From strength to strength From strength to strength The muscle that can pull with the greatest force is the soleus, just under the calf muscle. This is the muscle that stops us from falling backwards when we stand. Draft only ©Pearson Education: Jules Selmes Learning objectives At the end of the lessons, you will be able to: • understand that continuous or rapidly repeated contraction of muscle results in fatigue • explain that different types of muscle fibre have a significant effect on sporting ability Learning objectives • state that muscle size is related to muscle strength • work accurately and safely, individually and with others, when collecting first-hand data • interpret data relating to the effects of exercise on the human body. Background science The amount of force a muscle can produce is related to its size — the larger the muscle the greater the force that it can produce. ©PCN Photography Background science The role of muscles In many sports, muscles are not required to produce a lot of force but need to be able to contract and relax for prolonged periods of time. Large muscles are not needed in these types of sports. Background science Muscle fibres Muscles are made up of muscle fibres. There are two types of muscle fibre: fast-twitch muscle fibres and slow-twitch muscle fibres. Background science Fast-twitch muscles Slow-twitch muscles power events e.g. javelin endurance events e.g. crosscountry skiing fast contraction speed slow contraction speed high force production low force production low capillary density high capillary density low mitochondrial density high mitochondrial density fatigues quickly slow to fatigue little myoglobin rich in myoglobin Background science Percentage of muscle fibres You cannot change the percentage of muscle fibres that you are born with. Which fibre type do you think you have a greater percentage of in your muscles? Give a reason for your answer. Sprinters have higher percentages of fast-twitch muscle fibres compared to marathon runners. Background science How do muscles help these people perform at their best? ©Alamy Images: ITAR-TASS Photo Agency ©Shutterstock.com: EcoPrint ©Getty Images: Jed Jacobsohn Background science Yoga increases flexibility and strengthens muscles. The muscles do not produce movement, they contract isometrically. Muscle contraction can also be concentric or eccentric. Concentric muscle contraction — the muscle shortens whilst contracting. ©Pete Saloutos Eccentric muscle contraction — the muscle lengthens whilst contracting. Explaining the results Muscle size and performance • The larger a muscle the more force it can produce so it won’t tire as quickly. • For endurance activities muscles need to work for long periods of time but usually without a lot of force so muscles tend to be smaller. Explaining the results Why are lower body muscles stronger than upper body muscles? • We use our lower body muscles more in everyday activities. • Upper body muscles are usually only stressed during specific activities or sports. • Taller people tend to have: • longer legs which make test exercises (press-ups) harder • a greater volume of muscle • longer arms (further away from ground). Explaining the results Why are some people better at power events compared to endurance events? A person with a greater percentage of: • fast-twitch muscle fibres is more suited to power and speed activities such as the vertical jump test. • slow-twitch muscle fibres is more suited to endurance activities. Students who participate in sports that need both power and endurance may perform well in both type of activities. Explaining the results Why does fatiguing one set of muscles not affect the performance of another set of muscles? • A muscle becomes fatigued due to: • the build up of waste products e.g. lactic acid • the depletion of energy sources (glycogen). These effects are localised to the working muscles so do not affect the performance of different sets of muscles. Your results Can you do more press-ups than squats in one minute? Is this true for everyone? Upload your results for the number of press-ups and squats you performed in Experiment B to the In the Zone ‘Live Data Zone’ and see how you compare to other students across the UK. Visit www.getinthezone.org.uk/livedatazone. Your results How do muscles affect sporting performance? Use data from the ‘Live Data Zone’ to help you answer the questions below. 1 Describe the trends in the national data for upper body strength compared to lower body strength. 2 Suggest why some people have greater upper body strength compared to others. 3 What activities and sports are upper body strength important for? Your results How do muscles affect sporting performance? Discuss how muscles impact upon sporting performance. Use your results from the muscle size, power and endurance tests and muscle fatigue experiments. Improving performance Sports physiotherapists such as Ian Gatt carry out strength tests, like those you have performed, on the injured athletes they work with. They select exercises to strengthen selected muscles to help with rehabilitation. ©Ian Gatt Ian Gatt, sports physiotherapist, English Institute of Sport When antagonistic muscle pairs are not equally balanced in strength this can lead to injury. Improving performance Building muscle Researchers no longer recommend using weights close to the maximum that can be lifted to increase muscle size. ©PCN Photography They have found that new muscle protein generation is greatest when using weights at 30% of the maximum an athlete can lift, until they become exhausted. Improving performance Resistance training By understanding muscles, sportspeople can develop more successful training programmes. For example, resistance training stimulates muscle growth by breaking muscle fibres which then grow bigger and stronger. ©Science Photo Library Ltd: Eye of Science Research has indicated that this ability to generate more muscle tissue remains even after periods of inactivity. Improving performance Dancers train their slow-twitch muscles during circuit laps, doing exercises like those you have done, to increase their stamina and endurance. ©Wayne McGregor Random Dance: Ravi Deepres Odette Hughes, Associate Director of Wayne McGregor | Random Dance Improving performance The brain is thought to play a major role in muscle fatigue. Therefore the question can be asked, does endurance training actually train the brain as well as muscle tissue? ©F.C.G Improving performance Rehearsing mentally Psychologists help athletes to mentally rehearse a skill or activity by imagining it in their head. This process has been shown to stimulate the appropriate muscles and help the athlete to prepare for sporting performance. Simon Drane, sports psychologist, English Institute of Sport In the Zone From strength to strength is the Ages 14–16 component of the In the Zone schools experiments. In the Zone is the Wellcome Trust’s major UK initiative inspired by the 2012 Olympic and Paralympic Games. It has been awarded the London 2012 Inspire Mark and is part of Get Set +, the official London 2012 education programme. For more information about In the Zone, the ‘Live Data Zone’ and downloadable teacher resources go to: www.getinthezone.org.uk. In the Zone resources are, unless otherwise stated, licensed under a Creative Commons Attribution-NonCommerical-ShareAlike 3.0 UK:England And Wales License. This means that, unless indicated that restrictions apply, you can copy, share and adapt materials as much as you like, as long as it is not for commercial use. Credits In the Zone is commissioned by the Wellcome Trust and delivered by a consortium led by Pearson Education and Guardian Professional Pearson Education Consortium Teacher and student materials produced by Pearson Education Ltd Illustrations by Oxford Designers and Illustrators Author Jennifer Stafford-Brown, Chief Examiner and Senior Standards Verifier Photo Shoot School – Farringdon Community College, Farringdon, Oxfordshire Advisors and Contributors to In the Zone Ages 14-16 PowerPoint presentation Simon Drane, English Institute of Sport Ian Gatt, English Institute of Sport Odette Hughes, Wayne McGregor | Random Dance Picture credits The publisher would like to thank the following for their kind permission to reproduce their photographs: (Key: b-bottom; c-centre; l-left; r-right; t-top) Alamy Images: ITAR-TASS Photo Agency 10b, PCN Photography 5, 20; Ian Gatt: 19; Getty Images: Jed Jacobsohn 10r; Pearson Education Ltd: Jules Selmes 2; Science Photo Library Ltd: Eye of Science 21; Shutterstock.com: EcoPrint 10l, F.C.G 23, Pete Saloutos 11; Wayne McGregor Random Dance: Ravi Deepres 22; Additional images by Clark Wiseman / Studio8 Every effort has been made to trace the copyright holders and we apologise in advance for any unintentional omissions. We would be pleased to insert the appropriate acknowledgement in any subsequent edition of this publication. Where material is owned by a third party, e.g. some photographs, certain restrictions may apply that you have to comply with. In particular, where a copyright line is included on a photograph you must not modify, adapt, or remove that photo from its context. Thanks to BBC Learning ‘Class Clips’ which feature in the Notes for Slide 6. The website links to 3rd party material, which are used in this presentation, were correct and up-to-date at the time of publication. It is essential for teachers to preview each weblink before using it in class so as to ensure that the URL is still accurate, relevant and appropriate.