 0 Periodization: All of the physical abilities are maintained during this week. There is no aim to improve any particular PA. • PAs: Maintenance with the emphasis on soccer-specific exercises and mental and physical recovery 0 Methods: Continuous and HIIT methods at max 90%. • Training para1neters: - volume: 50% - intensity: 80% - frequency: 65% 17.5 REMARKS 17.5.1 Length oflhe different phases The length of a microcycle can vary in every mesocycle. ln soccer, a microcycle is often equated to seven days, but this is not always necessary. A three-phase mesocycle can last two or five weeks, depending on the number and timing of matches. As we have already explained before, a periodized plan should be adapted according to the match schedule. 17.5.2 Periodization of speed Within this periodization model, each ability related to speed, agility and quickness (SAQ) (e.g., repeated sprint ability, speed, agility, etc.) should be trained every week to avoid detraining. Match Recovery Recovery G +1 +2 -4 -3 No No Speed endurance Repeated sprint ability Training para111eters: - volume: 70$-'b - intensity: 90% Loading Loading Tapering Tapering Match -2 -1 G SAQ Short maximal sprints with sufficient (1/10) recovery - frequency: 85% • Strength: Speed strength and maximum strength Tab/e 17. 1: Periodization of speed 312 1 FITNESS IN SOCCER Macrocyc/e: in-season FITNESS IN SOCCER Macrocycle: in-season 1313 Player(s) 1 60" 90" 1,2,3,4 5 - 5 30" 6,1 6, 1 60" 1,2,3 - 4,5,6,1 - 4,5,6,1 2 2 3,4 - 3,4 60" 5,6,1 - 5,6,1 90" 2,3,4,5 - 2,3,4,5 6 - 6 30" 1,2 1,2 60" 3,4,5 - 3,4,5 00 6,1,2,3 6,1,2,3 e 4 - N 5,6 - 5,6 60" 1,2,3 - 1,2,3 90" 4,5,6,1 - 4,5,6,1 120" 3 - 3 30" 4,5 4,5 60" 6,1,2 - 6,1,2 90" 3,4,5,6 - 3,4,5,6 .. t- <D .. .. .. .. •o 'E N N t- t- ~ "'e ';; .. N <D ~ ~ 2o v "-B .E M "ueo • V A M ::> B 00 00 o M .. • •o. 00 ~ 1" ·;;; e 2 B v "-B ~ .Ee M M V A B M 00 "'"' "O Q) "O ~ ro • 00 •o. ~ o E o :l! E ~ V A ~ B 00 "' '° ,.; ~ > o u ~ 2:' 2:' "'>uo >"'uo 2:' E ~o o 2:' 2:' w "'ou> "'u>o i" i" i" N N N > o u "e "e "e "e "e "e "e "' "' "' "' "' "'"' "' ~"' 2"' 2 2"' 2"' 2 2"' 00 ~ ~ e e E .E .,. ... .,. o 2:' w o u > i" e z ~ N ~ o ~ i" M .1i N N e ~ t- "" "'"" "'"' "' "" "' "'"'"' I' .••• <D i" V A .. ~ .Ee ~ .Ee ~ .Ee ~ .Ee ... ... ... ... ...w "'w w <D t"'w "' E "' E E E E "' E (!) "' (!)"' (!)"' (!)"' (!)"' (!)"' (!)"' ~ E N 1,2,3,4 1,2,3 4 120" 90" 120" 30" 120" 90" 120" 30" 120" ' ' N " "'B " .. t- i" o ::> ' t- N N e .. N .E ~ cn .. 2o cn Q) .. N 2:' w Q) .. .,. "' .,. "'<D <D "" "'"" .,.""t"'"" "" "" "'"" "' ~ cn E 30" 4.5.6 "' ..."' ... "' "' "' "' "" "" "" "'"" "" """' "" ' ' ' ' ' ... "' .,. "' "'"" "'"" "" "" "'"" "" "" o. Duration 2,3 .. ~ - Result - 2,3 4.5.6 • •• Players(s) 1 Table 17.3: Example of a competition formal (intensity phase). There are two teams of six players. Each player is given a number. Games of 1><1 to 4><4. The pfayers with the number 1 play against each other for 30 seconds, and players 2 and 3 then p/ay 2><2 against pfayers 2 and 3 from lhe other team for 60 seconds, and so on. Tips for organizing small-sided games (SSGs) 0 Agree on a reward or punishment for the winning or losing team before the practice. This "\vill provide extra motivation for the players. ° Keep track of the individual scores throughout the season. 0 Organize the teams so the competitive environment remains as wide as possible. ln the 4v4 games, for example, teams of two players can be made to play with another pair against two new pairs each time. This increases the intensity of the games. 0 Make sure enough balls are available. 0 Organize pitch sizes with different dimensions and rules. This enables the players to work in different training zones and makes it easier to set up different training plans for individual players. 314 1 FITNESS IN SOCCER Macrocyc/e: in-season 17.5.4 Pre-training routines Pre-training routines comprise: o Pre-activation exercises o Injury prevention o Core stability o Core endurance (dynamic} o Core strength (dynamic) o Dynamic mobility o Functional strength o Dynamic stretching o Neuromuscular control Pre-training routines can be performed before the start of each training session and have the additional benefit that the players are better prepared for the next training session. These sessions last between 20 and 30 minutes and are best dane indoors. 17 .5.5 Flexibility training Flexibility training is an element of injury prevention. Static stretching is best organized at the end of a training session. The temperatures of the muscles are still high, so this is an ideal time to increase flexibility. Passive or active stretching should not be used before the start of a training session (see the Chapter 19). 17.5.6 Freshness sprints The duration of the training session should be reduced by around 50% on the day before a match. Training should last at the most 45-60 minutes in arder to provide the players with the freshness they need for the match. However, the intensity should be kept sufficiently high (80%). This is done by playing small-sided games for a maximum of two minutes with sufficient recovery and short maximal sprints. 17.5.7 Home programs Soccer players are individual athletes who play together in a team on match day. Every player is different, and each player needs a different load to make progress. Training in soccer is too often adapted to the average player, meaning that physically weaker players are overloaded, while the physically stronger players are subjected to an insufficient load (Hoff et al., 2002). Hence, there has to be a good balance between tactical sessions, where the players train in a group, and individual sessions to improve players. One of the tools a soccer coach can use to individualize training is the use of home programs. These home programs have many advantages. Players do not lose any time, so they have more time to recover and can adjust their training to their family / work/school situation. ln addition.. training can be easily adjusted to a player's individual needs. These training sessions can also be checked using HR monitors or GPS <levices. Thus, home programs are ideal for non-professional players, but they can also be used for professional players, especially during recovery sessions. FITNESS IN SOCCER 1 Macrocycle: in-season 17.5.8 Use of shooting exercises Shooting exercises are popular among soccer players. Although such drills are fun to do, they can produce a local overload within the muscles that are involved. Additionally, these shooting exercises are often not used specifically in the context of the game. For example, allowing central defenders, who rarely go forward during a match, to shoot continuously at the goal is not only pointless; it also increases the local load of the muscles. These shooting exercises often result in exercise-induced muscle damage (EIMD), and this can lead to strain-type muscle injuries. A few guidelines: • No shooting exercises less than 48 hours after a match (recovery phase) or less than 48 hours (tapering phase) before a match. • Integrate shooting only if players are not fatigued and are htlly warmed up. 17.6 INDIVIDUAL PERIODIZATION Individual periodization involves the individual planning and adjustment of load for each player. For example, older players may get an extra day off or be allowed to skip the afternoon session. Altematively, players may be given a different role (neutral player or joker) during a game or possession drill. Improving players and allowing them to reach their maximum genetic potential requires structured planning. 17.6.1 Age The rate at which physiological adaptation occurs is variable (Vollaard et al., 2009) and seems to depend on the volume, intensity and frequency of training. Importantly, the development of physiological capacities seen in elite athletes does not occur quickly, and it may take many years of high training loads before peak leveis are reached (Laursen.. 2010). Young soccer players often struggle to cope with the increased training load. Rapid increases in training frequency, and thus training load (sometimes up to 100%), during the transition from youth to elite football can be difficult for young players to process. The body's ability to recover after training and matches also changes with age. With increased age, the muscles' ability to repair and adapt is diminished. This could be caused by a decrease in muscle capillarization and mitochondrial activity (Du et al., 2005; Fell and Williams, 2008). Older players may recover more slowly from training and matches, so they may need more time between successive sessions. 17.6.2 Weight/BMI Players with a higher body weight experience a higher mechanical load on their joints. When changing direction, the load can be five times the body weight (or even up to ten times body weight for a vertical jump [Ortega et al., 2010]). This mechanical load is consequently higher for heavier players than it is for lighter ones. One match involves approximately 1,300 changes in activity (Chaouachi et al., 2012). The mechanical impact on players is therefore higher compared to players who are not so heavy in relation to their height. ln this regard, Boume et al. (2005) reported a decrease of cartilage cell viability \vhen applying impact loading to an animal k.nee at higher energy and increasing loading repetitions. However it should be highlighted that only limited conclusions can be derived from these 315 316 1 FITNESS IN SOCCER Macrocyc/e: in-season reports in regards to the human articular cartilage properties in vivo.(Brüggem~nn, 2011). As díscussed in previous chapters, data from accelerometers in GPS <levices may be used to quantify the body load placed ?~ p~ayers to allow monitoring to take place, especially for players more prone to 1n1unes. 17.6.3 Players returning from injury A player who has sustained a harnstring injury, for example~ can skip a trai1?ng· session to allow him to work on the functional strength of hts or her hamstnngs and other muscle groups to improve functionality and reduce the reoccurrence of FITNESS IN SOCCER 1 Macrocycle: in-season 17.6.7 Playerrole Midfield players, full backs and wingers often experience a higher load during training sessions compared to central defenders or strikers. Wingers and full backs often have a higher physiological load because of the regular use of cresses in tactical exercises. ln these exercises, wingers and full backs have to cover more distance than other positions in the team. Midfield players on the other hand often experience a higher mechanical load due to the demands of their position. They cover shorter distances but make more changes in direction. injuries. 17.6.4 Fast and slow players Fast players can often have a higher proportion of fast-n:itch .fibers, while slower players frequently have a larger proportion of .sl?w-~itch. fiber.s. Both types of players will therefore respond differently to trammg stimuh. Qu~ck players (e.g., strikers, wide players) with less aerobic potential do not endure high loads as well as players who are notas fast (e.g., central players in midfield and defense). 17.6.5 Players with a history of injury A previous injury is an important risk factor for soccer inju1y. (Hãgglund et al., 2006). Before the start of the season, it is important to get an ide~ of ea~ player's injury history. In soccer, questionnaires have been used at vanous s~ll le~els to obtain information about the sports and medical histories of players, 1nclud1ng previous injuries (Steffen et al., 2008). Training content can then be adapted based on the injury history. Two examples: . . . • A player who has suffered a cartilage injury: The number of tmpact tra1n1ng (mechanical load) sessions needs to be reduced for this player. • A player \Vith a history of muscle injury (e.g., hamstrings): This player needs to follow a special program to restore muscle strength and balance. 17.6.6 Players with minor physical problems The literature describes two types of injuries. A player able to train but with reduced intensity or volume is classified as an "injured player." These injuri~s are referred to as "time loss injuries" (TL). ln addition to this, Fuller et al. (2006) introduced the concept of medical attention injuries (MA). These injuries spe.c~fically re.fe: to medically diagnosable complaints without a time loss from competition or tra1n1ng. In this respect, it is different from, and complementary to, the time loss ~':finitio~, because it will not be recorded as an injury while the player fully partic1pates 1n team training and competition. A quarter of these injuries eventua.ll~ l~ad to a time Joss injury. ln an unpublished study of Helsen et al. (2010), MA 1n1ur1es as apredictor of subsequent injury was investigated. The researchers concluded that ~~re than a quarter (26%) of MA injuries resulted in a TL ínjury withi.n a ye~r. iY!A1niuries should be considered a valuable predictor of reinjury. The1r morutonng and follow-up are key factors within a multidisciplinary injury-prevention approach. A specially adapted training schedule can be incorporated into the weekly planto eliminate a possible maladaptation. 17.7 HOW TO IMPLEMENT INDIVIDUAL PERIODIZATION There are many ways to implement individual periodization, so it is therefore necessary to differentiate as much as possible. Exercises must be specific and therefore directed toward the requirements of a specific position. This means that the technical, tactical and individual physical periodization of this player should be adjusted according to the player's role and characteristics. A professional team with a high number of coaches should therefore ensure they work with the players as individually and specifically as possible. This approach has proved to be successful in some studies. Andrzejewski et al. (2010), for example, demonstrated a significant impact of the individualization of training loads on the development of speed abilities in the examined players. 17.7.1 Adjustments in frequency Players can skip training sessions or take part in additional training sessions. 17.7.2 Adjustments in volume/duration Coaches can individualize training load by varying the duration of training for individual players. A good example of this is the real-time monitoring of small-sided games. Adjustments in load can be made directly after the small-sided games. 17.7.3 Adjustments during training sessions Group training sessions can, and should, be specific. Consider a winger who constantly has to run along the flank during a tactical exercise in arder to deliver a cross. Although the task of this player is specific, coaches do not ahvays consider the additional training load for that player. Another example is a player taking dozens of comer kicks, leading to increased local fatigue of the leg muscles. 17.7.4 Adjustments during small-sided games A coach can schedule small-sided game tournaments in order to assign more or less load to individual players. Certain players can take part in a greater or fewer short games. For example, one player may need to play a series of only eight 4-minute 4 vs. 4 games, while another player performs twelve. You can also choose to vary the pitch dimensions to change the dynamic of the game. For instance certain players could always play on a bigger pitch rather than take part in SSGs to reduce the amount of mechanically intensive accelerations and decelerations performed. 317 318 1 FITNESS IN SOCCER FITNESS IN SOCCER Macrocycle: in-season 1319 Macrocycle: in-season SUMMARY Planning during the in-season period is mainly focused on performance stabilization. The weekly program usually comprises four phases in each microcycle: recovery from the last match, loading, tapering, and the match. The aims of the training week are to maintain the players' fitness (or indeed improve fitness where possible) while performing technical and tactical drills and ensuring that the players go into the next match as fresh and as free from fatigue as possible, as well as being technically and tactically prepared. Each player's training program should be individualized as much as possible. Technical, tactical and fitness work periodization of this player should be adjusted according to the player's role, characteristics, and fitness/fatigue leveis. Physical ability Aerobic endurance Methodical Trainlng Continuous principie (without recoveries) Abbreviation Volume (min) Repitltions lntensity (Hfmax) % Long s!ow distance LSO 60-100 1 60 Continuous extensive ConE 15 - 30 1-4 70 Variab!e endurance method CV 30-45 1-3 60-100 Fart!ek variable method Fa 30- 45 1-3 60-100 Continuous intensive Conl 8-15 3-5 75 Training Methods lnterval method (Medium to intensity, medium to high volumes) Anaerobic endurance lnterval principie (incomplete recoveries) vo2m:;x interval VO)nt 5-8 6-12 85-90 Long interval toads Unt 3-5 5-6 90-95 Medium interval loads Mint 1-3 8-15 90-95 Short interval loads Sint 30-60sec 10-20 90-95 Repetition method (High intensity, limited to low to medium volumes) vo2m:lx repetition V0 2Rep Long repetition load LRep Medium repetition MRep 4 6-12 90-100 2-3 3-5 95-100 1-2 6-12 95-100 Short repetition loads Srep 15-60sec Btot 10 95-100 3-8 - Repeated sprint Repetition principie (incomp!ete recoveries) Repeated sprint exereises RSE 3-7s Resistance lnterval principie (against resistance) Seis of explosive sport-specific movements Res Various depending on exercises 5-15 Speed Repetition principie (complete recoveries) Maximal contrac!ion speed method 3-75 10-20 Sp •§ z Table 17.4: Overv1ew of lhe physicaf ab11ities and their abbreviations used ín the following microcycfes - •§ z w e o ü w ~ ;;: Volume phase semi-professional level Match day {e.g. Sunday) +1 {Monday) Fatigue managment Recovery strategies Frequency (#) Volume (min) +2 (Tuesday) 4 (Wednesday) -3 Thursday) -1 (Saturday) -2 (Friday) Recovery strategies Loading strategies Loading strategies o~ V> '" 1 sessions: 4 70o/o 75'% SAQ Nane Repeated sprint abi!ity Coordination and agility Freshness sprints Strenglh endurance: Strength/Core/ Stretch Nane Strength endurance I Core circuit Dumbbell and barbell upperbody Preactivation Training methods ConE Vo21nt, Lolnt, Melnt, Conl, V02 lnt, Lolnt Lolnt, Melnt Small sided games 7v7 to Possession games /passing and shooting dri!ls I tactical drills Cross-country running / cyc!ing I aquajogging f deep water running 4v4 n ~ !il '" o~ "' # Minutes: 285 50 >75o/o Free ~ # training 90 100 45 9· nô 1 1 1 z ~ Tapering strategies Tapering strategies 50'% Individual periodization Total "!:l.' V> lntensity (%) Training forms ~ " --< qz min Average intensity: 67"/o Match (Sunday) # training sessions: 3 Short small sided games (max. 2') Less or more sma11 sided games Free f Home work Table 17.6: Volume microcyc/e during in-season (semi-professional levei) Volume phase amateur level Match day (e.g. Sunday) +1 (Monday) +2 (Tuesday) 4 (Wednesday) -3 Thursday) -2 (Friday) -1 (Saturday) Fatigue managment Recovery strategies Recovery strategies Loading strategies Loading strategies Tapering strategies Tapering slrategies Frequency {#) 1 1 Total # training 1 1 sessions: 3 Volume (min) 45 90 70 20 60 # Minutes: 220 min lntensity (%) 50'}ó >75°/o 65o/o 85 60"/o Average intensity: 67"/o SAQ Nane Repeated sprinl ability Coordination and agitity Strength endurance: Strength/Core/ Stretch None Core circuit Freshness sprints Match (Sunday) #training sessions: 1 Free Training methods ConE Training forms Cross-country running I cyc!ing I aquajogging I deep water running Vo2lnt, Lolnt, Melnt, Small sided games 7v7 lo 4v4 Conl, V02 lnt, Lolnt Lolnt Lolnt, Me!nt Possession games /passing and shooting drills f tactical drills Cross-country running (5 x 2' ai 85% with 2' rec.) Short small sided games (max. 2') ;;:~ ~ =i o z n rn "!:l. ' V> V> ..ra -z Individual periodization Free I Home work Free I Differentiation in intensity and volume Gray: Possible home program Tabfe 17. 7: Volume microcyc/e during in-season (amateur levei) s· VI ~o ~ !il n n o~ "' '" w ....N w i::l ";::q ~z_, lntensity phase elite level Match day (e.g. Saturday) +1 +2 -4 PM {Tuesday) -3AM (Wednesday) -3 PM (Wednesday) -1 (Monday) -4AM (Tuesday) -2 (Sunday) (Thursday) (Friday) Recovery strategies Recovery strategies Loading strategies Loading strategies Loading strategies Loading strategies Tapering strategies Tapering strategies Total cm ~ V> "' V> Q- !l? z Fatigue management ~·o () ~ ara n "' rn Frequency (#) 1 Volume (min) 45 2 2 65 55 55 20 1 1 # training sessions: 7 55 40 #Minutes: Average intensity: 74% 335 lntensity (o/o) 50°/o 75% >90% 75% 90'% 60°/o 80% SAQ None Long sprint (80%) Repeated sprint ability Coordination and agi!ity Nane Speed Freshness sprints Dumbbell and barbei! upperbody None Core stability and flexibility Preactivation Strength endurance: Nane Strength/Core/ Stretch Core circuit Free ConE Conl Vo2Rep, LoRep, MeRep, V02int Conl, V02 lnt, Lolnt ConE, Conl, Fa, V021nt Conl, V021nt, Lolnt MeRep, Melnt Training forms Cross-country running I cyc!ing I aquajogging I deep water running Possession games I passing and shooting drills / tactical dri!ls Small sided games 3v3 to 1v1 Possession games I passing and shooting drills / tactical dri!ls Non-impact training I physio!ogical load Tactical dri!ls / Sei pieces Short small sided games (max. 90H) Individual periodization Free I Home work Trainlng methods Free f Less or more sma!I sided games Q"' Match (Saturday) # training sessions: 4 Free I Differentiation ln intensity and volume Table 17.8: lntensity microcycle during in-season (elite leve/) lntensity phase semi-professional level Match day (e.g. Sunday) +1 (Monday) +2 (Tuesday) -4 {Wednesday) -3 Thursday) -2 {Friday) -1 (Saturday) Fatigue managment Recovery strategies Recovery strategies Loading strategies Loading strategies Tapering strategies Tapering strategies Frequency {#) 1 1 1 1 Volume (min) 45 70 60 40 lntensity {%) 50 >90°/o 75% 80% SAQ None Repeated sprint ability Coordination and agility Freshness sprints Strength endurance: Strength/Core/ Stretch Nane Core circuit Dumbbell and barbell upperbody Preactivation Training methods ConE Vo2Rep, LoRep, MeRep, V02int Conl, V02 ln!, Lolnt MeRep, Melnt Trainíng forms Cross-country running I cycling I aquajogging I deep water running Individual periodization Free I Home work Free Small sided games 3v3 to 1v1 Less or more small sided games Tabfe 17.9: lntensity microcyc/e during in~season (semi-professional levei) Possession games /passing and shooting drills I tactical drills Short small sided games (max. 90") Totaal #training sessions: 4 # Minutes: 215 min Average intensity: 74% Match (Sunday) # training sessions: 3 q~~ _, Q z nm "' V> "-V> ..ra -z :;· Vl .:, o a"' n "' "' () Qm w N w "'~ lntensity phase amateur levei ;;: :':' " -l ~ Match day {e.g. Sunday) +1 (Monday) +2 {Tuesday) -4 (Wednesday) -3 Thursday) -2 (Friday) Recovery strategies Recovery strategies Loading strategies Loading strategies Tapering strategies Fatigue managment -1 (Saturday) Tapering strategies Totaal ~ "~ 5' ô ~n # training 1 1 Volume (min) 45 80 30 (8 X3')) 60 20 lntensity (0/o) 30% >90~\i 90°,~ 80%1 85% SAQ None Repeated sprint ability Coordination and agility Freshness sprints Strenglh endurance: Strength/Core/ Stretch None Core circuit Training methods ConE Vo2Rep, LoRep, MeRep, V02int Conl, V021nt Conl, V02 lnt, Lolnt MeRep, Melnt Training forms Cross-country running I cycling I aquajogging I deep water running Smal! sided games 3v3 to 1v1 Cross-country running (8 x 3' at 90% with 2' rec.) Possession games /passing and shooting drills / tactical drills Cross-country running (7 x 1' at 90%1 with 2' rec.) Individual periodization Free/Home work Free I Differentiation in intensity and volume V> V> - ~z 1 Frequency (#) z o m sessions: 2 # Minutes: 140 "nm ~ o~ "' min Average intensity: 85o/o Match (Sunday) # training sessions: 1 Free Gray: Possib!e home program T.abla 17. 10: Jntensity microcyc!a during in-season (amateur levei) Unloading phase elite level Match day (e.g. Saturday) +1 (Sunday) +2 (Monday) -4 AM (Tuesday) -3 PM (Wednesday) -2 (Thursday) -1 (Friday) Fatigue management Recovery strategies Recovery strategies Loading strategies Tapering strategies Tapering strategies Tapering strategies Total Frequency (#) 1 1 1 1 1 # training sessions: 5 Volume {min) 45 70 70 55 40 # Minutes: 280 lntensity (%1) 50% >80% 70% 70% 75°/o Average intensity: 69% SAQ Nane Repeated sprint ability Coordination and agility Speed Freshness sprints Strength endurance: Strength/Core/ Stretch None Dumbbell and barbell upperbody Training methods ConE Vo21nt, Lolnt, Mefnt, Training forms Cross-country running I cycling I aquajogging I deep water running Small sided games 3v3 to 1v1 Free I Home work Free I Less or more small sided games Individua! periodization Free Match {Saturday) Core stability and flexibility Preactivation Conl, ConE Lolnt, Melnt Possession games /passing and shooting drills I tactical drills Tactical drills I Sei pieces Small sided games {max. 90") #training sessions: 3 ~~ an -lzm n "<: V> Q. V> 5· Ln ".. -z ~o Si" nn o m Tab/e 17.11: Unloading microcycle during in-season (elite levei) ~ "' "'"' "' ""'~ ;: :!:' Unloading Unloading phase semi·professional level Match day (e.g. Sunday) " -l O m n V> 'l z +1 (Monday) +2 (Tuesday) -4 (Wednesday} -3 Thursday) -2 (Friday} -1 (Saturday) Recovery strategies Recovery strategies Loading strategies Loading strategies Tapering strategies Tapering strategies Fatigue managment Totaal z ~· i:S ~ ~n Frequency {#) 1 1 1 1 # training sessions: 4 Volume {min) 45 70 50 40 # Minutes: 205 lntensity (o/o) 50 >80°/o 70°/o 75'% Average intensity: 69% SAQ Nane Repeated sprint abi!ity Coordination and agility Freshness sprints Strength endurance: Strength/Core/ Stretch Nane Training methads ConE Vo2lnt, Lo!nt, Melnt, Gani, Training forms Cross-country running I cycling I aquajogging I deep water running Small sided games 3v3 to 1v1 Passessian games /passing and shoating drills I tactica! drills Individual periodization Free I Home work Less ar more small sided games Free Q- "' V> "" "' Match (Sunday) # training Preactivatian Core circuit ara nm sessions: 2 Lalnt, Melnt Small sided games (max. 90") Tab/e 17.12: Unloading microcyc/e during in-season (semi-professionaf fevef) Unloading phase amateur levei Match day (e.g. Sunday) +1 {Monday) +2 (Tuesday) -4 (Wednesday) -3 Thursday) -2 (Friday) -1 (Saturday) Fatigue managment Recovery strategies Recovery strategies Laading strategies Laading strategies Tapering strategies Tapering strategies Frequency (#) 1 Tataa! # training 1 sessians: 2 Volume (min) 45 70 20 60 20 # Minutes: 130 lntensity (%) 50 >80% 90'% 60% 85 Average intensity: 70º/o SAQ Nane Repeated sprint abillty Caardinatian and agility Freshness sprints Match (Sunday) Strength endurance: Strength/Core/ Stretch Nane Training methods CanE Va21nt, Lalnt, Melnt, Melnt, Shlnt Conl, Latnt, Melnt Training forms Crass-country running / cycling I aquajogging I deep water running Small side games 7v7 - 4v4 Cross-cauntry running (7 x 90" at 90% with 90" rec.) Passession games /passing and shaating drills I tactical drills Cross-cauntry running {7 x 60" ai 90%, with 2 min.) Free I Hame work Less ar more small sided games Individual periodizatian min Free # training Core circuit sessians: 1 Gray: Possible home program Tabfe 17.13: Unfoading microcycfe during in-season (amateur levei) ~~-l n an zm "' V> QV> ra º" z 5· tn ~o ra n "~ nm § "' w ~ ~ 00 ;;: e; ..,Q z--< Volume phase lntensity phase Unloading phase 7 7 5 Volume 440 380 280 lntensity 67°/o 71% 69% 29480 26980 19320 Frequency Load .____ ' .1 Volume .., soo ~ --- ---- 300 200 ::. (./1 '1 o "'n "~ n m o ,, ~ '"°o Unloadinc lntensity m V> .., i>z " ' V> - 400 Volume Untoading lntensíty lntensity Load 72.% 35000 zº:s;;;: 71% =1 68% a Volume Frequency Elite level 7 67% zz = ::: 3oo<Xl 15000 10000 65% 5000 o 65~' Volume lntemlty Unlooding Volume lntemity Unloadinc Fig. 17.2: Distribution offrequency, volume, intensity and load (elite leve/) ín a mesocyc/e. Frequency Semi-professlonal levei Volume phase !ntensity phase Unloading phase 4 4 4 Volume 285 235 205 lntensity 67% 69~'o 69% 19095 16215 14145 Frequency Lo a d Volume ~I ~-· o +------~----------Volume 1ntensity UnloadTnc Volume 68% 67% Unlooding Lo ad lntensity ::f==:z lntensity . 25000 Z' ' ~------ 20000 15000 ~---------------- ~::::::::":'."'::::::~;;;:;;::::::::::::::::::~::::= + . -1------------------+----------------o+---------------- '0000 sooo 66% Volume lntensity Unloading Volume lntenslty Unloading ~ :!: .., --< az .., m " ' V> Q. .." -z 5· .. o (./1 Fig. 17.3: Distributíon offrequency, volume, intensity and /oad (semi-professionaf levei) in a mesocyc/e. " n "n "'m g ,, "' "" N FITNESS IN SOCCER Macrocycle: in-season FITNESS IN SOCCER Macrocycle: in-season "' ~ -o Q) % .9"' E " õ _I 1 1 > li 1 1 l' ~ ! M ~ 1 i ! 2 ~ o o ~ ~ § "~ ~ § " 1 ~ ~ o " ~ , .,." ~ Q) Q) ~ ... ~ li 1 -~ ~ ~ .E 1 Q) H 4 > -;;; e ~ > u e 1 11 "'~ '4 ! :& -E \ ~ ' § •"E ro \ ! 10' ~ 2o ! ~ -~ ~ _,, Il ! 'ií 'o ~ 1 ! E ~ .; m :'.} N .; rl ~- o ~ ~ ~ ~ § l "~ "e ro O> e 'õ •" ro ro o~ N """' e ro "" ~-ã ~ '1'o ~ o o a; N o ;e '1'~ ~ o N ~ ~ ~ f;i E "' •• Ew o ro ;g-ã ~ ] -E oi E ~dl õ > .!1 o o ~ o N N c,'i!. ~ ID .,o ~ ;>: 2e •oo- •oE ~e ~ :g :§ "roo "- ~ 1' ~ ,.; o e o o- ª • B ',§ ~ *ii ~ o e ~ ;I " 1 ~ o 6 ;; ~ ~ 1 1 ~ ;;,,: +, REFERENCES Alcxandcr, O., Kennedy, M. and Kennedy, pp..334-5. J., 19$0. Rugby !cague footboll injuries ovcr lwo cornpctition scasons. Mcd J Aust, 2, Andrzcjcwski, M., Chmura, J., Str:r:ckzyk, R. and Konanki, J., 2012 lndMdualiz..tion of Physkal Loads and Spccd Abililics of Young Sncccr Pbycrs in a Six-Month Training Macrocydc. Joumal of Human Kinctks, 22(1), pp.35--U. Arcicro, l'.J., Smith, O.L. and Callcs-8candon, J., 199B. 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Champalgn, II.: Human Kindics. 1331 FITNESS IN SOCCER flTNESS IN SOCCER 332 1 Microcycle: Week planning Macrocycle: in-season 1 MICROCYCLE: WEEK PLANNING Werner Helsen, Jan Van Winckel, Paul Bradle'h Kenny McMillan 18.1 INTRODUCTION As was already mentioned in the previous chapters, weekly planning in soccer is entirely focused on preparing for the forthcoming match. At the beginning of each week, the emphasis is placed on recovering from the fatigue accrued during the previous match, while at the end of the microcycle, different tapering strategies are applied in arder to optimally prepare players for their next match. Only training sessions at least 48 hours prior to, or after, a match can be used to physically overload the players. 18.2 STRUCTURE OF A TRAINING SESSION A training session consists of the following parts: 1. Pre-activation or functional strength training 2. Warmup: 0 cardiovascular stimulus: - increase oxygen uptake - increase heart rate - activate the transportation of oxygen to the active muscles o dynamic stretching 0 speed: ATP-CP system and activate lactate removal (longer exertion with sufficient rest) 3. Technical/tactical training 4. Small-sided games (SSGs) 5. Progression phase: ln this phase, work is dane for each player individually based on a strength-weakness analysis; this can be technical (e.g., shooting, passing, receiving, etc.), tactical (e.g., line defense), mental, and physical (e.g., repeated sprint ability, speed, etc.) 6. Recovery phase: a cooling down a restoration of fluid balance • replenishment of energy substrates 1333 334 1 FITNESS IN SOCCER Microcycle: Week planning 7. Prevention phase: Prevention exercises are done in close collaboration with the sports science and medical staff: 0 increase active and dynamic flexibility (e.g., static, active, PNF method) 0 eliminate muscular maladaptations 0 restore muscular balances • increase proprioception 0 increase core strength 0 increase core balance 0 increase core endurance 0 other forms of injury prevention 18.3 PRE-ACTIVATION The warm up of all the different muscle groups (pre~activation) can be initiated in the dressing room ora specially designated roam, such as a gym or fitness roam if available, and it should focus particularly on the deep musculature. It is not always easy to properly warm up these musde groups in cold-weather conditions. The deep musculature serves as anchor points for the other muscle groups, so they must be well prepared. 18.4 WARM UP According to Bishop (2003), warm-up techniques can be broadly classified into two major categories: (i) passive \Varm up or (ii) active warm up. Passive warm up involves raising muscle temperature (Tm) or core temperature (Te) by some externai means (e.g., hot showers or baths, saunas, diathermy, and heating pads). Active warm up involves exercise and is likely to induce greater metabolic and cardiovascular changes than passive warm up. Active \varm up is probably the most \videly used warm-up technique. During the \Varm up, a player prepares various systems (cardiovascular, neural, pulmonary and muscular) for the lo ad they \Vill be subjected to in the game. An active warm up increases the total oxygen uptake and guarantees faster lactate elimination during training or a match. A passive warrn up, such as a hot bath, does not generate these effects. It is insufficient to merely warm the muscles to the right temperature. All the systems that are linked to oxygen transportation and consumption need to be activated before starting a match or traÍning session. Burnley et al. (2002) concluded that the V02 response to heavy exercise can be significantly altered by both sustained high-intensity submaximal exercise and short-duration sprint exercise. ln contrast, passive warnüng elevated muscle temperature but had no effect on the V0 2 response. Referring to the beneficial effects of increased temperatures on muscle extensibility, two studies by Shellock and Frentice (1985) and Strickler et ai. (1990) both suggest that a warm-up phase and dynamic stretching should always precede training to prevent stretching-induced injury. According to Shellock and Prentice (1985), most of the physiological effects of a warm up are temperature dependent. Mechanical efficiency of the muscle contraction is close to 20%, while most of the energy produced (70-80%) is thermal energy. Heat production by contracting muscles increases FITNESS IN SOCCER Microcycle: Week p/anning 1335 in the first minutes of the exercise (Krustrup et al., 2001). Most of the heat produced during the first seconds of exercise seems to accumulate in the contracting muscle, but after those first minutes, most of the produced heat is transported to the inner core by the blood or lyrnph drainage (Gonzales-Alonso et ai., 2000). An increased body temperature increases the amount of oxygen available in the working tissues, therefore helping oxygen to dissociate from hemoglobin and myoglobin. Moreover, an increase in rnuscle temperature reduces the time needed to reach the peak torque and the half-relaxation time of an electrically evoked twitch (Davies and Young, 1985; Sega! et al., 1986). The rnain aim of a warm up is to prepare the body for optirnal performance. Warm-up strategies are planned by coaching staff who rely on previous trial-and-error experiences (Bishop, 2003). A typical warrn up in soccer consists of 30-40 minutes of moderate- to high-intensity activities (Mohr et ai., 2004). This contrasts with research suggesting that 5-10 minutes at 40-70% of V0 2mnx is sufficient to improve performance (Bishop, 2003). However, coaches should take care and ensure that performance itself is not jeopardized by increasing pre-competition fatigue, decreasing blood glucose leveis and muscle glycogen stores, and prematurely elevating core temperature (Gregson et al., 2005). During the transition from rest to exercise, the body increases the oxygen supply to the muscles through the complex orchestration of pulmonary, cardiovascular and muscular processes. 336 FITNESS IN SOCCER 1 Microcyc/e: Week planning 18.4.1 Effects ofwarming up A thorough warm-up has the following effects: • The muscle temperature increases (39ºC). • Depending on the intensity and duration of the warm up, short-term performance is likely to be improved if the recovery interval allows phosphocreatine (PCr) stores to be significantly restored (Bishop, 2003). • The stroke volume of the heart, and the cardiac output increases. • Local vasodilation redistributes blood from the viscera to the working muscles. This redistribution of blood flow allows increased nutrient and oxygen delivery and improves the efficiency of waste product remova!. • The rise in temperature triggers enzyme activity, which increases the metabolism in the body, resulting in more energy being available for the muscles. • The quantity of oxygen-rich blood to the muscles increases, improving the metabolism in the muscles. o A warm up longer than ten minutes can impair long-term performance by decreasing muscle glycogen content (Gollnick et al., 1973) and/or decreasing heat-storage capacity (Gregson et al., 2002). • It is thought that the compliant muscle can be stretched further after warming up (Safran et ai., 1988). o Nerve conduction velocity increases, with the impulses reaching the muscles, tendons and ligaments faster. o Improved coordination. • Positive influence on the contraction and reflex times of the muscles. • The range of movement of the joints increases. • The muscles are better prepared for extreme movements with a high range of motion. • The risk of injury is reduced (Olsen et al., 2005). Grooms et al. (2013) investigated the effects of a soccer-specific warm-up program (F-MARC 11 +) on lower extremity injury incidence in male collegiate soccer players. They concluded that the F-MARC 11 + program reduced overall risk and severity of lower extremity injury when compared with controls in collegiate-aged male soccer athletes. • Higher rate of force development and therefore a decrease in time to peak torque. • Higher half-relaxation time. However, a warm up can also have negative effects, such as: • The glycogen reserves diminish: The substrates (muscle glycogen, blood glucose) will be used during the warm up. An excessively long warm up can therefore have a negative influence on performance. A warm up of 15-20 minutes is sufficient (depending on the outside temperature). • The body temperature could rise to dangerous levels (hyperthermia): In hot weather conditions, the body temperature can rise too high and affect performance.Ata body temperature above the critical temperature of approximately 40ºC, the body will limit performance in an attempt to prevent over- FITNESS IN SOCCER Microcyc/e: Week planning heating. Research has demonstrated that a hot and humid climate reduced short-sprint performance (Maxwell et al., 1999) and sprint time in a 90-minute soccer-specific protocol (Morris et al., 1998, 2000), as well as during an intermittent-sprint protocol on a bike (Noakes et al., 2001). • Muscular performance diminishes through extended static stretching. For example, the 20m-sprint performance of rugby union players decreased after static stretching (Fletcher and Jones, 2004). 18.4.2 Post-activation potentiation phenomenon Another physiological mechanism that helps clarify the increase in performance following a dynamic warm up is a phenomenon called post-activation potentiation (PAP). Following a short bout of high-intensity exercise (preload stimulus), the muscle is in both a fatigued and a potentiated state (referred to as post-activation potentiation). Consequently, subsequent muscle performance depends on the balance between these two factors (Kilduff et al., 2007). PAP refers to an increased power output following a specific stimulus (Robbings, 2005). For example, following a bout of dynamic exercise, the muscles show a clear enhancement in the rate of force development, such as jumping height. This period of improvement has been demonstrated to last between 5 and 20 minutes (Chiu et al., 2003). It seems that the majority of the enhancement is achieved in fast-twitch fibers (French et ai., 2003). Kilduff et ai. (2007) concluded that muscle performance in rngby (e.g., power) can be enhanced following a bout of heavy exercise (preload stimulus) in both the upper and the lower body in cases where adequate recovery (of 8-12 minutes) is given between the preload stimulus and performance. Till and Cooke (2009) found no significant group PAP effect on sprint and jump performance after both dynamic and isometric maximum voluntary contractions (MVCs) when compared with a control "\Varm-up protocol. However, the large variation in individual responses (-7.l~b to +8.2%) may suggest that PAP should be considered on an individual basis. 1 337 338 1 FITNESS IN SOCCER Microcycle: Week planning FITNESS IN SOCCER 1 339 Microcycle: Week planning 18.4.3 Structure of lhe warm up A warm up comprises four elements: cardio-vascular stimulus, dynamic stretching, speed, and initiation of V0 2 kinetics. 18.4.3.1 Cardiovascular stimu/us (5 minutes) This first phase entails light running with the aim of activating the cardiovascular (heart and blood vessels) and the pulmonary (oxygen) systems for intense exercise. This phase Iasts five minutes and involves light running only. Light passing and kicking exercises can also be used, with the emphasis on warming up rather than the speed and precision of the pass. 18.4.3.2 Dynamic stretc/Jing (5~10 minutes) Soccer is played in an open-air environment. When passive stretching is used, the muscles cool down again. It is therefore better to use dynamic stretching to prepare for a match or training session, particularly because soccer is a dynamic sport. Traditionally, many soccer players prepare for a match by performing extensive static stretching. However, static stretching only increases static flexibility and impairs performance. Although this does have a place in weekly training planning (as part of injury-prevention programs), it is better to use it at the end of a training session (see the following chapter). On a different note, some players still prefer to perform static stretching before a match, because that is how they have always done it, so they need it to mentally prepare before the game. Dynamic stretching is better for preparing the body for the movements needed during a match, although some players need time to do their own thing. Coaches will need to change the mind-set of these players by explaining the pros and cons of static versus dynamic stretching, but this will take some time-you cannot change it overnight. Mandengue et al. (2005) examined whether athletes •vere able to self-select their optimal warn1 up. They concluded that while most athletes could self-determine the intensity of their optimal \Varm up, some still needed guidance from others. 18.4.3.3 Speed The improvement of speed, agility and quickness is planned at the end of a warm up. The player is not fatigued yet, guaranteeing the quality of the speed training. A high-intensity exercise is carried out (for more than 15 seconds) after the speed training, follo•ved by a few minutes of recovery. 18.4.3.4 Starting V02 kinetics V0 2 kinetics has to be initiated during the warm up. This enables players to start the match without losing too much energy. 18.5 CENTRAL SECTION 18.5.1 Technical/tactical training. The first phase of the main section of training comprises technical/ tactical training. These exercises are kept as match specific as possible, of course, with the emphasis placed on correct execution of the technique. Each exercise must be properly incorporated into the periodization schedule. Both technical/ tactical training and match training have to be adapted accordingly. This can be done by increasing or reducing field sizes, incorporating additional running exercises, or adjusting the rotation system. 18.5.2 Match-specific exercises In the second phase of the central section, technical and tactical exercises are carried out in a match situation. Depending on the schedule for the season, these match exercises are modified in order to obtain the right intensity of physical exertion. Virtually every exercise can be adapted to the periodization requirements by adjusting distance, the number of players, or technical changes (e.g., the number of tou~ ches on the ball). 18.6 PROGRESSION PHASE Finally, in the progression phase, ali players work on their weaknesses. Each player is given an individual program, which can be technical, physical, mental and/or tactical. 18. 7 RECOVERY PHASE 18.7.1 Cool down There is a lack of scientific research on the physiological effects of a cool down. Exercise leads to an increase in body temperature, heart rate and blood pressure. There is also a buildup of waste and byproducts (e.g., lactate, creatine kinase) in the muscles. Furthermore, hormones, such as adrenaline and endorphins, are released into the circulatory system during exercise. If a player stops after training without executing a cool down, his leveis of circulating adrenaline and endorphins remain high. This can cause an aroused state or even a sleepless night. Players may not feel like doing a cool down after a strenuous game or training session, but they must understand that it is worth doing for the potential benefits, although scientific evidence is lacking for this. 18.7.2 Restoring lhe fluid balance Most players are already dehydrated before they start the morning training session. Fluid lost while sleeping is not restored because players often do not drink enough liquid with their breakfasts. In a study by Shirreffs and Maughan (1998), almost one-third (6/17) of the soccer players studied provided a pre-training urine sample with an osmolality above 900 mosmol/kg. These values may be indicative of a state of mild hypohydration before training began (Shirreffs and Maughan, 1998). Measuring body weight can give a good indication of hydration. The diffe- 340 1 FITNESS IN SOCCER Mícrocycle: Week planning 1341 FITNESS IN SOCCER Microcyc/e: Week planning rence between the typical body weight in the afternoon and the typical weight in the moming indicates how much extra water a player needs to drink. Fluid lost during the training session can be measured in the sarne \vay. It is assumed that a 1 kg loss of body mass is equal to a liter of sweat loss (Shirreffs et al., 2006). Maughan and colleagues (2005) investigated fluid and electrolyte balance in elite male soccer players training in a cool environment. The mean sweat loss during training was 1.69+0.45 L (a range of 1.06-2.65 L). The mean fluid intake during training was 423+215 ml (a range of 44-951 ml). The results of this study suggest that sweat loss may be substantial in soccer players training in a cool environment. The researchers speculate that because of adjustments in clothing, and perhaps also in activity levels, the total sweat and electrolyte losses may be similar to those experienced when training in hotter climates. Furthermore, fluid intake appears to be lower in teams training in the cold than it is in teams training in the heat. Training in a rain jacket, or other clothing, to deliberately cause weight loss during a training session is useless and potentially dangerous. This weight loss is simply a loss of fluid that should be restored immediately anyway. A player perspires to cool down the body. If this is hindered by wearing a rain jacket, the body temperature may rise to a dangerous level. 18.7.3 Replenishment of energy substrates There is an increase in the insulin levei immediately after training. This insulin is important because it stimulates protein synthesis. Therefore, this is an ideal moment to replenish the energy stores. The body absorbs carbohydrates and proteins more rapidly after physical exertion than in normal circumstances. According to Burke et al. (2006), each soccer player needs to equate daily carbohydrate intake to the fuel needs of the training and competition schedule. A reasonable target range for the carbohydrate intake of high-level players in less mobile roles, or teams or individuals with a less demanding training and competition schedules, is 5-7 g / kg/ day. For mobile players who want to maximize muscle glycogen refueling, such as in preparation for matches or for recovery during an intensive training schedule, a target of 7-10 g /kg/ day may be required. While there are some strategies to promote fuel availability for match play and prolonged training sessions by using nutritional practices on the day (Williams and Serratosa, 2006), tactics to restore (after intensive training) or even supercompensate muscle glycogen content must start 24-48 hours before a game. The importance of "fuelling up" before a match has been demonstrated in some publications. Balsom et al. (1999) examined the effect of a high-carbohydrate diet on performance. Participants follo\ved 48 hours of either a high- or low-carbohydrate diet before short-term (<10 min) and prolonged (>30 min) protocols of intermittent exercise (6s bouts at 30s intervals). Muscle glycogen concentrations \vere reduced by at least SO~'o in the low-carbohydrate trial compared with the high-carbohydrate triai, and there was an associated dramatic reduction in the work performed in both exercise protocols. 18.8 PREVENTION PHASE The prevention phase is executed on the pitch or in the fitness room. Players work to restore maladaptations and strengthen or improve deficiencies. For example, some players can strengthen their hamstrings (Nordic hamstrings), while others strengthen their abdominal muscles or do proprioception exercises (balancing exercises to train the neuromuscular system). The Nordic Hamstring exercise was developed by Mj0lsnes et al. (2004). This exercise, which can be dane on the field, has been demonstrated to increase the eccentric strength in the hamstring muscles of professional male soccer players. SUMMARY A typical training session consists of several different components. Before any technical/tactical training commences, pre-activation drills and warm-up exercises prepare the soccer player both physically and mentally for the forthcoming session. Thereafter, the main component of the training session usually consists of small-sided game play, technical and tactical drills, and individualized training programs. If possible, fitness improvement or maintenance should be a part of technical and tactical drills. The training session should end with a recovery phase to help the player prepare for the next training session. If time permits, individualized injury-prevention programs may then be canied out, as well as individualized strength training and flexibility programs. Strength training, flexibility training and injury-prevention strategies will be discussed in the following chapters. FITNESS IN SOCCER FITNESS IN SOCCER Microcycle: Week planning Stretching 1 STRETCHING REFERENCES Jan Van Winckel, Kenny McMillan, Werner Helsen, Paul Bradley, David Tenney Balsorn, P.D., Wood, K, Oh~oo, P. and Ekb!om, B., 1999b, Carbohydratc intnkcand rnultiplc sprint sports: With ~pccinl rcforcnre lo football fo<><=r). lntcmational Jouma! oi Sports Medicine, 20, ppAS-52. Bi>hop, D., 2003. Wann Up li: Pcrformanre Changcs FollowingActive W,irrn Up and How to Structurc lhe W,um Up. Sports Medicine, 33(7), pp.463-198. Burke L.M., Loucks, A.D. nnd Broad, N., 2006. Encrgy and carbohydratc for trainingand rccovery. Joumal ofSporls Scicnccs, 24(7), Bumlc;~ M,, Doust, J.H. and Jones, A.M., 2002. Effects of prior hcavy excrcioc, prior ~print cxcrcisc and pasoiw warmíng on oxygcn uptak kinctie> during hcavy cxcrcise in humnns. Eur J App! Phpio!., 87(4-5), pp.-12~-32Chiu, L.Z., Fry, A.C., Wci5s, L.W., Sdülling. !JK, Brown, L.E. and Smith, S.L., 2003. PostactÍ\.'1ltion potentiation responoc in 1lthletk 1lnd re<:reation.11ly traincd individuais. Joumal ofStrength and Conditioning Rcsean:h, 17(4), pp.671-577. Oavics, CT. and Young, K, 1985. Effect of heating on lhe contrnctile propcrtiesof trkcps ourae and mnximal powcr output duringjumping in e!derly mm. Gcrontology 31(1), pp.1-5. Ekstrand,J., GiUquist,]., Mllller, M.,Obcri;. D. and Liljcdnh~ S.O., 1983. !ncid<.'11roolsocccr injuries and thcirrel1tion lo!ralning .1nd tc.1m sucrcss. ThcAmerican joumal oi sport5 medicine, 11(2), pp.63-7. Fletcher, l.M. and )oni.-5, n., 200.J, The !lffcct of Different Warm-Up Stretch Protowls on 20-Mctcr Sprint PNformancc in Trained Rugby Unlon Playcrs.Joumal ofStl'<.'ngth and Conditioning Rc!lear<:h, 18(4), pp.8S5-S88. French, D.N., Kracmcr, W,J. and Cookc, CD., 2003. Chungcs in dynamk cxercioe performance following a oequenro of pn:conditioning ioomctricmusde ncliono:. Joum1ll ofStnmglh nnd Conditionlng Rcocar<:h, 17(4), pp.678-685 Gollnid:, f'.D., Armstrong. R.B. and Scmbrowkh, '\Y.L., 1973. Glyro;;cn dcplction pot1cm in human skclctal muscle fibrcr. 1lÍlor h~avy cxerdoc. JApp! Phyoiol, 34(5), pp 615-S GonOA1loz-Aloru;o, J., Qubtorff, B., KruMrup, P., Bangsbo, ). and SaHin, B., 2000. Hc.1! production in humon e.kckt.1! musclc at thc onnct of intcn.<e dynamic excrdoc. J !'hpiol, 52·1, pp.603-615. Greg,on, W., D,,t1crh.1m, ,\., Dru>t, B. and Cable, N.T., 2002. TI10 cffcct5 of prc-warmini:; on thc n1clobolic and thcrmorci:;ulatory reopon~ lo prolonscd intcrmittcnt el<crci,;c in modcrntc ambicnt tcmpernturcs. J Sporu Sci, 20(1), pp..19-50. Grod1inov~ky, A. and Ma gel,)., 1970. Effcct of warminr; upon running pcrformnn«'. Rcs Quart., .\1, pp.116-19. Groomr., DR., P.1lmcr. T,, Ona!c, j.A., Mycr, GD. and Grindr.taff, T., 2013. Sot(er-opcdfic warm·up and lowcr cxt...,mity injury rale:; m rol!egiale mnlc socccr ployers. J Ath! Trnin, -18(6), pp.782-9. H.1jog1ou, A, Fll.'",le~ C, DcKofiing, J.J, Ll!Cia ,A. Kcmozck, T.W. and Porca ri, J.P., 2005. Effrct of warm up on cyclc time triai pcrfor· mance. Mcd Sd Sports llxcn:., 37(9), pp.l&OS-14 Joni.-5, A.M. and Koppo, K., 2005. Eífoct ofTmining on V02 Kincli"' and performance. ln: A.M. Jon..., and D.C. Poolc, cdo. Oxyi;cn Uptakc Kincticr: inSport, Excrdr.e and Medicine. Abingdon:Taylor and Fmnds. p.JSS. Kilduff, L.P., Bcv.m, H.R., King5lcy, M.1., Owen, N./., Bennclt, M.A., Dunre, f'.J., Horc, A.M., Maw, j.R. and Cunningham D.],, 2007 Po.olaclivation potcnti,1tion in proícosional rugby plílycr,,;, oplimul rccovcry.J Slrcng~' Cond Rca, 21{·!), pp.113-Ml. Kruolrup, P., Gonzalcz·Alonoo, J., Qufotorff, B. nnd Bangsbo,]., 2001. Mur.dc hc1lt produclion and an~crobic cnergy tumovcr dunnr, "'PCíltcd intcnoe dynamic cxcrcisc in humans. j Physiol, 536, pp.9-17·956. Mandcnguc, S.H., Sock, O., Biohop, D., Cfos~, F., nala-Mbalo, P. and Ahmnidi, S., 2005. Are athlctesablc \oocH-.:clcct thciroplima! warm up? Joumol ofScicncc and Mcdidnc in Sport, 8(1), pp.26-34. Maughan, RJ., Shir...,ffo, S.M., Mcr<..on, S.j, and Hornwill, C. 1\., 2005. Fluid and elcctrolylc balanre in elite mal e football (socccr) playcro trainlng in a coo! cnvironmcnt. J SporIB5d., 23(1), pp.73-9, Maxwell, N.S., et al., 1999. Jntcrmittcnt runnini;; musde mctabolism in thc hcat and effect of hypohydmtion. Mcd. Sd. Sport~ D<cr., 231, pp.675-633. McCutchcon, Lj., Gcor, R.J. and Hinchdiff, K.W., 1999. F.lfccH• of priorcxcrd$C on muodc mctuboli~m during sprint c~cro!'.e in human~ J Appl Phyoiol, 87(5), pp.1914---22. Mjolr.ncs, R., Arnason, A., @5thagcn, T., Raa5t1ld, T. and Bahr, R., 200·1. A 10-wcck randomlzcd triai compMing ecccntric vs. ron.:>lnlrfr hamstring st...,ngth tralning in wcll-trnincd f>Ot:«'r playcrr,. Scandinavian Joum.1! Of Medicine (;; Scicnre ln 5porto, H(S), pp.311-317 Mohr, M., Krustrup, r., Nybo, L., Nich;cn, J.J. and 61lng~.bo, J., 200-l. Muode tcmpcralure ;md sprint pcrforman«' dunng r.oc.:>lr mal· cho;"".r-beneficial cffcct oi re-warm-up at half·limc. Scand J Mcd Sd Sports, H, pp.156--162. Morris,J.G., Ncvíll, M.ll., Lakomy, H.K.t\., Nichol"'l, C. and Wlllinm5, C., 1993. Effcct of a hotcnvironmcnton pcrformanroof proloni:;d. intcrmittent, high-intcnsity shultle running.Joumal ofSporW Socn«"o, 16, pp.677·686 Oh:.en, O.E., Mykkbust, G, Engcbrctr,cn, L., Holmc, 1. and D.1hr, R. 2005. fac reir"-"-' to preveni lowcr Iimb injuriC'J in youth sports: clustcr randomiscd controllcd triai. BMJ, 330(7459), p.449. Robbiru:, O.W., 2005. Po5tuctivation potcntiation and it5 practical applicability; a bricf revicw. loumal oi St...,ngth ;md Condilioninz Re~ean:h, 19(2), pp.453-15S. Safran, M.n., Scaber,A.V, and Gar...,u, W.E., 1989. \V,1rm-up and muocufar injury P"'vcntion:An updalc. Sports Medicine, S, pp.239-2·1? Saltln, B., Gngge, A.P. and Stolwijk,J.A.J., 1968. Musdc tcmpcrnlu"' during oubmaximal c~crdsc in man. 11\ppl Physiol, 25, pp.6;9-6&1 Shdlock, EG. and Prenticc, W.E., 19S5. Warming-up and stretching for improvcd physica! pcrforman<:e and pre\•cntionof sporl5·rdatcd injuries. Sports Mcd., 2(4), pp.267·78. Shirreffa, S.M. and Maughan, R.j., 1998. Urine 05molality and ronductlvily as markers of hydrnLion stalu5, Medicine and Scien«' ín SportG and Excrósc, 30, pp.1598-1602. Shirreffa, S.M., Sawk.1, M.N. and Stonc, M., 2006. Watcr and cle<:tro!ylc nccd5 for football training and match-p!.1y. /oumal of Sporb Scicn«"s, 24(07), pp.699-707. Stricklcr, T., Ma!onc, T. and GarrctL W.E., 1990. Thc dfocIB of pa,;,;i1•c warming on musdc injury. AmcricanJoumal of Sporw Mcdicin~, 18(2),pp.J.ll-t.15. Till, K.A. and Cooke C., 2009. Thc effcct.~ of postactivation potcntialion on sprint and jump performance of malc acadcmy socrer players. J St...,ngth Cond Ri.-5., 23(7), pp.1960-7. Williams, C. and Serra lo,.,, L., 2006. Nutrition on match day. Joumal oi Sports Sdcnet."l, 24, pp.687-697. 19.1 INTRODUCTION Stretching is a routine part of the training regime of soccer players. However, there is a great deal of controversy in relation to stretching. For a soccer coach, it is not easy to draw the right conclusions from the often-conflicting information available. Despite this problem, stretching has a long tradition of use, and it will likely continue to be a part of training and rehabilitation programs (Covert et al., 2010). Sh·etching can be beneficial to some extent, but we must try to emphasize a pragmatic perspective and use any scientific evidence to inform our judgments. It seems that the parameters of the stretch, such as the time to stretch and the holding duration, are almost as important as the stretching technique used. This chapter provides an overview of different stretching techniques and sets out how and \vhen these techniques can be used. 19.2 TYPES OF STRETCHING 19.2.1 Ballistic or elastic stretching Ballistic stretching is a form of stretching performed in a bouncing motion, using the momenhtm of a moving body or limb to attempt to force it beyond its normal range of motion. This type of stretching is likely to increase flexibility through a neurological mechanism. It involves fast "bouncing" movements where a double bounce is performed at the end range of movement. Ballistic stretching should only be used by athletes who know their limitations and who are supervised by staff. Some shtdies have expressed concerns over the risk of muscle-strain injuries (Vujnovic and Dawson, 2004), because ballistic stretching could potentially cause microtrauma to the muscle (Taylor et aL, 2004). These hypotheses are not supported by current scientific literature, but nevertheless, coaches should be careful about using ballistic stretching after soccer activities that could cause EIMD (e.g., excessive eccentric loading, match play, etc.). Soccer players need time to recover from these activities, and they should not attempt to improve flexibility while in this state. 1343 344 1 FITNESS IN SOCCER FITNESS IN SOCCER Stretching 1345 Stretchíng 19.2.4 Passive stretching or static stretching 19.2.2 Dynamic stretching This type of stretching is not to be confused with ballistic stretching. Although the manual of the American College of Sports Medicine puts dynamic stretching on a par with ballistic stretching, there is a distinct difference between the two. ln contrast to ballistic stretching, dynamic stretching steadily develops the movement sequence, guaranteeing a gradual buildup in the warm-up process. Research shows that dynamic stretching is most effective \vhen the emphasis is on the greatest amplitude or range of motion rather than the greatest movement velocity. Dynamic stretching improves flexibility to the sarne degree as static stretching (Beedle and Mann, 2007), although O'Sullivan an<l co-workers postulate that <lynamic stretching is less efficient at increasing static flexibility than static stretching is (O'Sullivan et al., 2009). Dynamic stretching is a useful protocol for increasing flexibility and increasing performance. Hovvever, it is unclear whether this effect is brought about by the stretching or the warming up associated with it. Regardless, it is advisable to carry out <lynamic stretching before a match and/ or training session. 19.2.3 Aclive stretching Active stretching is also referred to as static-active stretching. ln this type of stretching, a part of the body is move<l into a particular position using agonist muscle strength. The antagonist is then stretche<l. This increases active flexibility and strengthens the antagonist at the sarne time. It is consi<lered to have a lower risk because players contrai the stretch force with their own strength rather than an externai force. Example: The player stands still and raises his or her leg si<leways; the abductors (agonists) are then activated, and the adductors (antagonists) are stretched (Fig. 19.1). Passive stretching is also referre<l to as relaxing or static-passive stretching. ln this technique, stretching is carried out \Vith the help of another part of the body, a partner, or an auxiliary aid. ln some books, passive and static stretching are separated. The difference is that in static stretching, the muscle is moved to a particular position and held, \Vhile in passive stretching, a particular position is achieved \vith the help of an auxiliary aid or another person. Static stretching increases static flexibility (Pov.'er et al., 2004) but does not affect dynamic flexibility (Halbertsma et al., 1996; McNair et al., 2000). Various studies have demonstrated that static stretching has a negative effect on performance (Behm and Kibele, 2007), as \Vell as a negative effect on reaction time, n1ovement time and balance (Behm et al., 2004). Bandy et al. (1997) demonstrated that performing static stretching three times a day did not induce significantly different gains in flexibility \Vhen compared to stretching only once aday. Fig. 19.2: Example of passíve stretchíng. A great deal of research has been conducted into the effects of static stretching on performance. It can generally be said that static stretching prior to a n1atch has no effect, or possibly even a negative effect, on performance. T\VO highly cited revie\VS (Behm and Chaouachi, 2011; Kay and Blazevitch, 2012) both suggest there is a duration effect on the impairments associated \Vith stretchíng. If more than 60-90s of static stretching is perforn1ed on a single muscle group, it seems likely the player \Vill suffer perforn1ance impairments. Less than 30s of stretching per muscle group can still result in deficits, but the research is conflicting about this, so a player is less Jikely to suffer deficits \vith short durations of static stretching. It is not yet clear \vhether a \Varm up after thís static stretching can reduce the negative effects. Overall, static stretching should be avoided prior to the start of a match or training session. Fig. 19.1: Example of active stretching. Fig. 19.3: Passive stretchíng. 346 FITNESS IN SOCCER Stretching 1347 1 FITNESS IN SOCCER Stretching Example of the PNF n1ethod. The player \Vorks his quadriceps by bending his leg, after \Vhich the leg is allo\ved to relax for 10 seconds. The muscle is then finally stretched for 10 seconds. Fig. 19.4: Stat1c stretcl1ing. The calf musc/es of the rear feg are stretched. The externa! a.id here is the floor. ln the picture on the /eft, it is maínly t11e deeper calf muscfes lhat are stretched, and m 1/Je right-hand photo, it is mainly the superficial calf musc/es. 19.2.5 PNF method (proprioceptive neuromuscular facilitation) There are various forros of the PNF method (reversal-hold, contract-relax, hold-relax, slo\v-reversal-hold). These techniques all consist of the combination of alternating the contraction and relaxation of agonist and antagonist 1nuscles (Shellock and Frentice, 1985; Burke et ai., 2000). PNF methods are complicated stretching techniques, and they need experience to be performed. The use of the PNF technique prior to match play or training is still questioned, and although PNF stretching has been reported to result in an increased range of motion when compared to static stretching (Magnusson et al., 1996), it remains a questionas to whether this also involves dynamic flexibility. Example of the PNF method. The player holds his foot \vhile trying to straighten his leg. The leg is then relaxed for 10 seconds and finally stretched again for another 10 seconds. Fig. 19.5: PNF stretching Fíg. 19.6 19.3 INCREASING FLEXIBILITY OR PREPARING THE BODY When using stretching techniques, it is important to know in what context and in \vhat \vay these techniques should be used. For example, prolonged static stretching is detrimental to performance if applied before a match. Ho\vever, if the technique vvere used in a flexibility session to increase suppleness, it could lead to fewer injuries in soccer. Dynamic stretching is optimal for warming up before a soccer game. In arder to increase the range of movement, ho\vever, the use of static stretching is preferred (Little and Williams, 2003). 19.3.1 Flexibility ln a large number of sports, flexible muscles are needed to enable optimal performance and prevent injuries. Sports that require flexible muscles include basketball, volleyball and soccer. These are sports in 1vhich an SSC (stretch-shortening cycle) is used. This 1neans that a muscle is first used eccentrically in order to then be used concentrically. A good example of an SSC is a jump in \vhich the knees are first bent in order to then be able to jutnp higher. Flexible n1uscles are needed in these sports to convert the energy stored in the muscle duríng the eccentric action (bending the knees) into concentríc action (the jump itself). ln a study of Walshe and Wilson (1997), athletes had to perform a jun1p after they jun1ped from a bench of 80-100 cn1. The results den1onstrate that flexible players jump significantly higher than less flexible players do. On the other hand, Walshe and Wilson (1997) found that the most flexible athletes experience more injuries than moderately flexible athletes. Depending on the action, certain sports need less flexibility than others. Increased flexibility can even hinder performance in some cases. Sprinters, for example, need 348 J FITNESS IN SOCCER FITNESS IN SOCCER Stretching to transfer the SSC very rapidly (vvithin 200ms), soa more taut muscle is better able to transfer this energy quick1y. When the running distance and the contact time on the ground is two to three times longer than in sprinting, a n1ore flexible musculo-tendinous unit is needed to store the elastic energy over a longer period and return it to the action at the appropriate time. To make the situation even more complex, very flexible athletes (hyperlaxity or hypermobility) are more prone to sprain-type injuries. 19.3.2 Preparing the body for a match or training The body must be prepared to perform before the start of a match or training session. Players therefore have to call on the different systems (i.e., cardiovascular, respiratory, neural, muscular) to ensure they are ready to perform. The body needs time to fully initiate oxygen uptake (VO, kinetics). In addition, the temperature of the muscles needs to increase by 1-2 deirees. Finally, the muscles also need to be prepared for extreme movements, such as sh·etching to controla bar in the air. However, coaches should use a different technique in this regard rather than that applied for increasing the flexibility of the inuscles. It is therefore recommended to use dynamic stretching before the start of a n1atch. This technique increases the ten1perature of the muscles and prepares the body for optimal performance ata high level. 19.3.3 What techniques do we use and why? There is a great <leal of literature available in scientific journals. Although they sometimes give conflicting information, we can nevertheless dra\V the follo\ving conclusions: 0 Static stretching may be detrimental to performance. In a study of Gelen, static stretching before a slalon1 ball dribbling test reduced performance by 8.Sjo (Gelen, 2010). 0 Static stretching increases the flexibilíty of the muscle. 0 Brief static stretching (< 30s) is Iess detrimental to performance. Research demonstrated that 36" (6 repetitions of 6") of static stretching increases the ROM significantly (Murphy et al., 2010). Another study sho\ved that a minute of static stretching caused less performance degradation than two or four minutes of stretching (Young et a1., 2006). 0 The muscle cools down again during static or passive stretching, and the cardiovascular and respiratory systen1s return to rest status. ª Dynamic stretching either has no detrin1ental effect or improves performance. 0 Intensive dynamic stretching is better than less intensive stretching. 0 Static stretching to the POD (i.e., Point Of Discomfort: the point at ovhich the athlete indicates that the stretching feels uncomfortable) has negative effects on strength performance (Behm et al., 2006). Static stretching up to 90 1;~ of POD reduces the adverse effects of static stretching on performance (Manoel et al., 2008). Based on existing literature, it is clear that static stretching should not be used before the start of a match. Instead, (intensive) dynamic stretching should be used to prepare the players. To increase the flexibility of the muscles, it is therefore recommended to incorporate flexibility training after the end of a training session or in a specific session. Stretching 19.4 USE DURING THE TRAINING WEEK 19.4.1 Warm up before a match ortraining session The aim of the warm up is to prepare the body for physical activity. The players must therefore activate the various systems (i.e., cardiovascular, pulmonary, neural, and inuscular) to ensure they can use these efficiently during the match or training session. On the other hand, the muscles also have to be prepared for extreme movements during a match ar training session. This could be a sliding tackle, for example, where the adductors (groin) are stretched to the extreme. For this reason, dynamic stretching is used at the beginning of a training session or match. These types of exercises stretch the muscles sufficiently, thus preparing them for extreme movements. Torres et al. (2008) suggest that dynamic stretching in a warm up is better than static stretching because the movements are specific to sport. Examples: • Skipping 0 • Carioca - Knee pull-ups -Sidesteps - Swinging the arms 19.4.2 lnjury prevention Long-term development of flexibility is important for injury prevention, so flexibility practices must be carried out through the season. Witvrou\v et al. (2003) and Bradley and Portas (2007) also found that hamstring muscle-strain injuries in elite players correlated significantly with lo\V hamstring flexibility in preseason. Witvrouw et al. (2003) also reported that the decreased flexibility of the quadriceps muscles should be considered an intrinsic risk factor for injury. Screening of flexibility for players should be conducted during preseason, and flexibility training should be prescribed to players ovith reduced flexibility to lower the risk of developing a muscle-strain injury. That said, one must be pragmatic about this and realize that many other factors contribute to injuries in complex sports like soccer. 19.4.3 Jmportant stretching guidelines for static stretching ª Never stretch \Vithout first getting the muscles to the right temperature, such as by spending a fe\v minutes jogging (a minimum of five minutes). ª Ensure the correct starting position and correct execution. 0 Ensure a stable starting position. ª Findas many support points as possible. ª Stretch the muscle (group) slo\vly. ª Stretch until you feel some tension in the muscle (no pain). • Hold this position for 10-20 seconds. • Take care to continue breathing calmly and rhythmically. ° Concentrate on the muscle being stretched and check the tension. ª Return from the stretching position slo\vly. 0 Repeat each exercise several times. 0 All exercises should be done for both the left and the right side. 0 Perform stretching techniques in a sufficiently warm roam. 1349 FITNESS IN SOCCER FITNESS IN SOCCER Strength trainíng and functional traíning Stretching SUMMARY Stretching has a long tradition of use in soccer training programs, and this trend will likely continue in n1odem soccer training. There is some evidence that prolonged static stretching before explosive power movements may be counter-productive. Therefore, it is advocated that intense dyna1nic stretching should be preferably performed before a match or training session. ln addition to enhancing performance, the long-term development of flexibility may also be important for inju1y-prevention purposes. Physiotherapists should routinely perform flexibility screening, so that tight, inflexible muscles can be identified and appropriate stretching exercises advocated. Static stretching performed after soccer training seems the most suitable form of stretching for improving the long~term flexibility of a soccer player's musculature. STRENGTH TRAINING AND FUNCTIONAL TRAINING Lieven De Veirman, Glen Reed, Pieter Jacobs, Jan Van Winckel 20.1 INTRODUCTION REfERENCES Alter, M.J., 19%. Scicncc of flexibility Chompalgn, IL: Human Kinclíe5 Pubfü;hero. llandy, W.D., lrion,J.M and Brigglcr M., 1997. ThcdfoctoftJmcand frcqucm:yofst,1ticst"'lchingonflexibihtyofthe hamstring muodcs Phy~kal Thcmpy, i7, pp.lO'Xl-1096. llcedlc, ll.ll, and Mann, C.L, 2007. Acomparison of two m1rm up:; on joint range of motion.J Strcngth Cond Rcs, 21, pp.77ú-i79. lldun, D.G, llambury, A., C.1lü!I, F, and Powcr, K., 200·1. Eficct of arutc·stalic slrctchmg on forre, balam:e, "'action time, and mo,·cmcnt time. Mcd Sci Sports Excrc, 36, pp.1397-1-102. llchm, D.G., füadbury, E.E., Harncs, A.T., Hoddcr,J.N,, Lconard,A.M. and P,1ddock, N.R., 2006. Flcxibi!ity fonot rcfatcd loslrctch-lndu· ccd deficit> in fon:c or powcr. J Sports Sd Mcd, 5, pp.33-12. Bchm, D.G. and Kibclc, A, 2007. Effccts of d1ficring in1cnsitics of 5\atic strctchini; on jump performance. Eur J Appl Physiol, 101, pp.557-594. llchm, D.G. and dlaouad>~ A., 2011. A rcvicw of thc ac;utc elfrcts of ~latk and dynamicstrctdting on pcrlormanre. Eur / Appl Phydol, 111(11), pp.2633-2651. llr.1dlcj; ~ and Portao, M.D., 2007. Thc rc!Jtiunship bctwcen preocaoon rnngc of motion and mu~clc strain injury in elite ,;occcr playcm. Jouma! of Strcnglh & Conditionlng Rc,;.:,arch, 21(·1), pp. 1155·1159. Cowo1n, D., Joncs, ll., Tomliru;0n, P., Robin5on, J, and Polly, D., 1988. Thc cpidcmiology of phyoknl training injuries ln US lnfontry trainc<'S: mcthodology; popufation, and riol: factors. USArmy Rcscarch lrutitutc of Envlronmcntal Medicine Tcchnolog)', NO:T>!-89, CovNt, C.A., A!cxandcr, M.P., Pctronir,, j.j. and D,wi,, D.S., 2010. Comparison of balfütic and slatiç fitrctching on hamstring musdc lcnr;th u~ing anequal strclchlng dow.] Strength Cond Rc;;, 24(11), pp.300S-3014. Gclcn, E., 2010. Ac:utc cfforu; of diffcrcnt warm-up mcthods on sprinl, slalom dribb!ing. and pcnalty kick perform1mcc in wcccr playcrs. / Strcngth Cond R<'S, 24, pp.950-956. Halbcrtsma, J.P., van llolhuis, A.1. and Gockcn, LN., 1996. Sport strctching: cffcct on p,,,;sivc musclc stifínc~,; in short ham~trings of hcalthy subjcctfi. Archivco of Physicnl Medicine and Rehabilitation 77(7), pp.6SS--692. Kay, A. and Bla:wvich, T., 2012. Effoct oi ac;ulc staticslreh;hon maximal musdc pcrformnncc: Asystcmatic revicw. Medicine and Sdcncc inSports and Excrdsc, 4.\(1), pp.15-1--lM, Littlc, T. and Williamr., A. 2003. Spcdficity of accelcrntlon, ma~imum specd and agility ln profcwional oom:r playcrs. j Strcngth Comi Rcs., 19(1), pp.76-11. Mugnuo>an, S.P., Simonscn, E.B.,Augaard, P., Drhn.'-Poulr.cn, P., McHugh, M.P. and Kjuer, M., 1996. Mcchankal and physica! n.-sponscs to 5lretching with and wl~lOut prcisomctric rontruclion in human okelclal muodc. Archivcs of Phpical Medicine and Rchabihtation, 77, pp.373-378. Manoel, M.E., Hílrris-Ltwe, M.O., Danoff, ).V. nnd Miller, T.A., 200S.Acutccfíccw oi static, drnumh:, and proprio<:eplivc ncuromu"rulílr facilitation olrctdtingon musdc power in womcn. J Strcnglh Cond Res, 22, pp.1528-153-1. /\-kNair, P.J., Dombrooki, E.W., Hcwson, D.J and Stanley, S.N., 2000. Strclching at thc anklc joint: vi>eoclu~ticrcsponsl!S to holdo ílnd con· tlnuous pa~~ivc motion. Mcdicineand Scicncc inSports and Excrdoe, 33, pp.354·355. Murphy, j.R., Di Santo, M.C., Alkanani, T. and Bdun, D.G., 2010. Activity ~forc and followingshor! duration st.1tlcstrctd1ini; improves range of molion vs. a lraditional warm-up. Appl Physiol Nutr Mctab,35, pp.l-12. O'Sullivan, K., Murray, E. and Sninsbury, D., 2009. Thccffcd ofwarm-up, otatkiltretching and dyn.1mic stretching on hamstring flcxíbility in prcviously injured subjL"<:ts. ll!\lC Musc:uloskclct Disord, 10, pp.37-12 Powcr, K., lldun, D., Cahill, F., Carrol!, M. and Young, W. 200<1. An nc:ulc bout of static slrctching: cfíecl5 on foro! and jumping p~rfor· mancc. Mcd Sd Sports Exerc, 36, pp.1359-1396. She!!ock, F.G. (:!'rentice, WX. 1985. W.lrm up and slrctching for lmprovcd physical performance and prcvcnlion of sporl'l-rclatcd inju· rico. Spls. Mcd., 2, pp.267-278. Taylor, W., Hcller, M., llcrgmann, G. and Duda, G., 200-l. Tíbio-Femoral Loading During Human Ga1t and St,1ir Climbing. Joumul of Orthopacdic R~.,;carch, 22, pp.625-632. Torre;, E.M., Kracmcr, W,]., Vlngrcn,J.l., Volck, j.S., Hatficld, D.L, Spiering. B.A., Ho, JX, Frupla, M.S., Thomas, G.A., Andcrson, J.M., Hakkinen, K. and Maresh, CM., 2008. Eficctsofstrdching on up~rbody muscular performance.] Strcni;th Cond Res, 22, pp.127()..1285. W"lshc, A.D. and Wilson, G.J., 1997. Thc influcncc of musrulotcndinous stiffnC""..5 on drop jump performance. Can] Appl Phy~iol, 22, pp.117-132. Witvrouw, E., Dannecls, L., A=lman, ['., D'l·!avc, T. and Cnmbícr, D., 2003. Musdc flcxibilily asa ri~l:factor fordcvclopingmusde lnju· rics in mate profo,;:;ional oocccr playcrs: A proopective study. Amcrican Joum.11 of Sporls Medicine, 31{1), pp.41-46. Young. W., Clothier, P., Otago, l., Bruce, L., and liddcl!, D. 200.1. Acutcdicctsofstaticstrctdting on hip flexor and quaciriCl.'psflcxibility, rangcof motion and foot ~pecd ln k.kkinga wccer.J Sei Mcd Sporl, 7(1), pp.23-31. Young, W., Elias, G. and Powcr, )., 2006. Eficcls of static stretdting volume and inlcnsity on plantar flcxorcxp!csivc force production und range of motion. / Sport Mcd Phys Fitncss, 46, pp.403-\11. Strength training has evolved tremendously over the Iast decennia, with a great <leal of research trying to establish the fundamental principles of strength training. Speed-strength (power) is often a decisive factor in modern soccer. Concurrently, the somatotype of soccer players has also changed over the last few decades from ectomorphic (e.g., Cruyff, van Basten, Platini) to more mesomorphic athletes (e.g., Ibrahimovic, Ronaldo, Kompany, Rooney). ln this chapter, we discuss the physiology of muscle strength and the various strength training programs. 20.2 PHYSIOLOGY OF MUSCLE STRENGTH 20.2.1 Muscle fibers The human body has different types of muscle fiber. The ratio of these muscle fibers is certainly not identical in all muscles. sport discipline ºlo ST-fibers ºlo FT~fibers Distance runners 70-75 25-30 Swimmers 55-65 35-45 100 m sprinters 25-30 70-75 Weight lifters 45-55 45-55 Non-athletes 47-53 47-53 Soccer players 40-55 45-60 Table 20. 1: Muscfe fiber composition in different sporls. FACULDAD~ OE DESPORT01 DA UNIVERSIDADE DO PORTO 1351 352 1 FITNESS IN SOCCER FITNESS IN SOCCER Strength training and functional training Strength training and functional training Muscle fibers can be generally classified in hvo ways. On the one hand, they can be classified based on the mATPase, but they can also be classified based on the myosin heavy chain (MyHC) isoform identification. Based on the activity of myosine ATPase, muscle fibers are classified as slo•v oxidative (or type I fibers), fast glycolytic (or type Ilb fibers), and fast oxidative (or type Ila fibers). Myosin, more specifically the MyHC, is composed of three different forms or isoforms. Based on the identification of the MyHC isoforms present in the n1uscle fibers, the MyHC forms (MyHC !, MyHC IIA, and MyHC IIX [often referred to as IIB in older literature}) can be identified. However, there are muscle fibers in •vhich more than one form of MyHC occurs, and these hybrids contain hvo different MyHC forn1s in different proportions. Based on MyHC, •ve can distinguish six different muscle fibers in a continuum from slow to fast: I, IC, IIC, IIA, Ilax and IIX. 20.2.2 Muscle architecture Muscle strength is dependent on the cross-sectional surface area of a muscle. When muscle strength is expressed in strength per cm2, it does not differ all that much bet\veen untrained athletes and those who have undergone extensive strength training. It an1ounts to around 6.3 kg/ cm2 in both cases. The difference in strength can be predominantly attributed to a larger cross-sectional surface area. Fusõform Pennate 20.2.3 Stretch-shortening cycle The strength of a muscle increases (by 15%.) if it is pre-stretched (Cavagna and Cittero, 1974; Bobbert et al., 1996, Bobbert and Casius, 2005). This can be seen •vhen jun1ping, for example, in a counter-movement jump (CMJ) where the muscles are first extended (bending the knees) and then stretched again (knees straightened). If a muscle isn't pre-stretched, such as in a squat ju1np (SJ), the movement is n1ore strength based. a d ! " a J g l 20.3 STRENGTH TRAINING ANO THE NERVOUS SYSTEM It ís often wrongly believed that muscular adaptations from training take place solely within the 1nuscle itself. Ho•veve1~ strength is generated by muscles that are, in turn, governed by the central nervous system. The central nervous system decides ho•v many n1uscle units are recruited and whether synergist 1nuscles might be involved. It can also disable the antagonists or reduce their effects. The central nervous system thus activates, synergizes and inhibits the n1uscles responsible for a moven1ent. Short stimulations of a few milliseconds provide for subdued movement, while constant stin1ulation of the muscles can facílitate longer movement. Strength --- Fig. 20, 1: Comparison of lhe surface are a of lhe actin and myosin fi/aments The sum of the actin and myosin fi/aments, the proteins responsibfe for the contraction of a musc/e fiber, is almost double for a pennate musc/e compared with a fusiform muscle. Muscle strength also depends on the architecture of the muscle fibers. This is the arrangement of muscle fibers, and it determines a muscle's mechanical function. Several different n1uscle architectures are described in the scientific literature, such as triangular (m. pectoralis n1ajor), (uni)pennate (m. semimembranosus) and fusiform (n1. sartorius). Force production and gearing vary depending on the different geometries of the muscle (Moreau et al., 2010). ln the rectus femoris (part of the quadriceps) and the gastrocnenüus muscle (part of the calf)-both of which are unipennate, and bipennate muscles respectively-the muscle fibers have a featherlike structure that aln1ost doubles the muscular strength. " Fig. 20.2: Difference between a CMJ and SJ. An SJ starts in an afready loaded position, and there is no stretch-shortening ability to provide power. Hypertrophy Neural Time Fig. 20.3: Adaptations through strength training: lnfluence of training on strength, hypertrophy and neural adaptation. 1353 354 1 FITNESS IN SOCCER FITNESS IN SOCCER Strength trainíng and functional traíníng 1355 Strength training and functional training Results will be achieved quickly at the start of the training program. It is therefore also in this period that new reference values need to be determined at regular intervals in arder to fine tune the strength training program. Strength training also rnakes the muscles thicker (hypertrophy) over the course of time because of more sarcomeres coming together. The nervous system not only provides for the movement itself; it can also learn to engage motor units faster during a particular movement. Finally, the nervous system ensures maximum efficiency during a particular movement. It activates the right motor units and makes them respond at just the right moment. The good news is that these activities performed by the central nervous system can be trained, but the training of isolated movements only teaches the nervous system to perform the movement in question at the sarne angle and at the sarne speed. For this reason, muscles need to be trained in a natural movement pattern during training sessions. To increase kicking speed, for example, it would be insufficient to simply train the strength of the quadriceps muscle. Although the strength of the quadriceps may \vell increase, it will not result in greater kicking speed, because the movement was not trained in an synergized way where all the muscles (e.g., quadriceps, hamstrings, etc.) produce the movement together. However, some strength exercises do provide a crossover to sporting activities. Many authors (Balsom et ai., 1992; Wisloff, Helgerud and Hoff, 1998; Hoff, Berdahl and Barten, 2001; Hoff, Gran and Helgerud, 2002; Wisloff et al., 2004; Deane et al., 2005; Stone et aL, 2006) have found evidence of increased strength levels correlating to improved performance parameters. Four types of strength can be distinguished: maximal strength: The capacity of a muscle or muscle group to execute maximum strength against a resistance in one contraction explosive strength (power): The capacity of a muscle to overcome a relatively high resistance as quickly as possible (e.g., ln the first phase of a sprint, the quadriceps need to use explosive strength to start the sprint.) strength endurance: The capacity of a muscle or muscle group to exert maximum strength over a certain period (e.g., consider running, where the muscles of the body perform one and the sarne action) speed strength: The capacity of a muscle to overcome a relatively small resistance as quickly as possible These parameters can be easily interpreted via the Force-Velocity curve (Seen in Figure 20.4). IBench press Bencll press throw '-----!· lSquat i iPush·up c!ops ! ISqu<it sn11tch (l.e., bar stilrts 1Powcr snatcll from hang (l.c., bar ~rom tllc floor and cotch takcn 1st11rts from abovc the knees ilnd dccp squilt pos1tion) ic;•itcll takcn in 1/4 squot position) Seoted medicine boll throws IBox Jumps 1in "S~"-º"~"7'_'_'"-'"-'-'-"C~!'~º-"-º"-"------+iP_o_w_oc_'_''-º"_fro_m_h'_"~º-___.;!_Boun.d !_"9____~ IShou!dcr prcss Push press iSplit Jerk 0 wheelbarrow 1 Tab/e 20.2: Exercise exampfes ofthe force-velocity curve, taken from Turner (2009). 20.5 TYPES OF STRENGTH TRAINING 20.4 TYPES OF STRENGTH These four types of strength can be used in different strength training sessions, with each having a different objective: general strength training: These are the normal weight-training exercises that strengthen the muscles and connective tissues. specific or functional strength training: This type of strength training is as close as possible to the biomechanical requirements of the activity. preventive strength training: This type of strength training places an additional load on particular muscle groups in order to reduce the risk of injury. Maximal strength Strength-speed Power Speed-strength Velocity Fig. 20.4: The Force-Ve/ocity CuNe, which highfights lhe difference between the different training modalities 20.6 PLYOMETRICS Plyometrics is a special form of strength training. Plyometrics has its roots in the former Eastern Bloc, where it was known as shock training. The term "plyometric" comes from Latin, with the words "ply" representing progress and "metric" signifying a measuring rod. Plyometrics is a training form that uses fast, explosive exercises to improve power· output and the neural (nerve) activation of the muscles. Plyometrics is based on the physiological phenomenon of the stretch-shortening cycle (SSC), which, as mentioned above, is based on the principie that when a muscle stretches quickly and then contracts, the power the muscle can produce increases. The receptors Iocated in a muscle respond to the information that a muscle is getting longer. ln the eccentric phase, the muscle stretches, and the elastic energy is stored in the "series elastic FITNESS IN SOCCER 356 1 Strengtl1 training and functional training FITNESS IN SOCCER Strength training and functional training component" (SEC) and the muscle spindles become activated. The amortization phase is the time behveen the eccentric and concentric motions, and during this phase, the type la afferent nerves synapse with the alpha motor neurons. These alpha n1otor neurons then transmit signals to the agonist muscle group. Once the amortization phase is co1nplete, the concentric action occurs, which is the shortening of the agonist muscle fibers. This causes the elastic energy to be released from the SEC while the alpha motor neurons stimulate the agonist muscle group. Wilson, Elliot and Wood (1991) found that the SSC had a half-life of 0.85 seconds and that a contact time of over 1 second dissipated the effect of the SSC by over 55%. This finding is further supported by Cronin, McNair and Marshall (2002), who found that the SSC has to be utilized within 0.2 seconds to prevent the effect from being lost. This is \vhy a short amortization phase is essential. The mechanical model for musclotendínous behavior has a contractile element (CE), which exerts active force during shortening; a series elastic component (SEC), which serves to store the energy and later release it; and finally a parallel elastic component (PEC), \Vhich stores the elastic energy in parallel to the contractile component of the muscle (Bosco et al., 1982). The quantification of plyometric exercise has recently been assessed via the measure of the reactive strength índex (RSI). The RSI is derived from the height jumped in a depth jump and the time spent on the ground developing the forces required for the jump (McClymont, 2008). A low RSI score essentially means an individual can quickly change behveen an eccentric and concentric contraction (Flanagan and Comyns, 2008). An athlete with a good SSC ability \vill be able to tolerate a higher load in the forro of a higher drop jump. i Jump Height (m) Reactive Strength ~ ln dex Ground Contact Time (s) Fig. 20. 6: Formula for ca/culating the RSI. An RSI can be increased by increasing jump height andl or decreasing contact time PE (((((y(l' FORCE CE Fig. 20.5: Hilfs (1938) three-component model highfighting the interaction between Contractile (CE), Paraflel (PEC) and Series efastic components (SEC). Schmidtbleicher (1994) divided the SSC into t\vo types: short and long SSC. Short SSC includes a ground contact time (GCT) of <250ms, involves small angles, and is represented by exercises such as the drop jump or sprinting. A longer GCT (>250ms) represents long SSC, where greater body angles are seen, such as is evident in exercises like jump shots. There is plenty of evidence to support the use of plyon1etrics to increase performance characteristics like running economy, sprint speed, and jump height, to nan1e but a few (Myer et al., 2006; Potteiger et al., 1999; Rimmer and Sleivert, 2000; Spurs, Murphy and Watsford, 2003; Turne1~ Ü\vings and Schwane, 2003, Paavolainen et al., 1999; Vossen et al., 2000). Nevertheless, plyometrics is not applied that often. This is not only due to a Jack of knowledge but also to the fact that plyometric exerdses need to be prescribed wíth the necessary scientific background. The normal method is to vvork \vith the body i;veight, \vhich means that n1ore than 70 kg of i;veight is used as the load for an adult man. Correct execution and the right feedback are therefore very important. 1 ~ ~ Flanningan and Comyns (2008), proposed that strength and conditioning coaches can determine the optimu1n height for depth-jump activity by using RSI over a range of jump heights (e.g., 15, 30, 45cm). If the RSI is either maintained or improved by increasing depth-jump drop height, then it can be assumed that the individual's reactive strength capabilities are sufficient for that jump height. If the RSI decreases ata certain drop height, it i;vill be beyond the fast SSC threshold, and this may indicate a heightened risk of injury. Flanagan and Comyns (2008) designed a four-phase model for the progression of fast SSC exercise. A progressive program is required to ensure all movements are performed using a correct technique because of the fatiguing and high-impact nature of the exercise. The reader is advised to read Flanagan and Comyns (2008) for more inforn1ation on the breakdo\vn of each phase. 1 "Focuson !anding mechanicsduring jumps •Quictlandings •Minimal f!e;iion ilt knces& hip.s • "Freezew on ground contact •Anklejumps& skippins • Emphasis on short ground contact-jump height unimportant • Legs like "stlff springs" • ~stay on bal!s of foet" • Fixed jump height "Emphasis on short groundcontact& zome dcgrcc of jump hcight • CT use d as fccdback tool • Hurdlc hcight can be increased when CT is indicativo oi fost SSC • Shortground contact time & maximize jump height • ''Jump fost,jump high" • RSl uscd a5 fccdb;;ck too! • RSI u~cd to optimize dropping hcight & to monitor p!yometric pnformance Fig. 20. 7: Ffanagan and Comyns (2008) four-phase model for developing fast SSC properties. 1357 358 1 FITNESS IN SOCCER FITNESS IN SOCCER Strength training and functional training Strength training and functional training 20.7 SETTING UP GENERAL STRENGTH TRAINING PROGRAMS 20.7.1 Determining the maximum The measuring of 1 RM (repetition ma:ximum) is in1portant for deternüning the nurnber of repetitions. It is the •veight that e<1n be repeated just once. iviake sure the player can perform the exercise \Vith proper technique \Vhen measuring l RlvI. If the player sho\VS ínsufficient training experience, a 3-5 Ri\tl measuring can be used and 1 RM can be "calcuh1ted." Set out belo•v is a description of ho\v the 1 RM value co.n be detern1ined: s VV<1rm up by performing 5-10 repetitions at around 40';~1. o Rest for 1-2 ITlinutes. o Stretch the inuscle group. Carry out 3-5 repetitions at 70~(1. 0 Try the \Yeight you think you \Vill be able to repeat once. "' \.-Vait for 3 1ninutes. Try again \Vith n1ore \Veight if it \vas too easy or less if the \Veight felt like too n1uch. 20. 7 .2 Organizational forms of strength training Equal load and repetition: This forn1 is ideal for getting used to the various exercises. It is also used to realize a specific objective. For exan1ple, the training of speed-strength can be achieved \Vith a constantly high nun1ber of repetitions at low resistance. This organizational form should be used to get the players used to strength training. Example: Three sets of eight repetitions at 70% of 1 RM. Equal load and varying repetition: This forn1 is used to mix speed-strength and explosive strength. The load is set at 60-70%, with the number of repetitions varying behveen 6 and 15. Exmnple: One set of eight repetitions plus one set of 12 repetitions plus one set of eight repetitions at 65 % of 1 RM. Equal repetitions and varying load: The objective of this form is to familiarize the n1uscle with different types of loads. Example: Three sets of ten repetitions at 60, 70, and 80% of 1 RM. High pyramid: This form \Vill improve maximal and explosive strength. The number of repetitions is lo\v, but the load is high. Exmnple: Seven sets: Eight repetitions at 80% of 1 fü\i[, six repetitions at 85S6, four repetitions at 901b, one repetition at 100'.,'b, four repetitions at 90'.,'b, and síx repetítions at 85t,:d. Lovv pyramid: This form is used to train muscle endurance as well as speedstrength. The Ioad is lo\ver, but the number of repetitions is higher. Example: Seven sets: 20 repetitions at 5056 of 1 RM, 15 repetitions at 60~6, ten repetitions at 70;;'b, six repetitions at 80%, ten repetitions at 70'.,'i;, 15 repetitions at 60::~, and 20 repetitions at 50'.,'~. Complex Training: This alternates biomechanically similar high-load weight-training exercise \Vith plyo1netric exercise, set for set, in the sarne 1vorkout (Ebben, 2002). This creates a post-activation potentiation of the n1uscle and allo\VS the use of 1nultiple training types. Exmnplc: Five sets of 3-5 repetitions at sos;1 of 1 RNI follo\ved by five sets of 3-5 counter-move1nent jt1111ps. Rest is nu1ch higher dueto the nnture of co1nplex training. Cluster Training: This con1prises an intra-rep rest of anv\vhere bet\vcen 15-30 seconds. There are generally hvo types of cluster-trJ.i.ning n1ethodology: 1) undulating, \vhere the resistance is increased in il typic<il pyra1nid fashion (Haff et ai., 2003) and 2) ascending, \vhere the n~sistance is increased after each successive repetition. Exm11plc: One to three sets of lüxl repetitions at 85'';, of 1 Ri\1 \Vith 15 seconds rest bet\\'een each rep (i.e., 1 repetition con1pleted 10 titnes \'dth 15 seconds rest bet\veen repetitions). 20.7.3 Effects Single versus multiple sets: The greatest training effect is achieved in the first set of repetitions. Although the follovving sets also generate an additional effect, this is far less than in the first set. If there is not n1uch time available, it can be beneficial to do justa sin~ gle set of each exercise. Frequency (nu1nber of training sessions per \Veek): Recent research shows that hvo or three strength workouts per \Veek are ideal. Further training sessions do not provide for n1uch further improven1ent in performance. Different forms of strength training can be organized, of course, enabling the frequency to be increased. Number of repetitions: Three to five repetitions are best for devolving strength biomotors (Turner, 2009). Intensity: lt is best to keep the intensity of training between 85-lOOrb of 1 RM. This intensity range will generate the greatest effect. 1 359 360 FITNESS IN SOCCER 1 FITNESS IN SOCCER Strength training and functional traíning Strength training and functional training 20.8 GENERAL STRENGTH TRAINING EXERCISES We give a number of examples of general strength training exercises belo\v. Toward the end of this section, we \vill discuss other training modalities (e.g., stability ball, TRX, medicine ball, etc.). ./ Bent-over Row o M11scles: Trapezius, Rhombiods, Latisimus Dorsi, Teres Major, Teres Minar, Deltoid (Posterior), Biceps Brachii o Executíon: Player stands in an athletic stance, bending the torso to an angle of approximately 45 degrees. Keeping the back straight, the player "rows" the bar to his chest \vith an overhand grip. 0 Muscles: Quadriceps, Harnstrings, Glutes o Execution: Stand with feet in a staggered stance. The ideais to then lower the body, keeping your back straight so the back leg is bent.-Continue the descent until the knee is just above the floor and then drive backup. If working with wornen, you should ensure the Q angle is at a minimum. This can also be dane with the rear foot elevated . ../ One-Iegged squat The player positions himself in a similar position to the goblet squat, but in this case, one foot is in the air, placing all the movement on the standing leg. Ensuring the sarne coaching points noted above (i.e., chest up and out, core engaged, weight coming through heel, back straight), we squat down as low as possible before requiring an ascent to finish the movement. Players can in turn perfect this by adding in load or doing it from a bench to get greater depth. Fig. 20.11: One-/egged squat B A Fig. 20.8: A) Start Position of the Bent~Over Row: Back slays ffat, not rounded, so lumbar spine stays strong. B) Finish position: Efbows tuclred in, and bar being pul/ed into chest. v' ../ One-Iegged squat lvith a lateral hop This also uses the sarne starting position as the one-legged squat. The player bends his right knee at an angle of 90° and hops on his left leg lOcrn to the outside and then back to the center. The player then hops laterally and returns to the center. Split Squat Fig. 20.9: Split Squat ../ One-Iegged hopping on the spot This uses the sarne basic position as the one-legged squat. The player hops quickly on his left leg at a rate of three jun1ps per second for 40 seconds. The right foot remains in the sarne position and the hips are fixed. The player ensures that he lands on the mid-foot. The sarne procedure is then repeated with the right leg. Fig. 20. 1O: Rear Foot Elevated Split Squat Fig. 20.12: Shou/der rehabilitation circuit- W, T and Y. 1361 362 FITNESS IN SOCCER 1 FITNESS IN SOCCER Strength training and functional training Strength training and functional training Fig. 20. 13: P/ayer ho/ds a pfank posilion while rolfing the bali out in front of the body, keeping the hips, back and head inline. By rolling the bali away, it p!aces stress on the core. ./ Single-Arm, Single-Leg, Straight-Leg Deadlifts. 0 Muscles: Hamstrings (Semitendinouis, Semimembranouis and Bicep Femoris). Gluteus Maximus, Glutes Medius, Erector Spinea. • Execution: Just put one foot in a TRX set to approximately knee height, so the leg is bent at around 90 degrees. Any higher may be uncomfortable. From there, hinge at the hips and reach the leg in the TRX straight back behind you, making sure to keep a flat back. Fig. 20. 15: Single-Leg, Single-Arm Deadlift. Dumbbef/ is held in the opposite arm to the Jeg. During descent, push the leg in the suspension kit away while maintaining a flat back. Fig. 20. 14: Stir the Pot: The pfayer ho!ds simifar position as above, but this time he ro/ls the bal/ around in a circle using the forearms, p/acing stress on the obliques. 20.9 TRX/SUSPENSION TRAINING. Many clubs now also incorporate suspension training into their strength programming for players, and this adds a great <leal of variety to a program. The advantage of the TRX is that it is compatible with most places (most come with a doar hinge), so even when travelling, strength training can still be completed. It allows you to train the entire body, and you can combine movements for greater complexity (e.g., train in all planes of motion). When using a suspension training system, it is important to remember the following: o Ensure the suspension trainer is used under supervision at all times in order to guarantee correct execution. • It is imperative that the body stays in line (e.g., not breaking at the hips and the back is not hollow). o The head should always be kept in a neutral position. • Vary the angle of the trainer, because the steeper the angle is, the easier the movement will be. Some examples of exercises using the TRX/suspension trainer are highlighted below: ./ Single-Leg Squat (Pistol Squat). • Muscles: Hamstrings (Semitendinouis, Semimembranouis and Bicep Femoris), Gluteus Maximus, Glutes Medius, Quadriceps (Vastus Lateralisal, Vastis meediatialis, Vastus intermediasis & rectus femoris). 0 Execution: Stand on one leg. Slowly lower yourself down-keeping your back flat, chest up and proud, and core engaged. Ensure the weight is moving onto the heel as the descent continues. As you reach the bottom, drive up using the heel and hips (but not the back) to starting position. Fig. 20. 16: Pistol Squat ./ Chest flies 0 Muscles: pectoralis major, deltoideus, triceps brachii, anconeus o Execution: Start off in the position above, but instead of lowering yourself into a press-up position, the arms come out to the side, forcing you to lower down. The movement is similar to a pec fly. Fig. 20. 17: Pec Fly 1 363 364 1 FITNESS IN SOCCER Strength training and functional training 1365 FITNESS IN SOCCER Strength training and functional training ./ Leg Raises 0 o Muscles: Rectus Abdominis, Tensor Fascia Latae, Obliqus externus abdominis, rectus femoris Execution: Holding yourself up \vith elbows soft (not locked out), keep your posture upright, inhale, and bring your knees to your chest. ./ Plank 0 o Fig. 20.21: Medicine baff behind-head throw: The bali is thrown behind the head backwards or up into the air. Once more, ensure that tripie extensions ofthe ankfe, knee and hip are prominent throughout the movement. Fig. 20.23: Chest Press: This can be done simpfy in an athletic position or add a jump before throwing. Again ensure extensions of the ankles, knees and hips. ./ Rotation throws ./ Back Twist Throw Fig. 20.22: Rotation Throws: The bali sits on one side of lhe body. Rota te through so the bafl is thrown against the wall. Fig 20.24: Back Twist Throw: With your back to the wal/, tum and throw the bali side to side. This helps to develop rotational power. Fig. 20.19: Pfank Fig. 20.18: Leg Raises into training to help develop the force-velocity curve. Medicine balls are a great tool in helping to develop explosive power and rotational strength, and they add variation to programs. You can use different weights of medicine balls for repetition ranges, different sizes (e.g., Slam Balls, etc.) and different surfaces to deliver a training stimulus. As a power exercise, the medicine ball is great because it can help with triple extension of the ankle, knee and hip (all required in sprinting mechanics, jumps, etc.). You can also use these in normal training, such as press-ups on a medicine ball. A fet.v uses of medicine ball exercises are highlighted below. ./ Chest press rectus abdominus and erector spinae. Execution: This is an isometric exercise that requires you to hold a position (bridge) between your forearms and toes. Ensure that your hips, back and head stay in line, drawing the abdomen in and contracting the glutes as well. 1 20.1 O MEDICINE BALL The medicine ball can be incorporated ./ Behind-the-head throw Muscles: Transverse Abdominus, ./ Medicine Ball Slam Fig. 20.20: Medicine Balf Sfam: Extend through ankfe, knee and hip, sfamming the ba/f onto the f/oor. 366 FITNESS IN SOCCER Strength training and functiona/ training 1367 1 FITNESS IN SOCCER Strength trainíng and functional training 20.11 FUNCTIONAL STRENGTH TRAINING FOR THE SOCCER PLAYER 20.11.1 lntroduction: What actually is 11 functional"? "Functional" is a very broad term that may mean different things to different peo~ ple. Something that is "functional" for one person may not be for others. The ques~ tion is rather more like whether something is "functional for whom" or "functional for what." What is functional for you is determined by the person responsible for you and your training. Functional training is much more than squatting, pulling, pushing, and using all kinds of "functional" fitness equipment. How many ways are there to squat and lunge? The answer is simple: an infinite number of ways. A squat to lift a box from the floor is different to a squat you do to get something from the bottom of the fridge. Look at how many different squat and }unge positions a soccer player finds himself in during a match or training session. Functional movement is very complex for soccer players because they get into numerous different positions and situations during a match. The aim of functional training is to prevent injuries from occurring in these various situations and eventually also become stronger in these situations. To achieve this, it is important to train movements and not muscles. We want to prevent injuries when a striker shoots hard at the goal or when a defender blocks a shot. Also, we want the goalkeeper to be able to punch away a high cross powerfully and explosively. We can incorporate these specific movements of soccer into our strength training. Does this mean that we cannot lift any heavy weights or that hypertrophy training has to be functional? Of course not. There is nothing wrong with a soccer player with a large muscle mass, nor is there anything wrong with lifting heavier weights. However, when it comes to specific strength training for soccer and wanting to make our players stronger in the various movements on the pitch, we should perhaps apply a somewhat more functional thought process. We want to take advantage of that muscle mass in a positive manner. All exercises can be featured on a functional training continuum, such as the following: Least Functional Most Functional Leg Press - Machine Squat - Barbell Squat - One-Leg Squat Airex Pad - One-Leg squat Least Functional Most Functional Machine Bench Press- Bench press- 08 Bench press- Push-Up- Medicine Bali Chest Pass These are justa few examples of exercises along the continuum, but other examples include hop-dominant, vertical press, horizontal pull, and torso exercises. 20.11.2 Specific strength training I Basic principies of functional training lt is easier to describe the notion of "functional" by introducing and explaining a few basic principies related to functional training. Functional movement patterns are individual and sport specific, yet they are based on a number of universal principies that help to determine our analysis, testing and training. 20.11.2.1 Functional training is Three-dimenslonal We constantly move in three dimensions (simultaneously) during functional activities. The three planes are forwards-backwards (sagittal plane), left-right (frontal plane), and left-right rotations (transverse plane). This means that each joint can move in six different directions, so we absolutely have to take account of this in our training. We very often observe that only the sagittal plane is discussed in strength training. Weight machines, in particular, are frequently limited to movements in this plane, while we find that most injuries occur in the transverse plane through extreme rotations (cruciate ligament injuries are a good example of this). It is important to understand how each muscle and joint moves functionally in the three planes, and we certainly need to train them in these three planes. For example, when the knee finds itself in the valgus position, only the muscles that are activated at the right moment and respond properly can inhibit the movement and prevent the knee from twisting too far and damaging the anterior cruciate ligament. 20.11.2.2 Jntegrated It is also important to understand that any change in one plane has consequences for the other planes. Each influence on a system has consequences for other subsys~ tems. The body is an integrated whole in which bones, muscles, joints, ligaments, proprioceptors and the nervous system work together in order to function. It is not functional to isolate one of these systems and train it separately, even if that were even possible. There is no such thing as proprioceptive training. The proprioceptors are trained all the time, and the nervous system is stimulated constantly. Whether we are lying down, sitting or standing up, we are always giving signals through the proprioceptors. ln our strength training, we can ensure that we stimulate the nervous system in a functional way so the muscles respond in the most appropriate manner. By holding a static position during a "plank," or by consciously driving the knee above the second toe, but not past the toes, we give limited information to the proprioceptors, causing them to perhaps not respond appropriately if our body then unconsciously makes a potentially dangerous movement. 20.11.2.3 Taking account of gravity, mass and ground reaction forces We are constantly subjected to gravity and ground reaction forces. When we stand up straight and take a step forward and run, jump, and so on, there are movements in our muscles and joints that are caused by gravity and other influences that result from ground reaction forces. The front foot will pronate, the knees and hips will bend, the body will stoop forward and bend laterally, and so on. We will therefore not spend any time on the m. tibialis posterior, for example, to create eversion in the foot. For the sarne reason, we will not focus on the hamstrings to bend the knee, nor will we focus on the hip flexors (muscle group) to bend the hip. ln an upright position, rather than these movements being brought about by the muscles, they merely slow down the opposite movements. For example, when we are standing 368 1 FITNESS IN SOCCER Strength training and functional training up, the abdominal muscles do not bend the torso. The body does not have to exert itself to lower the head to the knees \vhen it is upright, because it is done by gravity. For this reason, we train the muscles in a functional way in our coaching (by stretching them) and, as a result, it's clear that there is little point in doing exercises like crunches. Ground reaction forces are everywhere on the soccer pitch, and they are absorbed by the body upon landing from a jump or planting a foot to change direction or decelerate. It is therefore important that athletes are aware of these forces. 20.11.2.4 30 /oad - 30 unload Initially, gravity would appear to impede us in all our movements. It causes a stooped posture when we are older, prevents us from being able to jump high, makes the ball drop faster from a throw-in, and makes us work harder if we want to pick something up. ln biomechanical terms, however, gravity is the greatest ally in all our movements. Without gravity, there would not be any load phase, and we would be unable to unload in the opposite direction. Just try jumping without first bending your knees. We want togo up, but the body first goes down in order to load the muscles before jumping up. Likewise, a goalkeeper will first rotate backwards before throwing the ball. ln most situations the goalkeeper will be running forward and the arm and ball will trail behind him dueto momentum. This will create a lengthening (eccentric load) of the anterior muscle chain and result in an unload (the throw). It is therefore important to consider what gravity does to us in the tlu·ee planes of movement. How does it use the movements to activate the proprioceptors, and how do these activate the muscles so We get the desired chain reaction in the body? They have to be able to provide both mobility and stability in order to absorb or slow down a movement. The energy stored by the muscles during stretching (eccentric loading phase) is then used to create the opposite movement (concentric unloading phase). It is therefore necessary to first analyze the movements made by a soccer player during a match in order to then create a training environment and exercises that include the sarne movements. The stronger and more flexible a soccer player is in the loading phase, the more powerful the unloading phase will be. FITNESS IN SOCCER Strength training and functional training 1369 20.11.2.5 Controlled movements: Conscious intent and unconscious reaction All our movements are influenced by where we are looking, what our hands are doing, or what our intention of movement is. This means that a soccer player consciously kicks a ball toward the goal, but it's his body that decides the way in which to execute the task. We cannot consciously activate muscles and move joints or decide which movement comes from which part of the body. This all occurs subconsciously. This also means the body will take the path of least resistance, so muscles and joints with limited mobility or flexibility will be dra\vn on less, so other joints and muscles have to compensate for this. This can unfortunately lead to overload. Movement occurs subconsciously. Proprioceptors respond subconsciously and activate muscles without us having to think about the process. We could therefore question why we ask our players in a strength training session to keep their knee over their foot during a lunge and not let it extend beyond the toes. We could also question why \ve ask players to consciously tense their abdominal muscles during the plank exercise. The conscious stimulation of muscles and controlled, rigid movements are far removed from what actually happens on the soccer pitch. lt misleads the proprioceptors and prevents or impedes movements that then occur on the pitch. ln every training exercise, particularly in the context of injury protection and strength training, it is important to let these subconscious movements and reactions take place. This way, the body also knows what it needs to do when it is confronted with the sarne movements on the soccer pitch. 20.11.2.6 Kinetic Chain It is unnecessary to explain that the body is a whole. The foot is attached to the ankle, the shinbone, the knee, the hip, and so on up to the head and the arms. If l stand upright with my right hand extended to the left, this influences the entire body. My upper body rotates to the left, as does my pelvis. My right foot will turn inwards and my left foot outwards. All the muscles and joints move in a chain reaction, and this is often referred to as the kinetic chain. ln addition, the most remarkable aspect is how this all occurs subconsciously. For a particular movement on the pitch (e.g., a goal kick taken by the goalkeeper) it is important to know what influence the hands, eyes, and kicking foot have on the rest of the body. This is the only way we can prepare our players in an optimal manner during strength training sessions for all the movements that can occur on the soccer pitch. 20.11.2. 7 Growing Stronger and Reducing injuries It is important that through functional training we are making our muscles stronger and therefore more resilient to injury. The main thing we want as a medical department is zero or minimal non-contact injuries. Many coaches use functional training because it sounds good, but they fail to perfect a move before adding load. This means that if an athlete can't bodyweight squat with the correct technique, it is then worked upon. We don't take a shortcut to correct the imperfection so we can add load, because this will create a problem elsewhere in the kinetic chain. Growing stronger means we can tolerate more load through the body, so the body will be able to handle more sprints, decelerations and changes in direction. It is important that exercise selection is functional based, so instead of using leg-extension machines, we use a split squat. It is also important to note that not all exercises 370 1 FITNESS IN SOCCER Strength training and functional training FITNESS IN SOCCER Strength training and functional training need to be functional to the sport. Olympic lifting movements like the clean, jerk and snatch are explosive movements that will promete a greater rate of force development, teach hip extension, and load the hamstrings eccentrically in the catch positions. Although the exercise movement is not a soccer action, it is functional because of the benefits of the exercise. 20.11.3 Training soccer movements: Specific strength training for soccer players must resemble soccer The basic principies form the guideline and foundation for the creation of exercise programs. We do not want to just haphazardly give the players some exercises to do and then leave them to their fates. This is why it is important to have a certified strength coach and have a11 sessions completed with supervision. When we set up an exercise program, it is equally important to know how players move, both as a player and as a coach, and this is often the only thing we do not leam in relation to strength training. Most information concerning strength training is based on anatomical research carried out on bodies in a laying position. We leam a lot about individual muscles in isolation, but the body only knows about movements made by severa! muscles together. Each time a joint moves, a large number of muscles play an important role. One muscle is stretched, another muscle shortens, and other muscles stabilize, with a11 the muscles 1vorking together. Muscles respond to movement by creating movement themselves, and, as already mentioned, they are subject to various forces that they contrai and stabilize before themselves developing the desired power. A specific movement of a joint in a particular plane of movement can be obtained in five different ways. Although it goes without saying that the form of the joints, as well as the muscles and ligaments, can limitar prevent a particular movement, the principie applies in every joint. An example of this is given below. The extension in the hip created before a player kicks a ball can be obtained by: • leaning the body back without moving the leg • bringing the leg back without moving the body • raising the leg and leaning the body back, but letting the body move faster than the leg • leaning the body forward and bringing the leg back, but letting the leg move faster than the body 0 leaning the body back and also bringing the leg back In soccer, the extension is mostly created by the final method above through the momentum in the run-up to the bali. ln this way, we can analyze each movement in each joint at any moment and then incorporate this into the strength training schedule. The better we can incorporate soccer movements into strength training, the greater the transfer of strength training to the soccer pitch will be. 20.11.4 Stability and mobility For soccer players, it is also paramount to not remain neutral but rather be able to pass through a neutral position in the different planes of movement and contrai these movements subconsciously, therefore being able to respond appropriately via the proprioceptors and the muscles. ln other words, can a player become destabilized in a soccer-specific position or movement and still control it? Also, can the player carry out his movement more quickly, with a greater ROM, ar a heavier load? We will once again use the motor skills of a specific movement to make a player better and stronger. In recent times, the strength training continuum has shifted to a joint-by-joint approach initially put forward by coaches such as Mike Boyle and Gray Cook This approach looks at the body from the ground up and determines which joints need stability ar mobility to maximize performance gains. It is important to add that all joints require both mobility and stability, but they will be at different points on a stability-mobility continuum. Stability is a part of mobility, and the body must be able to move in a mobile and stable way. Stability without mobility is rigidity. This breakdown ultimately helps us understand how many common injuries occur. An example for this would be if the ankle lacks mobility (Range of Motion), there will be implications further up the joint-by-joint approach, normally found in the next joint up, the knee in this example. The Functional Movement Screen (FMS) created by Gray Cook is one example of how mobility or stability issues within the joints might be highlighted. 20.11.5 Transition zones The transition zones are the extreme stretch zones of a movement when transferring from one movement to another. Most movements in soccer have two transition zones. When kicking, there is a transition zone where the kicking leg transfers from the rear-swinging phase to the for\vard-swinging phase. After the ball has been kicked, the leg swings through and is slowed down in the second transition phase. Both zones are equally important, and it is useful to train in both zones in arder to get stronger and avoid injuries. The aim is not to train directly and constantly in one maximal eccentric position, but it is necessary to know how far a player can go and how strong he is in this zone. It is usually in these zones that a player will sustain injuries. The transition zones are individual and sport specific. As coaches, we can set up and adapt strength training programs based on a player's individual potential. 20.11.6 Proprioceptors The proprioceptors have already been mentioned a few times in the preceding section. They are sensory organs located in the muscles, ligaments, joint capsules and so on. They convert physical input and movement information into electrical signals that are sent through the body. This information is transmitted to the spinal column and the brain, although bridging this distance would often take too long for the information to be received by the muscles and allow them to respond. It is highly likely that there is also a direct network between the muscles and the joints in the fascia and the tissues in order for this information to get to the muscles more quickly. There are various proprioceptors: the Pacinian corpuscles, the Golgi-Mazzoni corpuscles, the Ruffini corpuscles, the Golgi ligament endings, free nerve endings and muscle spindles. They all have a different sensitivity, adapting quickly or slowly to a constant stimulus, and they are located in different places in the muscles, joints, joint capsules, ligaments and fascia. This means that the proprioceptors are difficult to see, and although we do not know exactly how they work, it is clear that we have to take them into account. When we talk about movements, muscles and joints, we know that although a proprioceptor gives certain 1371 372 1 FITNESS IN SOCCER Strength training and functional training information, we need all the information from all proprioceptors in arder to have a clear picture of what is happening in the body. It is for the proprioceptors, in particular, that we incorporate functional training and soccer-specific movements into our coaching. The question we ask ourselves is how we can integrate the proprioceptors into our training in an efficient as possible manner. Proprioceptive training is often discussed in the area of rehabilitation or training. This creates a false picture of \vhat the proprioceptors exactly do. Proprioceptors are present everywhere in the body, constantly ernitting signals for movement. We cannot turn them off, and non-proprioceptive training does not exist. We must therefore ensure that we train in a functional way in order to stimulate the proprioceptors in the correct manner. 20.11.7 Practice ./ Analyzing soccer movements Now we have all this information, as \vell as some idea of what functional training means for a soccer player, there perhaps remains the question of how to do this and what exactly to do. For this reason, we will also analyze a soccer-specific movement in this chapter and devise an exercise program for it. The most obvious movement is shooting for goal. FITN ESS 1N SOCCER Strength training and functional training 1373 Set out below is a series of exercises for the different components of the kicking movement: ./ Position before kicking (these exercises create extension, abduction and externai rotation in the kicking leg Fig. 20.25: Forward /unge: Swing lhe arms over lhe fronl leg. We analyze the positions of the banes in the right hip joint during the load phase before kicking and the swing phase after kicking: • Before kicking: flexion, abduction, externai rotation • After kicking: flexion, abduction, internai rotation The movement carried out in the right hip during the kicking motion is: flexion (from a bent position to a more bent position), adduction (from abduction to adduction) and internai rotation (from externally rotated to internally rotated). An additional factor is that all of the movement takes place on one leg. ln our training, we \vill start with what the player in question is most successful at. This could be on hvo legs with the support of the hands, for example, depending on his or her possibilities. Ultimately, we want to do everything possible to get to the stage of single-leg training exercises. Although the above examples are soccer-specific actions, soccer movements are also short, sharp, dynamic movements that should never be forgotten. The hamstrings need to be strong to handle the loads placed on them . ./ Setting up exercises The program for training the preceding movement can consist of three parts. We want to make the player more flexible and stronger in the position prior to kicking, in the position after kicking, and in his movement \vhile kicking. Depending on our objective (e.g., flexibility, mobility, strength, etc.), we can add weights or other training equipment to the exercises. We can also vary each position and movement in the three planes of movement. Depending on the player, we will begin with an easy or more difficult exercise. Fig. 20.26: Fof\vard /unge from a raised position: Swing the arms over the front /eg. Fig. 20.27: Jumping forwards from a one-/egged position: Swing bolh arms over the front feg. 374 FITNESS IN SOCCER 1 f ITN ESS 1N SOCCER Strength training and functional training 1375 Strength training and functional training ./ Position after kicking - kicking Ieg Cl e.,, 'C$·- u til rn " ~ ~-; ~ <ll W,E! Eõ o. ~e e o ~ > .e :e"' TIro ~ o. e Fig. 20.28: Foot on the bench: Swing the arms over the front /eg. ./ Position after kicking- support leg 3' .Q ,., "O o .o 2 o .e ;:: ,., ~> o .o ~ e. TIrn o. rn .e .2 "O :oo. ::J € ~ o o ~ X "'" e o :g e o ~ -~ .e Cl :e ü ro ~ o. " :g€ ;:: _g ~ o u ª" ;e X "' ">~ e. "' ~ Ê e o :g e o ~ Fig. 20.29: Forward lateral /unge: Swing the arms toward lhe rear /eg. 20.11.8 Drawing upa plan The intensity and sequence of matches during a season require thorough planning of ali aspects that are important to a soccer player. Modem-day soccer has become very demanding on the physical capacities of the athletes. Players have to be strong, fast and powerful, yet also able to sustain this for 90 minutes. At the sarne time, a coach also wants his best players to be able to play in all matches by avoiding injuries as much as possible. A player must therefore be as fresh as possible on the day of the match while also being able to train as hard as possible betvveen matches. For this reason, each aspect of strength training also has its place in the plan for the season and the match. It goes without saying that 1.ve will not plan any functional strength training with weights for the days before or after a match. However, we can incorporate injury-prevention exercises ar functional flexibility training into the warm up for a training session ar in a brief strength training session on those days. If we assume that all our exercises are functional, we can then propose the following weekly plan: .e Cl N o. E e o ~ > ~ "E 3' o 5 o~ ro :o ,., E rn ~"O " rn >-o ro- "' e .o" ~ :e 'õ ~.e :Bro e o ~ > t5ro ~ .,,e"' ~ ·;;; õ .!!! "e. ~ .Q :a.,, "'" "" ~ Ê e o :g o .o ">~ "O ::J ~ ~ o u "> ~ e. ,., o. .e .2 e "O :oe. o. e õ ,., .e ;:: _g TIrn "'~ ro E " e e. e. ~ o u e o ,., :g ">~ "O o .o e. :oe. ~ ::J u e. "" ~ Ê o "' ~ Ê e <I ~ o ~ ""'_,, N .Q "" 376 1 FITNESS IN SOCCER Strength training and functional training Preactivation is the dynamic preparation of the muscles for what they will be doing on the pitch. This can be dane in a very functional way, with body weight and with movements that also occur on the pitch. We want to make the proprioceptors and muscles alert with light eccentric movements without causing fatigue or muscle damage. This is dane, in principle, for each training session and match. FITNESS IN SOCCER Strength training and functional training players often train at their limits, and any additional stimulus on the legs can push them over the limit. Although this has to be taken into account, this type of training certainly has its place in the players' weekly training schedule in the context of injury prevention and flexibility. Fig. 20.32: Example: Fonvard /unge extending to lhe ank/es with dumbbel/s and retuming to the shou/der press. Fig. 20.30: Example: Hip extension with variations in lhe different planes of movement. Light springing on the front leg to oblain dynamic stretching in lhe hip region. Pure strength training with additional weight has to be structured very carefully. The upper body can be stimulated almost every day without affecting physical readiness later on the pitch. However, we even try to do upper-body training in an upright position as much as possible and with movements similar to those used on the pitch. Hypertrophy training can also be carried out in a functional way and with transfer to soccer. Finally, core training has also been included in the schedule. The muscles in the hip and abdominal regions are often consciously tightened during these training sessions. We explained earlier that muscles function in a different way, and this is why we will also \vork as dynamically as possible in these training sessions. The "core" is an important link in all the movements made on the pitch, so it is important to train it in these movements. This can also be very functional and upright. The explosive throwing of medicine balls from different positions is a very interesting option here. Fig. 20.33: Example with medicine ball. a Fig. 20.34: Examp!e with a Fig. 20.31: Push-pull movemenl on lhe cable machine. Training rolation in lhe torso/hip region and of lhe upper-body musc/es in a functional position. Full-body training or inclusion of the lower body in strength training requires a very controlled and cautious approach. This also applies to functional flexibility training. Players who have not had any experience of this can suffer from muscle stiffness in the first few training sessions. As coaches, we have to take this into account because it can have a direct impact on pitch training. Professional soccer cab/e machine. 1 377 FITNESS IN SOCCER FITNESS IN SOCCER Strength training and functional training Strength training and functional training This weekly plan is of course only an example, and we do not for a moment claim that this is the best plan for all of the players all of the time. For example, a player may need more focus on prevention because of recurring injuries. In the case of a less athletic or younger player who is not selected so much, greater attention can be paid to full-body training. The content of strength training sessions is different in the preparation stage than it is in the middle of the season, when there is a succession of weekend and mid\veek matches. ln a broader plan (e.g., over four weeks), we can ensure we vary the exercises and alter the intensity and weight lifted. For example, we can spend one week improving the movements needed for jumping and heading, as well as preventive work on ankle injuries and calf flexibility. Then the following week, we can pay more attention to the kicking movement and avoiding injuries in the hip region. We can vary this with repetitions, work-rest ratios, planes of movement, and so on. SUMMARY ln this chapter, the physiology of muscle strength and various strength training programs lvere discussed. Strength training in soccer is now an essential component of the training week and should be incorporated in the weekly training program when possible. Strength training should be periodized into the annual training program in order to enhance performance and to reduce the risk of injuries. Strongerplayers can sprint quicker, jump higher, and change direction more efficiently, and they may also be more resilient to injury than weaker players. Heavy two-legged strength exercises such as the squat can be used to improve maximal strength, while one-legged exercises such as the pistol squat can be performed to improve functional strength. Improving upper body strength can help a player to push opponents off the bali and win aerial duels. Core stability exercises should be performed as often as possible to improve pelvic stability and control in order to reduce the risk of groin and pelvic injuries. REFERENCES Balsom, P.D., Seger, J.Y, Sjedin, B. and Ekblorn, B., 1992. Physiologicil Re5ponoco to M;ixlmal ln1cnsity !ntcrmíltcnt e•Cró8!. European Journal of Applicd Physiology, 65(2), pp.l-1-1-149 Bo.bbcrt, M.F., G_crritscn, K.G., Litjcm;, M.C. and Van So!.'S!, A.J., 1996. Why is countermo\'cment jump height grca!cr than squal jump hc1ght? Med. So. Sports Exerc., 28, pp.1402-1-112. Bobbcrt, M.F and C'15iuo, R.L.J., 2005. ls thc cffcct of a countcrmovement on jump hdsht dic to active statc dcwlopmcnt? Mcd Sci Sports Excrc., 37(3), pp.·1-10-146. Busco, C., lto, A., Komi, P.V., Luhtancn, P., Rahkila, P., Ruoko, H. and Vit=!o, J.T., 1982. Ncuromusrulm funetion 1md mcclunical cfficicncy of hunt.1n !cg extensor musde5 during jumping cxcrósc>s. Aeta. Physiol. Scand., 114(.1), pp.5-H-50. Ca\'agna, G.A and Cil!erio, G.G., 1974. Effcct of strctchlng on lhe elastk cliaractcristics and the contractilc components strialed Muodc. J. Phpiol., 239, pp.l-14. Cronin, J.B., McNair, P.J and Marshall, R.N., 2001. Magnitude and dcci.y of Strctch·lnduced enhanccmcnt of Powcr Output. Eur J Applied Phyr.ioL, 8-1(6), pp.575-581. Deanc, R.5., Chow, J.W., Tillman, M.D. and Foumicr, K.A., 2005. EffoclS of Hip flexor training on sprint, shuttle run, and \'Crlical jump pcrforrnanre. Journal of Strcngth & Conditioning R"5carch, 19(3), pp.615-621. Ebbcn, W.P., 2002. Complcx Training:A llricf Re\'icw. jouma! ofSportsSci and Mcddne, l, pp.42-16. Flanagan, E.P. and ComyM, T.M.., 2003. Thc Use of Contact lime and thc Rcactivc Strcngth !ndcx to Optimiic fost Strctch·Shorlcning Cyde Training. Strcngth & Conditíonins Journal, 30(5), pp.32-38. Ha~, G.C., Hobbs, R.T., Haff, E.E., Sands. W.A., Piercc, K.C. and Stone, M.H., 2()(13. ClustcrTraining: A No\'cl Mclhod for lntroducing Trnming Programmc Variation. Strcngth & Conditioning Joumal, 30(1), pp.67-76. Ho/f, J. Bcrdahl, G.O. and Ilratcn, S., 2001.Jumping hcisht dcvclopment and body wcight considcrations in ski jumping. ln: Muller, E., Sclnvamcdcr, H., Rau:lmcr, C., Lindingcr, S. and Korncxl, E., 2001. Sdenre and Slding. Hamburg: Vcrlag Dr Kovac. Pp.-103-112. Hoff, J., Gr.m, A. and Hei gero d,/., 2002. Maximal Strcngth Training improves acrobiccndurance P"rformancc. Scand j Mcd Sci Spolt!l, 12, pp.288-295. Hill, A.V., 1970. First and Lastcxpcrimcnt5 in musdc mcchanics. Ncw York: Cambridsc Univcroity Pres&. McClymont, D., 2003. Thc use of lhe rcacti•·e strcngth índex as an indica!or of plyomctric traíning conditions. ln: Reil!y, T., Cibri,J. and Arnu'jo, D., cds. Science and Foolbnll V:l11e Prorecdings ofthc Fif!h World Congrc:;s on Sports Sdcnceand FootbnlL Li~bon, Portugal, 11-15 April. Ncw York: Routledgc; 2008. pp.·IOS-116. Morcau, N.G., Simpwn, K.N., Tccfcy, S.A., Damiano, D.L., 2010. Musde archi1ccturc prcdicts maximum strcngth and is rc!atcd to activity !c\'cl5 in cerebral pnlsy. Physica! therapy, 90(11), pp.1619-30. Mycr, G.D., Ford, K.R., Mctcan, S.G. and Hcwetl, T.E., 2006. The Effocl• of P!yomctric \'crsus dynamic ~t<1bilization nnd balance training on lower cdrcmity biomcchanics. Amcrican )ou mal of Sports Medicine, 34(3), pp.445-155. Puavolaincn, L., Hakkincn, K. Hamalancn, J., Nummcla, A. and Ru>ko, H., 1999, Explosivc strcngth training improves Skm running lime by i~pro"ing ninnins cconomy and mu~dc power. J Appl Physiol, 86(5), pp.1527-1533. Pottc1gcr, J.A., Lockwood, R.H., Hnub, M.D., Do lera_~ B.A., A!umzaini, K.S., Schroedcr, J.M. and Zcb110, C.J., 1999. Mutde powcr and fibcr c~1iracteristic foll<;>l~·ing 8 wccks of plyomctrk trnimng. Journal of filrcngth and Conditionins Rc~carch, 13, pp.275-279. Rimmcr, E. and Slm\'crt, G., 2000. Effccts oi a plyomelrk interwntion program on Sprint pcrformance. /ournal ofStrcnsth ;md Condi· tioningJoumal, 14(3), pp.295-301. Spuns, R.W., Murph;~ A.J. and Watsford, M.L., 2003, The Effcct oi Plyomctrk training on dist<1ncc running. Eur J Appl Physiol, S9(1), pp.1-7. Sto.n~, M.H., Sto~e, M.E., Sands, W.A., Picrc~, K.C., Newton, RU., H.11f, G.G. and Carlock, J., 2006. Mmdnmm Strcngth nnd S!rcngth tramms -A rclahonship to cndurance? Strcngth & Conditioning Joumal, 26(3), pp.4·1-53. Turner, A., Owings, M. and 5chwane, J., 2003. lmprovemcnt in ninning economy aftcr 6 w""ks of plyometric trnining. )ou mal of Strcngth and condilioning rc1:<,;1rch, 17(1), pp.60-ó7 Turner, A., 2009. The Sdence and pradice oi Periodization: A Brid Revicw. Strcngth & Conditioning Journal, 33(1), pp.34-16. Wilson, G.J., Wood, G.A. nnd Ellio\I, B.C., 1991. Optlm~l stiffness of ~cries clíliltic componcnt in a otrctch-~hortcn cyde ~Ctl\'i\y. / Appl Physiol, 70, pp.S25-íl33. Wisloff, U., Helgcrud, J. nnd Hoff,J., 1993. Strcnglh and Endurance oi Elite Socrer Playcrn. Medicine and Sdcnce inSport5and Excrcioc, 30(3), pp.462-167. Wislo,ff, ':1·' Dst~gn~, .e.' 1-!clsc.rud, J., Joncs, R. and ~-off, J., 200-I. Slrong Corrdation of Maximal S<iuot Strcngth with Sprint Pcrform~ncc and \crhcnl Jump Hcight m EhtcSotror P!aycrs. Bnhsh Journal ofSports Medicine, 3S, pp.285-283. \'ossen, J.F., Kramcr,J.F., Burkc, D.G. and Vowcn, D.P., 2000. Comparison ofdynamkpush-up troining and plyomctrk push·up tr.lining on uppcr-body powcr and strcngth. Journol of Strcnglh and CondiHoning Rcscarcli, J.1(3), pp.248-253. 1379 FITNESS IN SOCCER lnjury prevention FITNESS IN SOCCER 3SO 1 Strength training and functional training 1 INJURY PREVENTION Jan Van Winckel, Steven Probst, Balder Berckmans, Pieter Jacobs, Mathíeu Gram 21.1 INTRODUCTION Due to the specific physical demands of soccer, the incidence of injuries is significantly higher than in other team sports such as field hockey, volleyball and basketball. The risks of acute injury in professional soccer are threefold greater than in the construction, manufacturing, and service sectors of industry (Drawer and Fuller, 2002). Large-scale epidemiological studies indicate that the injury prevalence rate in professional soccer is approximately 15%. This means that for a squad of 25 players, approximately four players will be unavailable at any given time due to injuries. Hãgglund (2007) reported that 65-95% of players had at least one injury every year. ln a recent study in European professional soccer, Ekstrand et al. (2011) demonstrated that a team with a 25-player squad can expect 15 muscle injuries every season, with muscle injuries accounting for more than a quarter of the total layoff time. Contact injuries are responsible for just over a half of all injuries, and these are often linked to externai factors and therefore not completely avoidable. Non-contact injuries, however, can be largely avoided, and these are divided into acute non-contact injuries and overload injuries. Muscle injuries, such as strains, are generally regarded as the largest group of avoidable injuries. Extensive epidemiological studies by Professor Ekstrand et al. (2011), conducted over a ten-year period with 51 different professional clubs, have shown that muscle injuries account for 35% of the total number of injuries. Up to 80% of these muscle injuries are non-contact injuries that could be avoided to a large extent through individual injury-prevention programs and workload management. This substantial number of muscle injuries is responsible for more than 25% of the overall absence of players from match-play and therefore has a major impact on the success of the team. This is especially significant when considering that muscle injuries alone (in a squad of 25 players at professional levei) are responsible for 223 days of unavailability per season, including 37 match days and 148 training days. Injuries to the hamstring muscle group are the most common injuries, accounting for 37% of all muscle injuries. The average unavailability per muscle injury lasts 14 days before the player can return to squad training. 1381 382 FITNESS IN SOCCER Jnjury prevention 1383 1 FITNESS IN SOCCER lnjury prevention 21.2 CONSEQUENCES OF INJURIES Injuries and the associated unavailability of players have substantial consequences for the players as well as the coach and the club. The development of youth players and the careers of professional players can in some cases be severely interrupted. ln both cases, it can take a long period of rehabilitation before they are able to perform at the top level again. This means the coach cannot field his strongest team, resulting in diminished performance. Poor match performances and results also have economic consequences for the club. Injuries therefore have a greater impact than just the players' physical complaints. ln 2003, for example, Scandinavian researchers conducted a study of more than 300 players in Iceland's two highest professional soccer divisions (Arnason, 2003). The aim of the study was to examine what part individual fitness and proneness to inju1y played in a team's success. The conclusion was that teams with fewer injuries finished the season in a significantly higher place in the league than teams with more injuries. Similar to this, Hãgglund et al. (2013) reported that injuries have a significant influence on performance in the league and European competitions in male professional soccer. The findings stress the importance of injury prevention strategies to increase a team' s chances of success. ln economic terms, the main effect of a large number of injuries is the high cost incurred by the club. The medical costs related to injuries are substantial. Recent research demonstrated that these costs can be reduced through injury-prevention strategies (Verhagen, 2013). Moreover, clubs continue to pay salaries while injured players (the club's assets) cannot perform. Their market value also drops, resulting in the transfer possibilities for such players falling as well. The greatest source of income for most clubs comes from training and guiding players to a higher levei, with the result that they can be sold to other clubs for substantial amounts of money. Given the average wages of players in Europe (e.g., €150,000 per annum in Belgiurn, €250,000 in the Netherlands and €350,000 in England), the average pay for players in the USA ($150,000 per year in MLS), and the high incidence of injuries, it is obvious that even a 5% reduction in the number of injuries would have a huge financial benefit. A recent study sho\ved that 2% of all professional players in the Premier League ended their careers because of injury (Windsor insurance, 1997). This is in stark contrast to another study in \vhich the researchers asked players \vhy they had stopped playing soccer. Of those questioned, 50%) said they had been forced to end their careers prematurely because of injury (Drawer and Fuller, 2011). 21.3 CONCEPTUAL MODEL: INJURY PREVENTION Injury prevention is an organized strategy in \Vhich all sections of the club have to \Vork closely together. ln 1992, van Mechelen and co-workers argued that measures to prevent sports injuries do not stand alone. They presented a model of prevention based on the surveillance of injury, identification of risk factors, and implementation of prevention strategies. Two years later in 1994, Meeuwisse put forth a multifactorial model of causation. This model attempted to account for the interaction of multiple risk factors, both intrinsic (internai) and extrinsic (externai). It sho\vs clearly the importance of identifying intrinsic predisposing factors, as well as recognizing those extrinsic factors that interact to make an athlete susceptible to injury, before an injury-inciting event occurs (Figure 21.1). 1. Estab!i~h!ns the extent of the injmy prob!em: • lndclence · Severltv / 4. kse~$ing its effeçtivenen by repeatiog step 1 2. htabli~hing the aetio!ocv;::nd meehanbm of sports injuries / 3. !ntroducing a preventive mea~ure Fig. 21. 1: Four-step sequence of injury·prevention research (Meeuwisse et ai., 1992). ln 2005, Bahr and Krosshaug designed a conceptual model that elaborated on the characteristics of the inciting event as a component of the causal pathway. This model suggests that an injury is the result of a complex interaction between intrinsic and extrinsic risk factors rather than being exclusively caused by the injury mechanism that is generally associated with the onset of injury. Each player has their o\vn particular set of intrinsic factors or risks. Intrinsic risk factors can be further subdivided into modifiable or non-modifiable factors. Modifiable risk factors can potentially be altered to reduce injury rates through the in1plementation of injury-prevention strategies (Meeu\visse, 1991}. Intrinsic risk factors-such as physicul fitness, technical level, muscle strength and flexibility, and joint mobility-can be n1anipulated by targeted training and physiotherapy sessions. If intrinsic strength improves, the player may be less predisposed to injury. The co1nbination of these individually determined intrinsic risk factors gives the player a certain predisposition to injury. This predisposed player is then exposed to extrinsic risk factors, making him even more susceptible to injury. Examples of extrinsic risk factors include \Veather conditions and the playing surface. For example, a field in poor condition can have a negative influence on the player's intrinsic predisposition, and this makes him n1ore susceptible to injury. A good soccer field, ideal \.veather conditions, anda referee who has the match under control all have favorable influences on the player's predisposition. Although these extrinsic risk factors are outside our professional domain, they do need to be included in order to draw up an accurate profile for each player. 384 1 FITNESS IN SOCCER FITNESS IN SOCCER lnjury prevention 1385 lnjury prevention 21.4 INTRINSIC RISK FACTORS Intrinsic risk factors can be subdivided into modifiable and non-modifiable factors. Although high-risk players are susceptible to injury, they may not have been injured yet. It is the presence of both intrinsic and extrinsic risk factors that renders a player susceptible to injury. The simple presence of these risk factors is, however, insufficient to produce injury. The sum of these risk factors and the interaction between them "prepares" the athlete for an injury to occur in a given situation (Bahr and Krosshaug, 2005). The final link in the chain that actually causes the injury is the inciting event (Meeuwisse, 1992). 21.4.1 Injury Mechanism Extrinsic risk foctors o '"' C~nMr Heltl1t An.1tonty Heohh l'lwsl:.1.1 fitn~;; l'tÓprl<lN!pllon fl~-<ilo~Hy ~!w:ru!Jr bilme<:> Mut.ouL1r 5lrrn5th The chronological age of peak performance varies between sports and depends on the player's attained technical skill, developed power, endurance capacity, and experience. The majority of players are at their most successful after they have reached athletic maturation. Athletes participating in rugby, soccer, volleyball, speed skating, distance running, and cross-country skiing achieve success in their late twenties or early thirties (Bompa, 1999). Injury mechanism lhmMnfact<>U Rd~tt<' o Te.1nun.1tc oOppcruont f'1l\itnnnwnt o Humldity O Temf"'tOt<m> Soc<:erl1dJ o Surfa'~ o Malnl<''""'"" Spc•t•~qull'flWl\l o Oot!w:; o 5h= Proi<-<:lh-ccqulpmrnt o Sh!n &'l<'\rJ; Hdm«t ' Inciting e\'ents til ""'ro Tr~inlns proar;om o Pui<><l!;;.~U"n ""1.l=<)·de g, o Mlcr<><)'1C• o D.>il;·pl= WorJJ:>.:1d n o '"e> ro"'g:. factors 21.4.1.1 Age Risk factors Intrinsic risk foctors Non~modifiable Despite that these factors cannot be altered, coaches have to take them into account in arder to avoid injuries and develop individual programs. This differentiation is referred to as individual periodization. 3. ~frsocyde F~tlzu~ Jcizitmolion Warmup ;;; iil" R~rowry -" ..a. ;;i o. Adolescents are more injury prone than children. Injury rates increase with age through a diverse range of sports (Yde and Nielsen, 1990; Emery, 2003). "' ~ iil" SkillJ"'rforrnou"'" . The research supports age as a significant risk factor for injury (Freckleton and Pizzari, 2013). Several studies have shown clearly that older players are more prone to muscle injury, particularly to the hamstrings (Verrall et al., 2011; Henderson et ai., 2010; Freckleton and Pizzari, 2013). Hãgglund et ai. (2013) demonstrated that older players (above mean age) had an almost twofold increase in the rate of calf injury, but the researchers didn't find any association in other muscle groups. e Intervention strntegies 1. Screening intrinsk risk foctors and training weaknesses 2. Reducing the extrinsic risk foctors 3. Monitoring \\'Orkload & managing fatigue Fig. 21.2: lnjuf'f mechanism (adapted torm Bahr and Krosshaug, 2005). The reason why older players are more susceptible to muscle injury is unclear, but it has been suggested that age-related changes in older athletes, such as increased body weight and a loss of flexibility, may partially explain the increased risk (Gabbe et al., 2006). ln another interesting study by Orchard et al. (2002), increasing age and sporting experience were identified as intrinsic risk factors for groin injury. These results could be partially explained by the fact that the body's collagen tissue changes in nature with progressing age, so it may not be as able to respond to rapid changes of directions or recover from fatigue (Mays et al., 1991; Wang et al., 2003). Moreover, it has been demonstrated that peak hip adductor and abductor torques significantly decrease with advancing age Gohnson et al., 2004). This final link will tell us, within the conceptual model, something about "the moment" when a player will sustain an injury. It is only when a player is actually on the pitch taking part in a h·aining session or match that he can sustain an injury. A very injury-prone (susceptible) player can undergo a training session perfectly well with a good warm up, good training conditions, and a specially adapted training load. An injury is therefore effectively sustained by the interaction behveen intrinsic and extrinsic risk factors during the "inciting event." This can also be altered by applying particular periodization, adapting the training load, or manipulating other underlying mechanisms. Excessively heavy workouts or excessively short intervals between training sessions can be factors in provoking an injury. Each player has, figuratively speaking, his own "Achilles heel," a certain area of the body that is more susceptible to injury. For one player, it might be his right knee, for another, it might be his left hamstring. The vast majority of injuries are sustained in the area of this figura tive" Achilles heel" when the load imposed by the coach is higher than the player's load tolerance. ln a meta-analysis conducted by Fousekis et al. (2013), a trend where younger players were at greater risk of ankle sprain was also apparent to the limit of statistical significance (.05 < P < .10). This was confirmed in a study by McKay et al. (2001) in basketball players. They reported that younger athletes were at an increased risk of sustaining anl<le injuries when compareci with older athletes. :-- , ;>fli/jj/S 386 1 FITNESS IN SOCCER FITNESS IN SOCCER lnjury prevention lnjury prevention 21.4.1.2 Gender It is well documented that female athletes sustain significantly more knee injuries than male athletes, specifically anterior cruciate ligament (ACL) sprains. Female athletes are three times more likely to incur ACL ruptures (Sutton and Bullock, 2012). ln a study of ACL injuries in elite Norwegian handball players, Myklebust et al. (2000) found that women had a fivefold increased risk of sustaining ACLinjuries when compareci with men. This may be dueto female athletes having, genetically speaking, less strength and the knee often being too flexible (hyperlaxity). Additionally, many explanations have been suggested in the literature for why female athletes incur more serious knee injuries than male athletes, including anatomical, hormonal, and neuromuscular factors (Hewitt, 2000). Unique anatomical features of female athletes, such as a larger quadriceps angle (i.e., the Q angle or the angle at which the femur meets the tibia), could possibly cause a larger relative inward rotation of the knee anda greater pull on the knee muscles during physical activity, therefore contributing to more ACL injuries among females. 21.4.1.3 Height Meta-analysis suggested that height did not differ between groups of injured and uninjured players (Freckleton and Pizzari, 2013). 21.4.1.4 Ethnicity Woods et al. (2004) found an association with a significantly increased risk in players of black origin. 21.4.2 Modifiable factors 21.4.2.1 Body fat percentage (overweight) Being overweight causes the body to waste a great <leal of energy on inefficient movement. A body fat percentage under 10% is recommended for a soccer player. An increase in fat percentage produces an exponential increase in the mechanical load, forces that articular, ligamentous, and muscular stluctures must resist. Care should be taken when determining body fat percentages via skinfold measurements, because these involve a margin of error. Skinfold measurements are, however, very useful in practice for measuring a player's development over time. These measurements are quick and practical, making them very useful for large numbers of players. Current trends in body composition research include compartmental assessment using dual-energy x-ray absorptiometry (DEXA). The advantage of DEXA over other laboratory methods is the ability to assess regional, in addition to total body, composition and analyze separate compartments of the body (i.e., fat, soft tissue and bane) (Wagnei; 1999). 21.4.2.2 Weig/1t Freckleton and Pizzari (2013) included seven studies in their meta-analysis. They did not demonstrate a difference in weight between the injured and uninjured groups, although there was a trend toward heavier athletes being more susceptible to hamstring injury. Fousekis et al. (2013) found that players with increased body weight had a significantly higher risk of non-contact ankle sprains. 21.4.1.5 Anatomica/ characteristics 21.4.2.3 Joint position sense Anatomical characteristics, such as increased foot width, have been linked with an increased risk of ankle sprains (Barker et al. 1997; Baumhauer et ai., 1995). Joint position sense has been identified as an intrinsic risk factor for ankle sprains in numerous publications (Willems et ai., 2005; de Noronha et al., 2006; Tropp et al., 1984). Tropp et ai. (2006) investigated postural equilibrium through stabilometry in soccer players. They demonstrated that in players with a history of previous ankle joint injury, no increased postural sway was found. On the other hand, players showing abnormal stabilometric values ran a significantly higher risk of sustaining an ankle injury during the following season \Vhen compareci to players \Vith normal values. Trojian and McKeag (2006) investigated the ability of the single-leg balance (SLB) test, carried out during preseason e'xaminations, to predict an ankle sprain during the autumn sports season. The researchers found a significant association behveen a positive SLB test and future ankle sprains. 21.4.2.4 Hamstring to opposite l1amstring ratio (H:H0P,) The risk of sustaining a hamstring strain-type injury \Vas sho\vn to increase \Vith a lo\vered hamstring to opposite hamstring concentric ratio at 60° / s in an Australian football population (Orchard et al., 1997). 21.4.2.5 MRJ (magnetic resonance imaging) data Research carried out by Verrall et al. (2001) assessed han1string muscle injuries (strains) with MRI to identify risk factors for reinjury. Athletes from three professional Australian Rules football teams tvith an injury volume greater than 21.8 cm3 were 2.3 times more likely to be reinjured. Furthermore, an MRI-measured injury 1387 388 FITNESS IN SOCCER lnjury prevention 1 FITNESS IN SOCCER lnjury prevention transverse size greater than 55% indicated athletes were 2.2 times more likely to be reinjured. 21.4.2.6 Preseason fitness Players failing to maintain their fitness during the off-season, and therefore starting the preseason in poor physical fitness, are more prone to injury during preseason. These players train with other fitter players and consequently suffer from accumulation of fatigue more quickly. These injuries then put them even further behind the other players, leading to a vicious cycle. Leetun et al. (2004) found that decreased leveis of preseason sport-specific training (i.e., less than 18 sessions during preseason) were risk factors for groin strain injury. 21.4.2.7 Flexibi/ity Intuition tells us there is a relationship between increased flexibility and decreased incidence of injury in soccer. ./' Ankle and knee joint laxity The association between ankle laxity and ankle injury is unclear. Several studies, however, have shown a relation between knee laxity and knee injury. Ramesh et al. (2005) found that anterior cruciate ligament injury is more common in those with joint laxity, particularly those with hyperextension of the knee. Myer et al. (2008) confirmed these findings >vhen they found that a positive measure of knee hyperextension increased fivefold the odds of anterior cruciate ligament injury in female athletes. ./ Muscle tightness Poor flexibility has been identified as an intrinsic risk factor for lower extremity muscle injury (Ibrahim et al., 2007; Bradley et al., 2007; Witvrouw et ai., 2003). A meta-analysis by Freckleton and Pizzato (2013) did not find a significant relationship between AI<E (active knee extension) test results and hamstring injury, although the relationship was approaching significance. The PKE (passive knee extension) test was not related to hamstring injuries. Watsford et ai. (2010) demonstrated that mean hamstring musculotendinous stiffness and mean leg stiffness were greater in AFL players who subsequently incurred a hamstring muscle straintype injury. ./ Range of motion (ROM) Reduced hip extension ROM (or reduced hip flexor Iength) is associated with hamstring injury (Gabbe et al., 2006a,). This research showed that for each 1 degree increase on the modified Thomas test (i.e., decreasing hip flexor flexibility), the likelihood of hamstring muscle strain-type injury increased by 15% in players aged 25 or more. Excessive mobility in the joints-such as the ankle, knee and hip-can give rise to an excessive range of movement in the joint, possibly causing injury. Limited mobility (e.g., in the hip or ankle joint) can also increase a player's susceptibility to injury (Fong et al., 2011). Due to the asymmetric Ioad in soccer, the mobility of the joints can be limited by muscle tension on one particular side of the body. This affects the quality of movement, resulting in a need for other structures to compensate. This can in retum result in overload and injury. Similar to this, Fong et al. (2011) found that dorsiflexion ROM restrictions may be associated with a greater risk of ACL injury. 21.4.2.B Prevíous injury One of the most cited intrinsic risk factors for lower extremity muscle injury in soccer is a previous injury (Hãgglund et al., 2006; Engebretsen et al., 2010). Players who experienced a muscle injury in the previous season had increased injury rates of up to three times when compared with previously uninjured players (Hãgglund et al., 2013). Bennell et al. (1998) also found that Australian soccer players with a previous history of hamstring muscle strain-type injuries were 2.1 times more likely to sustain another hamstring injury. Hãgglund and colleagues demonstrated in 2013 that hamstring injury was associated with past calf injury, calf injury with past quadriceps injury, and quadriceps injury with past hamstring injury. The author suggested that altered running biomechanics caused by the first injury might be an influencing factor. Previous injury has also been related to ankle sprains (Kofotolis et ai., 2007) and groin injury (Arnason et ai., 2004). An increased risk of incurring the sarne type of injury in subjects with a history of injury can be due to several reasons. These include inadequate rehabilitation, muscle strength impairment, muscle imbalance, diminished muscle flexibility, the presence of scar tissue, and functional instability (Engstrom, 1998). Several studies identified a premature return to play as an injury risk factor. Ekstrand and Gillquis (1983) found that players who were inadequately rehabilitated, or ;vho returned prematurely to a pre-injury levei of competition, were at increased risk of suffering an identical injury. Finally, a previous injury is a good predictor for identifying a ;veak zone. The fact that a player frequently sustains an injury in the sarne zone shows that the zone in question could be a weak link. Extensive screening can expose the various risk factors. 21.4.2.9 H:Q ratio ln general, the evidence for the isokinetic H:Q ratio being an intrinsic risk factor for hamstring muscle strain-type injuries is scarce and unclear. Although the H:Q ratio has been identified as a risk factor, the speeds (60, 90, 180 degree/ sec) at which significance levels are found are contradictory. Bennell et al. (1998) found H:Q ratios could not predict hamstring muscle strain-type injuries, despite measuring ratios at varying speeds. ln conflict to these findings, Yeung et al. (2009) demonstrated that the likelihood of hamstring muscle strain-type injuries increased wíth a decrease in the concentric H:Q ratio at 180 degree/sec. A ratio of less than 0.6 was found to increase injury risk by 17 times. ln another interesting study by Croisier et al. (2008), an imbalance profile (a player who has a deficit on two or more isokinetic tests) was an effective method of identifying injury-prone players. 1 389 390 FITNESS IN SOCCER 1 FITNESS IN SOCCER lnjury prevention lnjury prevention 21.4.2.10 Quadríceps and hamstring peak torque 21.4.2.14 Limb dominance A meta-analysis (Freckleton et al., 2013) demonstrated that an increase in qua<lriceps peak torque is an intrinsic risk factor for hamstring muscle strain-type injuries. On the other hand, the study did not support hamstring peak torque as a risk factor for hamstring muscle strain-type injuries. Bennell et al. (1998) also studied eccentric hamstring peak torque, but they did not find any significant difference between groups. In soccer, the dominant kicking leg may be at increased risk of injury because it is preferentially used for kicking. Quadriceps and groin injuries were more frequent in the dominant leg, probably because of a greater volume of shooting and passing / crossing actions by the dominant leg, resulting in injury (Hãgglund et al., 2013). Moreover, limb dominance may result in lingering muscle imbalances in soccer players. This could lead to an increased likelihood of injury, and unbalanced strength between the dominant and non-dominant legs has been found in soccer players (Rahnama et ai., 2005). Ekstrand and Gillquist (1983) found that the dominant leg sustained significantly more ankle injuries (92.3%) than the non-dominant leg in male soccer players. This was also reflected in a study of Barker et al. (1997) that found limb dominance to be a risk factor for ankle sprains. No significant differences were detected in the number of hamstring injuries between the dominant and non-dominant legs in various publications (Verrall et al., 2006; Henderson et ai., 2010). 21.4.2.11 Eccentric strength Engebretsen et al. (2010) found that a simple eccentric strength test was unrelated to an increased risk of hamstring muscle strain-type injuries. 21.4.2.12 Bodymassindex The body mass index (BMI), or Quetelet index, is a measure for human body shape based on an individual's mass and height. It is defined as the individual's body mass divided by the square of the individual's height, with the value being universally given in units ofkg/m2. BMI = mass (kg) (height (m))' Gabbe et al. (2006) sho\ved that a BMI of more than 25 was associated with hamstring muscle strain-type injuries. BMI is inaccurate as a measure of body composition in soccer. For example, tall and muscular players may score high BMI levels, incorrectly rating them as being too fat. For example, a player with a BMI of 26 may have a body fat percentage of just 8%. This player then has a very high muscle mass, so a high BMI is not necessarily a problem. However, a high BMI does give rise to a greater mechanical load on the joints. A change of direction can cause a load equal to five times the body weight. Fousel<ls et ai. (2013) found that players with higher BM!s had a significantly higher risk of non-contact ankle sprain. This might be because the ankle joint absorbs the mechanical loads produced through the constant interaction of the player with the ground and their opponents (Ekstrand and Tropp, 1990). This could make the joint susceptible to injuries. Similarly, Tyler et ai. (2006) identified increased weight and BMI as intrinsic risk factors for ankle sprains. Players with a high BMI might also have shorter playing careers than those with a lower BMI due to the mechanical load accumulated during their careers, which can lead to chronic injuries such as osteoarthritis. Even after their careers end, these players often have to contend with the consequences of years of high mechanical Ioads. 21.4.2.13 Functional asymmetry A difference between the left and right side of the body is an indication of asymmetry. This is often sport-specific because of a one-sided load, or it may be the result of an incomplete rehabilitation or a persisting injury. A difference of more than 10-15% represents an increased risk. Correction of muscle imbalances at preseason has been found to decrease the likelihood of hamstring injury in soccer players (Croisier et ai., 2008). 21.4.2.15 Fatigue Fatigue has been identified in the literature as a component in the occurrence of muscle injury (Worrell, 1994; Garrett, 1996), especia11y since muscle injuries occur more frequently to\vard the end of matches (Hawkins et al., 1993). 21.4.2.16 Aerobic fitness Chomiak et ai. (2000) clearly showed that diminished physical fitness is a risk factor for all injuries in a group of male soccer players. Poor aerobic fitness can induce fatigue, leading to a reduction in the protective effects of the musculature on joints. 21.4.2.17 Psycl1ological factors Ivarsson and Johnson (2010) examined psychological factors as predictors of injury. The researchers found that increased injury risk among junior soccer players was predicted by ineffective coping skills, such as worry. Other ineffective coping skills shown in the literature are self-blame, behavioral disengagement and denial (Anshel and Sutarso, 2007; Lane et ai., 2004). Smith et al. (1993) identified a number of physical and psychosocial variables as predictors of injury: levei of participation, type of sport, age, previous injury, pre-injury stress, mood state scales, and self-esteem. Moreover, they found significant post-injury increases for depression and anger, whereas vigor was significantly less after ínjury (Smith et ai., 1993). Williams and Andersen (1998) have proposed interventions for reducing injury risk. They suggest an athlete can decrease the risk of injury by lessening his susceptibility to the effects of different stressors. Recent research by Ivarsson et al. (2013) demonstrated that injury occurrence was signi:ficantly associated with both the initial levei of daily hassle and the change in daily hassle. 1 391 392 FITNESS IN SOCCER lnjury prevention [ FITNESS IN SOCCER lnjury prevention 21.4.3 lnjury prevention and intrinsic risk factors There are two ways of reducing the effects of intrinsic risk factors. The first approach entails measuring these risk factors and setting up a specific program to eliminate deficits or maladaptations. It does need to be considered that working on one isolated risk factor is often not sufficient to avoid injury. Injuries occur through the interaction between different risk factors. Working in an isolated way is therefore less efficient than eliminating the deficiencies and imbalances through functional exercise therapy that targets more than a local area or one single risk factor. Another method at a lower level, which is particularly feasible for youth players, is a general program based on the specific demands of the sport and the typical maladaptation caused by playing soccer. Maladaptation is an adjustment of the body caused by one-sided training. The advantage of this is that players can be given a general program, thus freeing up time to work with the most injury-prone players on an individual basis. An example of maladaptation in soccer players is the relatively weak knee flexors (hamstrings) as opposed to the knee extensors (quadriceps ). A good initiative in this context was introduced by FIFA under the FIFA 11 and FIFA 11+. The intention was to offer 11 simple exercises (10 + fair play) to clubs of all levels and players of all ages. This enables players to work on stability, proprioception, core stability, eccentric hamstring strength, and so on. These exercises are easy to do and require little equipment. Nevertheless, it has evidently proved difficult to implement these exercises in practice. In this regard, the FIFA 11 + anticipated offering a standardized warm up incorporating all these exercises in a dynamic manner. This means that ali coaches can plan this into their training or match warming up on a regular basis without negatively affecting training with the ball. At the top international levei, injury-prevention programs are, of course, set up on the basis of individual player profiles. Based on thorough screening at the start of the season, the individual injury-prone zones are set out together with the most important intrinsic risk factors. After a certain time, the screening is repeated, so it can be objectively evaluated \vhether a player has improvedor not in relation to particular physical parameters. 21.4.4 Screening: lnjury-prevention strategy The importance of preventing injuries in sports is evident when considering the disabling consequences, personal grief and high financial cost caused by these injuries (Dallinga et al., 2012). Ultimately, a screening is set up to identify the risk of injury within an athlete. In order to reduce this risk by means of correcting the weak link, individualized injury-prevention strategies are mandatory. Thinking outside the box, and thus beyond the local injury level, is imperative when formulating an adequate injury-prevention program. This principie is supported by various findings, such as the empirical findings of Dr. Müller-Wohlfahrt, the club doctor at Bayern Munich, which showed the implication of the spine in 90% of muscular problems (Vazei, 2013). The importance of assessing beyond the local injury level is also in accordance with other research (Panayi et al., 2009; Fox et al., 2006; Hoskins et ai., 2005; Woods et a!., 2004). Ekstrand et al. (2011) found four major muscle groups to account for more than 90% of all injuries in soccer, among which the hamstring muscle was the most affected. Taking this into consideration, an appreciation of neuromuscular connections, as well as an overall lumbar-pelvic structural assessment, is recommended as part of the screening to help resolve chronic hamstring problems (Panayi et al., 2009; Woods et al., 2004). A possible clarification is the significant role the biomechanics of the sacroiliac joint and hip, along with lumbar-pelvic stability and alignment, play in hamstring function and thus the injury mechanism (Hoskins et al., 2005; Woods et al., 2004). Many other aspects can be assessed, providing significant injury-prevention information (Dallinga et al., 2012). The selection of tests, however, will depend on multiple variables, such as the specific sports epidemiology, time, and means at hand. In order to implementa successful screening protocol, a frequent and equally timed set of tests should be performed. These should ideally be rated by the sarne person to enhance intra-rater and inter-rater reliability respectively. A frequent testing program enables a baseline to be established. As such, new values can be compared with the purpose of deciding whether an athlete is at risk of injury and requires an additional individualized injury-prevention program. 21.5 EXTRINSIC RISK FACTORS 21.5.1 Away games Hagglund et al. (2013) demonstrated that match play on away grounds was associated with reduced rates of adductor and hamstring injuries. 21.5.2 Effect of changes in the score Ryynanen et al. (2013) exanüned the effect of changes in the score on injury incidence during the 2002, 2006 and 2010 FIFA World Cups. The researchers found an extensive variation in incidence of injury related to changes in the score during matches of international men's soccer. Injury incidence was lowest (54.8/1000 matchhours [mh]) during the initial 0-0 score and highest (81.2/ 1000 mh) when the score was even but goals had been scored. Players in a winning team run a higher risk of suffering an injury than players in a drawing or losing team. 1 393 394 1 FITNESS IN SOCCER lnjury prevention 21.5.3 Effect of PGDJs Ryynãnen et al. (2013) investigated the association between potentially game-disrupting incidents (PGDis)-such as red and yellow cards, goals, and injuries-and the injury incidence in soccer during three FIFA World Cups in 2002, 2006 and 2010. Official match statistics were obtained for all the matches played in the three tournaments. They concluded that the injury incidence was significantly higher during match periods within a minute of, or during a five-minute period following, a yellow or red card, another injury, ora goal (PGDis) than during other match periods. 21.5.4 Synthetic grass and floor surface Some research into the impact of synthetic grass has been funded by its manufacturers. Additionally, the results in current literature are contradictory. For these reasons, it is difficult to evaluate the effects of synthetic grass. What is certain, however, is that the first and second generations of synthetic grass involved a greater risk of injury because of the lack of shock absorption and the larger impact on joints caused by greater surface stiffness. Zanetti et al. (2013) found that in slalom, artificial grounds produced higher horizontal peak accelerations compareci to natural ground. Orchard et al. (2003) proposed playing on artificial turf as one of the primary extrinsic risk factors of ankle sprains. Nowadays, we see more and more synthetic grass pitches in youth academies. Hughes et ai. (2013) found only small differences in the ability to perform certain movements when comparing artificial and natural surfaces, concluding that fatigue and physiological responses to soccer activity do not differ markedly between surface type when using the high-quality pitches of the present study. Nevertheless, players must always take care when they switch from one surface to another. The stiffness of a surface affects impact forces, and this may result in overload to the joints and tendons. Friction is necessary, however, for rapid starting, accelerating, stopping, cutting, and pivoting, all of which are inherent to soccer. This mechanical overload could affect injury incidence. A change of surface creates a different load, and this change in load can partially be responsible for the discomfort experienced among players. Consider this at the start of the season, when the pitches are hard, or during rainy or snowy weather. Ali of these circumstances and conditions create a different load. Players often indicate after training sessions or matches on synthetic pitches that they have problems in the area of the adductors, calves and hamstrings. As always, the body must be given time to adapt to a different type of load. Given the friction that occurs between the shoes and the surface, as well as the fact that synthetic grass allows fewer rotations, the knee joínt and ankle are more susceptible to injury on synthetic grass. Wearing specially adapted foohvear for playing on synthetic grass can reduce this friction. 21.5.5 Weather conditions A temperature of 14-lSºC is ideal for playing soccer. If it is warmer, dehydration can then give rise to muscle injuries. If it is colder, the muscles can cool down, making them more susceptible to injury. Insufficient hydration or a Jack of glycogen affects performance. Only 2% dehydration, possibly caused by hot weather, can give rise to a 20% decrement in performance. FITNESS IN SOCCER 1 lnjury prevention 21.5.6 Injuries caused by opponents (foul play) Ryynãnen et al. (2013) compared the incidence and characteristics of foul play injuries and non-foul injuries. They demonstrated that the number of injuries was associated with the number of fouls in a match. The length of absence resulting from foul play injuries was significantly shorter than that of non-foul injuries. Two mechanisms leading to ankle sprains have been found that are thought to be specific to soccer. 0 Player-to-player contact with impact by an opponent on the medial aspect of the leg, just before or at foot strike, resulting in a laterally directed force causing the player to land with the ankle in a vulnerable, inverted position. ° Forced plantar flexion where the injured player hits the opponent's foot when attempting to shoot or clear the ball (Andersen et al., 2004). It is said that 18-31% of all match injuries stem from fouls during a match. Depending on the study, 76-100% of these injuries are caused by opponents. Astrid Junge indicated in one of her studies that almost all players were prepared to commit a professional foul if they felt it was necessary. The majority of them said this was all part of the game. 21.5.7 Protective equipment Shin guards are compulsory during matches. However, shin guards are not wom in training sessions at all clubs. Nevertheless, this preventive measure can help reduce the number of contact injuries (contusions). 21.5.8 Appropriate footwear When changing shoe brand, type or size, the feet will need time to adapt. Traditionally, the old shoes are replaced at the end of the season. Preseason is then started with new shoes on hard ground and a higher number of training sessions. This results in players with foot problems and injuries every year. It is often suggested that the man-shoe-surface interaction is a major problem in soccer injuries, but until now, there is little evidence that using different commercially available soccer shoes can influence the risk of injury. ln this regard, Gehring et al. (2007) compared soccer shoes with round and bladed studs. No significant differences in externally applied knee joint loads during a complex injury-related movement were found. The significant increased activation of quadriceps femoris with round studs during the criticai weight acceptance can be associated with an additional internai load on the anterior cruciate ligament. The researchers conclude that there is no higher risk of suffering non-contact knee joint injuries with bladed soccer shoes. Galbusera et al. (2013) found that studded and bladed cleats did not significantly differ in their interaction with the playing surface. 21.5.9 Ankle bracing and taping There is a general consensus in the literature that ankle taping or bracing decreases the Jikelihood of ankle injury (Sitler et ai., 1994; Tropp et ai., 1985). Engstrom (1998) suggests that the use of anlde braces could possibly increase the kinesthetic awareness of the ankle and increase support to the joint by limiting hind foot motion, specifically inversion. ln recent years, scientific authors have highlighted the importance of combining proprioception and stability exercises together with preventive taping or bracing. 395 396 1 FITNESS IN SOCCER lnjury prevention 21.5.10 Preseason Hãgglund et al. (2013) reported that quadriceps injuries were more frequent during preseason, whereas adductor, hamstring, and calf injury rates increased during the competitive season. ln a study by Stevenson et al. (2000), the incidence of injury was related to the time of season. ln a study of recreational sports (Australian football, field hockey, basketball, and netball), the researchers found that injury incidence to the lower extremity was highest in the first four weeks of the season. There are two possible reasons for this. Firstly, preseason is typically the time when physical fitness needs to be rebuilt. Therefore, the workload imposed during these first few weeks is higher than during the season. Players "\Vith poor physical fitness are especially susceptible to injury. Another cause of this increased incidence of injuries is the detrained state of some players. Even with a normal load, these players will sustain injuries more easily. ln the mid-season break (off-season), it is therefore important for players to maintain their aerobic fitness and avoid detraining. On the other hand, it is important in preseason to measure aerobic fitness and then optimize and adjust/individualize the training program accordingly. 21.5.11 End of lhe season A series of interesting shtdies by Tim Gabbett have shown that it is easier to sustain an injury in the second half of the season when compared with the sarne load at the start of the season. lt is not entirely clear why this occurs. It could be dueto (neural) fatigue ora lack of concentration after a long season. 21.5.12 Skill level Numerous studies have investigated the association behveen skill level and the likelihood of injury. The results are contradictory, however, and need further investigation. Petterson et al. (2000) shtdied the association between skill level and injury in male soccer players. They demonstrated that young players \vith low skill levels had twice the incidence of all injuries as a group when compared to more skilled players. 21.5.13 Posilion on lhe field ln soccer, goalkeepers sustain significantly fe\ver injuries than outfield players, but they are more prone to upper-limb injuries, particularly shoulder injuries (Woods et al., 2004). FITNESS IN SOCCER lnjury prevention 1397 21.6 GENERAL INJURY PREVENTION FOR SOCCER PLAYERS Every soccer player has, at some time, been sidelined for a short or long period because of injury. It is an intrinsic element of contact sports that players have to miss matches because of injuries caused by tackles and other contact. The coach can never completely avoid this sihtation. On the other hand, many non-contact and avoidable injuries also occur. These injuries are caused when players with particular intrinsic risk factors are lined up in training sessions and/ or matches. Firstly, more attention has to be paid to the real cause of injuries, especially where recurring injuries are concerned. ln the chapter on functional training, it "\Vas mentioned that the body works like a chain and that any difference in mobility betvveen joints or muscles has an influence elsewhere in the chain. For this reason, injury-prevention programs may be general, but they first need to be adapted to the player in question. The second point that needs attention in the prevention of injuries is training in the transition zones. These are also described in the chapter on functional strength training. These are the zones where most of the muscle injuries occur. The muscles are stretched to the maximum, with rapid transitions from eccentric to concentric contractions. The more flexible and stronger the muscles are, the less chance there is of trauma being caused during eccentric movements. Injury-prevention exercises should be part of the daily training program, either incorporated into the warm up for pitch training or during a specific session in the fitness room. Injuries to four major muscle groups of the lower extremity-adductors, hamstrings, quadriceps, and calf muscles-account for more than 90% of all muscle injuries in professional soccer (Ekstrand et aL, 2011). Hamstring and groin muscle strain-type injuries are common in sports that involve sprinting, acceleration, deceleration, rapid changes in direction, and jumping (Drezner, 2003; Estvvanik et al., 1990; Orchardetal., 1997; Smodlaka, 1980). Hamstring injuries are also recorded as the most common of all injuries, resulting in an average of four missed games per injury (Hawkins et al., 2001). To establish prevention programs, it is important to identify risk factors associated with the occurrence of injury, preferably using analysis accounting for the multifactorial causes of injury (Meeuwisse, 1994). We will focus now on the most important injuries-namely hamstring, quadriceps, calf and groin strains, and ankle sprains-since these injuries account for the majority of all injuries in soccer. 21.6.1 Hamslrings The hamstrings are a bi-articular muscle group, consisting of the semitendinosus, semimembranosus and biceps femoris muscles. Classic anatomy teaches us that the principal functions of the hamstrings are hip extension and knee flexion. ln soccer and for movement in general, they are primarily called on for restraining hip flexion and knee extension, like in the swinging out phase when kicking and/ or sprinting, often from an extended position. Muscles cannot, relatively speaking, produce much from an extended position. This is often the case in soccer, however, resulting in muscles such as the hamstrings being susceptible to injury. Depending on the type of activity, a trauma can occur in the area of the biceps femoris (resulting from a cyclical exercise, such as a max sprint) or the semí-membranosus muscle (resulting from strain or hyperextension, such as when kicking). 398 1 FITNESS IN SOCCER Jnjury prevention The gluteus maximus is the most important muscle group for restraining hip flexion and the primary extensor of the hip. These actions are used in numerous rnovements in soccer, such as taking off to jump, a powerful change of direction, and restraining a kicking movement. Because of their location and attachn1ent, these muscles are called on in virtually every movement as a stabilizer. Powerful, well-developed glutei are the basis for a strong athlete. If this muscle group is 11.;eakened or does not respond to movement in time, other muscle groups-such as the hamstrings, tvhich are mobilizers-compensate for this, and this can lead to overload and injury. It is therefore important to train both the gluteus group and the hamstrings eccentrically (eventually in a lengthened position) and in synergy, so they are better able to cope with this load. 21.6.2 Adductors Hamstring and adductor problems are among the most common injuries in soccer players. Adductor injuries often occur because of the load around the hip joint being high during a match, such as when a player shoots for goal or changes direction at high speed, as well as \vhen playing on slippery ground when the adductors are constantly adjusting in order to find stability. The adductors are subjected to a repetitive high load due to the asymmetric movements in soccer and the typical kicking motion. Good core stability and correct strength ratios betvveen the different muscles of the lower limbs and eccentric tendon training will reduce the risk of injury. 21.6.3 Pelvic girdle The pelvis is the central point of the body \Vhere a large number of muscles have their origin or points of attachment. The pelvic girdle is involved in just about every movement in soccer. A soccer player therefore sustains many injuries in this region. The risk of injuries is reduced if the muscles are well developed in this region. We often see injuries in soccer players in the form of pubalgia, overloading of the adductors or hip flexors, or tendonitis of the abdominal muscles. We also often see injuries in the area of the lower central abdominal muscles and/ or at the common attachment point for the adductors. These can be caused by an imbalance between the upward and oblique strength of the abdominal muscles (on the pubis) and the downward and lateral pulling force of the adductors (on the pubis inferior). Pain in this region can also result from biomechanical or articular imbalances in the rest of the body, causing more stress to be exerted on this region and making these muscles work harder than expected. Examples of this include differences in leg length and differences in mobility between the right and left ankle. The performing of extreme abductions can also lead to chronic microtrauma and cause pain. The lateral (internai and externai) abdominal muscles and the transversus abdominis ensure stabilization of the torso when running, as well as helping to create the strength needed for kicking, throw-ins and heading. They are therefore of great importance. Isokinetic tests show that when compared with the back muscles, the abdominal muscles are weaker (ratio of 70%) in most soccer players than the expected average (ratio of 75%). ln addition, it is not sufficient to train the abdominal muscles with concentric movements, such as classic crunches. ln fact, research has shown the integration of FITNESS IN SOCCER lnjury prevention 1399 core exercises to elicit greater muscle activation of, among others, the abdominal muscles than isolated exercises such as crunches (Gottschall et al., 2013). Flexion of the hip when upright or moving is generated automatically by gravity, with the body playing more of an active role in restraining this movement. Soccer players have to be stable when moving, and they have to be able to return to a stable position after being thro\vn off balance. The core muscles and the pelvic region are essential in this regard. Training these muscles with dynamic core stability exercises and unconscious movements will make the soccer player better in this regard. Given the asymmetric characteristics of soccer, the rotation component is of huge importance. This must therefore be anticipated. Soccer players also need to frequently deal with overload injuries and hypertonia of the hip flexors. It is once again important to know that these muscles are mainly activated in arder to produce concentric movements (e.g., when kicking the ball, taking throw-ins, heading and running). The sarne principies also apply here: Train as much as possible in an upright, dynamic and functional manner. In addition, it is important to keep in mind that tightness of the posterior pelvic muscle chain is possibly restraining the concentric movement of the hip flexors. 21.6.4 Joint sense Cruciate ligament injuries with or without contact with an opponent are also responsible for a large portion of player unavailability. A major risk factor in this regard is the instability of the knee that can be induced through proximal instability or ankle instability. The mechanism behind most cruciate ligament injuries is often the torsion or tvvisting of the knee \vhen landing after a heading duel or \vhen changing direction. Joint sense provides the soccer player \Vith information about his own body, such as where, andin whatstate, various parts of the body are. Italso indicates fatigue or alertness of the connective tissue, such as the muscles and ligaments. As previously stated, the proprioceptors are called on constantly when a player is in motion. Any form of training is proprioceptive training. Functional injury-prevention exercises help to train the proprioceptors with regard to activating the necessary muscles quickly and correctly in arder to contrai a particular movement or return from an unstable position. This trains unconscious reactions and increases body awareness. All of the above helps to prevent injuries. Exercises can be made more challenging and more difficult by, for example, working on unstable surfaces, closing the eyes, or distracting a player by throwing him a ball. Hübscher and Refshauge (2013) published a review on the effectiveness of neuromuscular training for the prevention of sports injuries in athletes. Their pooled analyses revealed that multi-intervention exercises (comprising balance and agility training, stretching, plyometrics, running exercises, cutting and landing technique, and strength training) significantly reduced the relative risk of lower-limb injuries, acute knee injuries, and ank.le sprain injuries. /!; Touch & Raise o - StiJrliooPruil.km: Star.doncnefoct -Aclkm: Full name- Birth year Toutll the ground with ywr lunds, rat>etl'w?m uph-ij!h and lift 'j{)Ur oth!>r kMe -En&ngPosilion: ~~ lmporUmt: ".., V> V> "'1-leg starn:ewith arms and rontrall!ercl koee rniSed "' -z §" V> Fk!x tlm kr~ of tl'w? star.dir.g !eg a ~ttle bit REPS: lOxeach leg 1. 2. 3. 4. 5. 6. - ~ .::!. =i Prom~ "·o o () ~ elbowtouth () m - SlartiooPosilion: "' HandandfootstaJ1(e """""' Tootll tlle elbowwitlltt..2 llomolalernl kn!!'e -End!hg Positkm: Harnlar.d 1-!oot stance pruillon 11;itll the other leg lx!ndedL'jl frc-nl touch!r;g theelbcw lmoortant: Keep tl'w? b3tk- buttocks-leg ln one fim. ar.d do not louchllm ground,,.,ith thelxmOOd leg. Toperformwitllallfghspeed. REPS: lOxl!ach knee up front Superman Oyrlãmic lun;e - stcrthgPruitioo: -Stcrliooi'Dsilkm: standononefoot Handandfoot5tar.ce -Actioo; -Adioo: U!t ooe arrnand lhe oppo:;ite leg frorn theground -EndfnqPosil.km: Toucll the groumlwitllywr lla.-.6, ralsethem upW_zh and ~fl \'Ollí otherknee "" -End!hg PruiUoo: Dlafionat l·h:mdarul 1-foot starn.:eposlHonwitll theother llpp!'rand lower limb$Mled hwizor.tal lmoortant: Oooot rota te tlv.! Mps and tnml< whenfoc'>iri;g contactwith lhe grcur.d 1-~5tancewittiarrnsarulC<Jr,tralatercilmeernt>ed lmportant: Fli!~ llm ~ cf füe standlng lega !ittle bi1 REPS: 10)teach d13Gona! Prone Butterfly REPS: lOxeach leg Oynamit:Side bridge -5/crfinql'tJ$ítioo: :,:ae Drl(ll1:e forearm prultlonwitlltlle fitet on top of eacllothel -5tllt1.im!Pruilion: Prcne posltlon witll tt-.earms aklng lhe l:o&f and lhe ~gs la&ether lf.tedfrorn -Atlion: thegrouml Ufltlle hl;:-s up as l'\!gll as posslb'.e tobecorr~ a >lraigllt Hnew>111 lhe bod"f -Action: -Endioo Pmitirn: Spr~adtM legs andbrlr.g tt.earms Flll!y (O',>;<r}l!xtend?d5ide brk!ge ..fndinqPosil.ion: lmoortant: Prooe posltlon Witllthe arm; together abave lhe h<!ad and lhe legs op!!n and Mtedfrom thegrouod lrnporta11t: Oooot lookup. Klillplhelegs ~·fted. Keep one straisr.t tne withlegs- buttod:s - b;ick,. avo!d l!ip fuxioo upwards uptoabcve lhe he3d REPS:lOx REPS: 10xead1 :1ide V-Squatting -StcrtiooPasilkm: Open otar.ce witll toes pcintinr. outside -Aclkm: Full name- Birth year Clapthe lur.ds bellind tlle b;ick, sit dm1m as d!2ep as possihk~ wi!llout ~fting heels from t!N! gioundand tooch lhe ground at the line of lhe fl(>e!s. )'Ol-'f - EmJiooP05itioo: Ma,;irmilsquattedpcsfllon lmtJOTl.ool: IIBeplhe kmm> pcintlng m lhe same directionas til-!! foot. REPS:lSx 1. 2. 3. Supine abduction 4. -StottiooPosilicn: SUpme witll the legs crossed anti liftedfrom the groond -Attkvi: Spreadlhe !egs op!!n as wideas prusib!e 5. Suplne with the ~ll.S lifted frnm lhe ground ar.d rnoximJI spread. Ho!dtll!; 6. pcsltKITTfor3". oextenSIDn U/Ult;".'t; - flldjoo eruITToo; lmportmit: Uft the shou!ders a little bit from lhe ground and 1ook up REPS: lOx Supine knee ltfting Quadruped Hip extenslon -Slarti:iaPositkm: Handar.d knee star.ce, botll nipar.d kr~e jci/11: ln S<t f'.e~fon, wltlla fbt back -Aclirm: ~~ =e-:. a;:= m ,.,_ """'= Uftooe !egs:k;wlyup wh!!ekeep:ng tlle<JO'ber.d ai tt.ek~, up to fu!I h!p extimsKm -Aclkm: -Endinq Positioo: -fm!ioo Position: Hand and 1-lmee stancewi!llthe atfü:-r !i'g bernkd ln ti;p extensiO!l Stlpir.e witlll legill S-O'withthefootjustabo'>'e theground& theotherleg hiledllj'.l toS-0' ln b-Otllhip and!meê jcir.ts lffiJlortant: u~ lhe shou,'ders a little bit lmportmit: Do not rotate the hipar tnmk ª ... m "" """' ~;g ~~ e!º IJft alternately 1 krn::-e above lhe ti;ps (slow tempo) ~ ~= E;~ -StartinoPositioo: .supmewitllllm k&:.esbendedin SO' andbotll feeta titt~bit IJledfrorn tlle ground .â:~ Supine plirik-IC61ifting 1-ltigSquat -StrzrtiooPositioo: - Stcrtinq Positicn· Standooonefoot supme p!arlk Mtll lhe shoulders and heel.s oo tlle groond, theb-Jttocks lifted from the ground and the anm cre>sed cwerlhe trunl: -Adion: B1md down the knee toa maxõmurn where lhe 5upportmg foct stiU CJn IR! kept flatonthegrooru.l ::; REPS:lOxeach !eg REPS: lOxeach leg -Aclioo: e "' " V> ~z Raf:leam! bend altemritel'(ooe leg with fui!'( hp flexloo -Endinq/lo$1tkm: -EmJimi Pmitkm: " V> ;§ o 1-leg rnJxklul bemkd staoce Witll the ctber leg L'jl fmrn tlm ground S\!pine p!ank wi1h 1 leg benck">d uJM·ards witll the !mee & hip ln SO' tmportant: Keep the knei'! pol11!íng ffl the sarne d<ri;ctlon as thefoot. oo not letthe kn~ buckt.:i lr1wards. rmvortant: Kl*pthe buttrn:ks m;ixlrnaliyliftedfrom theground g. ~ REPS: lOxeat:h leg REPS: lOxeach leg ~ () ~ "' ..../!; 402 FITNESS IN SOCCER /njury prevention 1403 1 FITNESS IN SOCCER lnjury prevention 21.7 INJURY-PREVENTION PROGRAMS Targeted, efficient injury prevention involves finding a balance behveen a player's load tolerance and the load imposed on the player. Injuries can be reduced by increasing a player's load tolerance and individualizing the traíning load to the needs of the player. The player's load tolerance can be divided into general load tolerance and local load tolerance. General load tolerance comprises a player's general physical fitness, determined from a variety of physical abilities. Basic fitness also includes the quantity and quality of sleep, as well as other psychosocial factors, such as stress, personal situation and fatigue. The general load tolerance can be increased by influencing these factors. Local load tolerance relates to specific zones of the body. This local load tolerance is built up from the interaction between the different intrinsic risk factors per zone. It is a fact that one isolated intrinsic risk factor can be compensated for by other factors that have an influence on that particular zone. Intrinsic risk factors and imbalances can be eliminated via targeted, individual injury-prevention programs. The scientific literature includes (limited) evidence of preventive programs that have an effect on intrinsic risk factors. The influence of most interventions is on ankle and knee stability, as well as hamstring and adductor strength. The second complementary "vay of avoiding injuries is to individualize and manage the load imposed on players. This can be done by adapting the training workload to the individual and applying recovery strategies behveen training sessions and matches. Workload should be individualized within the periodization model. The coach has to create fatigue to allow the body to adapt to the higher training load (overload). During the sarne ~microcycle, the coach has to ensure the players are given adequate recovery in order to produce an optimum level of performance. To achieve this, the accumulated fatigue of the training week has to be reduced by applying the right recovery strategies. The recovery time is different for each player. Some players recover from a training stimulus quickly, while others recover very slowly. Factors that influence this recovery include age of the player, and aerobic fitness status .. Fig. 21.3: A player's injury risk profife based on an injury-prevention screening of the intrinsic risk factors. Body zones at risk are high/ighted (Screenshot TopSportsLab). FITNESS IN SOCCER lnjury prevention 1405 FITNESS IN SOCCER 4041 lnjury prevention 21.7.1 Effectiveness of injury~prevention programs Laursen et al. (2013) investigated the effectiveness of exercise interventions to prevent sporting injuries. Their meta-analysis analyzed 25 trials, including 26,610 participants with 3,464 injuries. The study showed no beneficial effects of stretching, whereas studies •vith multiple exposures, proprioception training. and strength training showed a tendency toward an increasing effect. Strength training reduced sports injuries to less than a third, and overuse injuries \Vere almost halved. They concluded that both acute injuries and overuse injuries could be reduced through the use of injury-prevention programs. Their findings were also confirmed by Owen et al. (2013), who examined the effectiveness of a structured injury-prevention program on the number of muscle injuries and the total number of injuries within elite professional soccer. The study was conducted over two consecutive seasons, of which the first (2008-2009) was the intervention season and the second (2009-2010) was the control season. The training program was performed twice weekly for the entirety of the season (58 prevention sessions). Significantly fewer muscle injuries were observed in this study during the intervention season. The researchers concluded that a multicomponent injury-prevention training program may be appropriate for reducing the number of muscle injuries during a season, but it may not be adequate to reduce all other injuries. 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J Sports Sd, 31{7), pp.i67·7B. e•" 1407 TESTIMONIALS "ln the fo11r years 1ve 1vorked together at Club, I got to know Jan to be a true professional, perhaps the best in Belgiunz in lzis field"- Luc Devroe, former Technical Director at Club BruggeKV. ''As instructor at lhe Belgian UEFA-Pro license course, Jan 1nade an ilnpression by translating difficult theoretical fitness-training concepts into plain footballing language and practical exercise 1naterial. Tllis enabled our UEFA-Pro course participants to acquire the ability to get tlzeir players physically ready to detiver top-levei football perfonnances" - Bob Browaeys, Director of the Federal Trainers' School. "Due to, and thanks to, Jan's vision, expertise and professionalisnz, the teanz stood out tlzrough its fa11tastic general fitness and extre1nely low injury rate." - Adrie Koster, ex-coach of Ajax Amsterdam and Club Brugge KV "Duríng his períod as plzysical coach at Club Brugge, Jan Van Winckel proved t/Iat lzis solid scientific approach leads to strong results. He also gave our club's training approach a ne1v dimension, supported 11ot by intuition but rather on the basís of physiologícal and bio111ec11a11ícal criteria." - Dr. M. D'Hooghe, Honorary Chairman of Club Brugge and Chairman of the FIFA Medical Committee "Due to, and tlwnks to, Jan's visioll, expertise and professionalisnz, the tea111 stood 011t through its fantastic general fitness and extrenzely low injury rate." - Adrie Koster, ex-coach of Ajax Amsterdam and Club Brugge I<V "l ltave seldo111 seen a coach 1vho can translate scie11ce into practical football application so well." - Aad de Mos, ex-coach of (among others) Ajax Amsterdam, PSV Eindhoven, Werder Bremen, RSC Anderlecht "fall is one of tlle best in his field, probably one of the best in the zvorld." - Carl Hoefkens, former player of the Belgian national team, West Bromwich Albion and Stoke City "Jan's 1vork is characterized by professionalism, precision and the systemic use ofmodenz training principies. His scientific work has had a direct i111pact 011 the success of the club in recent years." - Prof. Ahmed El-Shafee, general manager of Al-Ahli Saudi Football Club