What causes fatigue, and how does the body recover and repay its oxygen debt after exercise?
Fatigue and recovery: the types and causes of fatigue, excess post-exercise oxygen consumption (EPOC) and its fast and slow components, and recovery strategies and their physiological basis.
A focused answer to Eduqas A-Level PE on fatigue and recovery: the types and causes of fatigue (fuel depletion, lactate and hydrogen ions, thermoregulation), excess post-exercise oxygen consumption and its fast and slow components, and recovery strategies such as cool-down, refuelling, cryotherapy and massage.
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What this dot point is asking
Eduqas wants you to describe the types and causes of fatigue, explain EPOC and its fast and slow components, and describe recovery strategies with their physiological basis.
Types and causes of fatigue
EPOC and its components
This is why breathing and heart rate stay high after exercise: the body is "paying back" the oxygen and restoring its energy stores. A trained athlete clears EPOC faster, so they recover sooner between efforts.
Recovery strategies
A good recovery plan targets the specific causes of fatigue.
- Active cool-down: light aerobic work keeps the muscle pump working, maintaining venous return and blood flow so lactate is flushed and converted back to fuel, and reducing blood pooling and dizziness.
- Refuelling and rehydration: carbohydrate within the glycogen window (the first hour or two) restores glycogen, and protein aids muscle repair; fluid and electrolytes replace sweat losses and restore plasma volume.
- Cryotherapy (ice baths): cold causes vasoconstriction then vasodilation on rewarming, reducing inflammation, swelling and delayed-onset muscle soreness.
- Massage and compression garments: aid venous return and circulation, reducing soreness and speeding the removal of waste products.
- Sleep and rest: allow tissue repair and restoration of the nervous system, the foundation of recovery.
Delayed-onset muscle soreness
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 20194 marksDefine EPOC and explain the role of its fast component in recovery after a sprint.Show worked answer →
A Component 1 recovery question. One mark for the definition, three for the fast component.
EPOC (excess post-exercise oxygen consumption) is the volume of oxygen consumed after exercise that is above resting levels, used to restore the body to its pre-exercise state (it replaces the older term oxygen debt). The fast component (the alactacid component) is the first, rapid phase, taking about 2 to 3 minutes, and uses the elevated oxygen to resynthesise ATP and phosphocreatine in the muscle and to re-saturate myoglobin and haemoglobin with oxygen. After a sprint, this is why breathing stays heavy for a few minutes: the body is restoring the ATP-PC stores used in the effort.
A common dropped mark is describing only the slow component; the fast component restores ATP, PC and oxygen stores.
Eduqas 20216 marksA games player finishes a match feeling exhausted. Explain three causes of their fatigue, and describe two recovery strategies with a physiological reason for each.Show worked answer →
A Component 1 applied question. Markers reward three causes and two justified strategies.
Award marks for causes: depletion of muscle glycogen, the main fuel, so the aerobic and glycolytic systems can no longer resynthesise ATP fast enough; accumulation of lactate and hydrogen ions () lowering muscle pH (acidosis), which inhibits enzymes and the contractile proteins; and a rise in core temperature with dehydration from sweating, which causes cardiovascular drift and central (neural) fatigue. Recovery strategies: an active cool-down (light aerobic work) keeps the muscle pump working, maintaining venous return and blood flow to flush lactate and speed its conversion back to fuel; refuelling with carbohydrate within the glycogen window restores glycogen stores, and protein aids muscle repair. Other valid strategies include rehydration, cryotherapy (ice baths) to reduce inflammation and soreness, massage and compression garments to aid circulation.
A top answer links each strategy to the cause it addresses (cool-down clears lactate, refuelling restores glycogen).
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Sources & how we know this
- Eduqas A Level Physical Education Specification — Eduqas (2016)