FATIGUE AND RECOVERY
KEY KNOWLEDGE AND SKILLS
 Key Knowledge
 • the multi-factorial mechanisms (including fuel depletion, metabolic
by -products and thermoregulation)
 associated with muscular fatigue as a result of varied exercise
intensities and durations
 • passive and active recover y methods to assist in returning the body
to pre-exercise levels.
Key Skills
 explain the role the energy systems play in enabling activities to occur
as well as their contribution to active and passive recover y
 explain the multi-factorial mechanisms associated with fatigue during
physical activity and spor ting events resulting from the use of the three
energy systems under var ying conditions
 compare and contrast suitable recover y strategies used to counteract
fatigue and promote optimal per formance levels.
UNDERSTANDING FATIGUE
 Fatigue - Physical and or mental lethargy or exhaustion
triggered by stress, exercise, overwork, illness or disease.
Fatigue is caused by many factors = multifactorial
Robert Malpeli - Balwyn High School 2010
FATIGUE
 Fatigue can be
 Local – in muscles
 General – Whole body
 Chronic – Long term
 Peripheral – at muscles
 Central – Central nervous system
FACTORS AFFECTING FATIGUE
 The causal mechanisms which af fect muscular fatigue are
 Type, duration and intensity of the exercise being performed ,
 Fibre-type composition of the involved muscle or muscles
 The fitness and training status of the athlete
 The nutritional state of the athlete
 The mental state of the athlete.
Myth Busters : Lactic Acid = “Good Guy”
•Lactic acid is continuously being produced and removed –
even at rest
•When glycogen is broken down pyruvate is formed, and
broken down when plenty of oxygen is available
•With low oxygen levels / supply, pyruvate becomes lactate
and hydrogen ions (H+)
•Lactate and hydrogen ions (H+) enter muscle tissue and are
then transported to the blood stream and “shuttled” to other
muscles and cells where this exists in lower concentrations
where the lactate is broken down to produce more energy /
ATP or converted into glycogen to again be used as a fuel
source.
Robert Malpeli - Balwyn High School 2010
CAUSAL MECHANISMS
Fuel Depletion - ATP & PC
•ATP is an immediate energy source but very limited (2 seconds supply)
•PC occurs in limited supply at the muscles (10-12 seconds supply)
These are quick to supply ATP but just as quickly depleted then muscle glycogen and liver glycogen is used in larger
amounts.
Robert Malpeli - Balwyn High School 2010
Fuel Depletion – Glycogen & Fats
•Muscle glycogen is used first during aerobic activities and then liver glycogen
•Once liver glycogen runs low, muscles increasingly use FFA and then stored fats
•The rate of ATP resynthesis decreases quickly (50 – 100% slower) once the body
switches to fats as the main fuel source – this causes slowed performances
•Proteins are called upon when fat stores run low and this leads to an ever greater
slowing down
Robert Malpeli - Balwyn High School 2010
CARBS AND FATS
Ms Ahearn finish an half ironman in 6 hours and 5 minutes
a) Describe Ms Ahearns relationship of carbohydrates and fats as an energy
source over 6 hours of continuous exercise.
b) What effect would this have on performance and why?
HITTING THE WALL
 https://www.youtube.com/watch?v=LKf1eTzmK14
SPACE RACE
 M.socrative.com
 Roomnumber = mrsaunders
Metabolic by-products
•H+ ions – increased muscle acidity which slows the actions of glycolytic
enzymes and the rate of glycogen breakdown
(usually associated with _________________ system dominance)
•Inorganic phosphate - reduces the contraction force of muscles and slows
the release of calcium ions
(usually associated with _________________ system dominance)
•ADP – accumulates during explosive activities and reduces the power
muscles can exert
(usually associated with _________________ system dominance)
Robert Malpeli - Balwyn High School 2010
Elevated Body Temperature
•Normal core temperature = 36.5 – 37.5 degrees celcius (optimal)
•80-90% of body heat comes from muscles contracting
•Heat loss from the body occurs mainly by evaporation/sweating. This becomes
less effective in hot (temps above 36 deg celcius) and humid environments
•Evaporative cooling caused by sweat is assisted by blood being shunted towards
the skin’s surface – this takes with it important fuels & oxygen and reduces waste
removal rate
•Decreased plasma volumes resulting from increased sweating cause increased
heart rate to maintain adequate blood supply to working muscles
Robert Malpeli - Balwyn High School 2010
THERMOREGULATION
 11 degrees is the perfect temperature to exercise at. Anything
above and below this causes to body to fatigue quicker.
SUMMARY
 List for yourself
 Factors af fecting peripheral fatigue
 The causal mechanisms
 Do test your understanding page 122 Questions 1-11
CENTRAL FATIGUE MECHANISMS
 Fatigue at the neuromuscular junction
 The nerve impulses sent from the brain can sometimes be prevented
from reaching the the muscle fibre.
 This is mainly caused by a reduction in acetycholine which relays the
nerve impulse across the synaptic cleft between the motor neuron
and the muscle membrane.
 Central nervous system fatigue
 The CNS can be a cause of fatigue.
 What are some forms of motivation we often use to overcome this?
 The stress of exercise often leads to a conscious decision to
terminate the activity rather than tolerate further pain. Indeed,
research has generally found that the perceived discomfort of
fatigue precedes the onset of physiological fatigue in all but the
most highly motivated athletes. E.g gut running in AFL
IMPAIRED MUSCLE EXCITABILIT Y
 When we are fatigue it becomes harder to convert our
electrical impulses from the brain to muscular contraction.
Have you ever thought you want to run faster but you just
can’t do it?
 The accumulation of hydrogen ions, inorganic phosphate and
ADP are involved in this as well as pottasium
 Pottasium can also af fect the functioning of our muscles.
DEHYDRATION
 When our body sweats we lose a mixture of water and
electrolytes.
 Sweating can create a lower level of blood plasma volume which
affects blood flow to working muscles.
 Also can cause a lack of blood flow to the skin for dissipating
heat which can cause an even bigger rise in body temp.
 Factors
 Duration of session
 Environmental conditions
 Athletes acclimatization
 2% decrease in body weight through fluid loss = 20% reduction in
performance
 3-5% decrease can result in severe performance decrement
along with impaired reaction time, concentration, decision
making and mental abilities
 15% decrease = dead
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Predominant cause of fatigue
100-metre sprint (9.78 seconds)
800-mere run (1 minute, 48.45 seconds)
Marathon (2 hours, 5 minutes, 46.32 seconds)
•Oxygen Deficit – occurs when oxygen supply lags behind oxygen demands –
typically at the start of exercise and when exercise intensities rapidly increase mainly anaerobic energy systems
•Steady State – occurs when oxygen supply meets oxygen demand – largely
aerobic energy system
•Oxygen Debt = EPOC (Excess Post – exercise Oxygen Consumption) – occurs
during recovery whilst oxygen levels remain above resting levels – largely aerobic
energy system
Robert Malpeli - Balwyn High School 2010
EPOC – It’s sometimes good to extend this via an active recovery
Robert Malpeli - Balwyn High School 2010
RECOVERY
WHAT SHOULD A RECOVERY INCLUDE?
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A cool down or active recovery immediately post exercise.
Passive rest
Replenishment of energy stores. PC, glycogen in the muscle.
Replenishment of fluids
COOL-DOWN OR ACTIVE RECOVERY
 Research has shown that a cool -down or active recovery is an
ef ficient first step in enabling the body to recover from
exercise.
 Allows for
 Increased oxygen consumption
 Increased blood flow
 Muscle Pump helps move blood from veins
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Prevents
Venous pooling
Allows for quicker removal of waste products
Prevents muscle soreness
What should an active recovery include?
When should we use it?
PASSIVE RECOVERY
 Good when increased blood flow is not necessary
 Good for restoring PC stores
WHERE DO WE USE EACH
 Passive recovery
 Energy systems  Events -
 Active recovery –
 Energy systems  Events and example of active recovery -
Restoring Fuels - PC
•PC is restored as soon as a passive recovery starts
•PC comes from amino acids (liver) or dietary creatine (red meats, fish or
supplements)
•PC is rapidly restored during first couple of minutes of EPOC/oxygen debt
Robert Malpeli - Balwyn High School 2010
Restoring Fuels – Glycogen
•Glycogen can be “restored” during exercise and athletes often consume
hypertonic sports drinks to lessen glycogen being drained from the liver
(during moderate exercise 1 gram glucose is drained per minute)
•High GI foods should be consumed within first 30 – 60 mins of recovery to
ensure rapid and complete restoration within 24 hrs. Delayed intake will delay
restoration.
Robert
- Balwyn High School 2010
NB – Carbohydrates not stored
at Malpeli
the muscles/liver
will be converted to fat
Removal of Metabolic By-products
H+ ions – removed quickest during an active recovery (same activity @reduced intensity)
Why?
•Oxygen levels remain above resting levels for longer and this assists breakdown
•A “muscle pump” is created when muscles squeeze blood vessels and more oxygen is
supplied to working muscles and wastes removed at a quicker rate. Promotes shunting to areas
of lower concentration
•Promotes venous flow and prevents venous pooling
•Massage and contrast bathing also promote blood flow and speed up H+ removal fro muscles
•Inorganic Phosphate (Pi) is also removed quickest when high levels of oxygen are present and
benefits from an active recovery Robert Malpeli - Balwyn High School 2010
Sodium, Potassium & other Electrolytes
•The movement on sodium and potassium is crucial to the transmission
of messages to and from muscles.
•Sodium, potassium, calcium and chloride are electrolytes critical
to ATP resynthesis
•Electrolyte or sports drinks and excellent for quick electrolyte
replacement and counteracting fatigue
Robert Malpeli - Balwyn High School 2010
PROTEIN INTAKE
 Protein and carbohydrates make for perfect partners in post
exercise nutrition.
 They promote glucose delivery to depleted muscle cells
Counteracting Dehydration and Elevated Body Temperature
•Ice baths / cool pools when off the field/court or at end of activity –
(body temperature can cool down 25 times faster when immersed in cold water)
•Cool/cold showers (when off the field/court or at end of activity)
•Ice vests (during breaks in play, interchange situations)
•Refrigerated cool rooms (during long breaks in play when players taken from the field)
•Ventilation / fans (on side of playing venue)
•Protective shade (either natural – trees, surrounding buildings, etc.. or via shade sails or umbrellas)
•Reduced / modified clothing (to avoid overheating it’s recommended that loose fitting, light weight
and light colored clothing is worn)
Robert Malpeli - Balwyn High School 2010
YOUR TURN!
 Find 2 sports that you play/have played and list some
nutritional strategies for recovery.
 http://www.ausport.gov.au/ais/nutrition/factsheets/sports/