During a half-marathon (21.1km), many runners experience varying types of fatigue at different stages of the race. Explain the causes of fatigue in the aerobic energy system and how these impact performance. (6 marks)
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- Glycogen depletion gradually affects the aerobic system during a half-marathon race.
- After 60-90 minutes of running, muscle glycogen stores become partly used up, which forces the body to rely more on fat for fuel.
- This causes problems as fat needs more oxygen to produce ATP than carbohydrate does.
- Therefore, runners must slow their pace as energy becomes harder to produce efficiently.
- Dehydration also impacts the aerobic system by reducing the body’s ability to deliver oxygen to muscles.
- Sweating during the race decreases blood volume, which means less oxygen reaches working muscles.
- As a result, the aerobic system cannot work as well despite the runner’s fitness level.
- Rising body temperature further affects performance because heat makes it harder for muscles to produce energy.
- This leads to decreased efficiency even when oxygen is available.
- Mental tiredness develops separately from physical fatigue, causing runners to feel the effort is harder than it actually is.
- Consequently, motivation drops and perceived effort increases during the race.
- All these factors combine, making runners progressively slower as the race continues despite trying to maintain pace.
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Sample Answer
- Glycogen depletion gradually affects the aerobic system during a half-marathon race.
- After 60-90 minutes of running, muscle glycogen stores become partly used up, which forces the body to rely more on fat for fuel.
- This causes problems as fat needs more oxygen to produce ATP than carbohydrate does.
- Therefore, runners must slow their pace as energy becomes harder to produce efficiently.
- Dehydration also impacts the aerobic system by reducing the body’s ability to deliver oxygen to muscles.
- Sweating during the race decreases blood volume, which means less oxygen reaches working muscles.
- As a result, the aerobic system cannot work as well despite the runner’s fitness level.
- Rising body temperature further affects performance because heat makes it harder for muscles to produce energy.
- This leads to decreased efficiency even when oxygen is available.
- Mental tiredness develops separately from physical fatigue, causing runners to feel the effort is harder than it actually is.
- Consequently, motivation drops and perceived effort increases during the race.
- All these factors combine, making runners progressively slower as the race continues despite trying to maintain pace.