TOPIC 9 - Fatigue

Question 1

9.1.1 Define fatigue in sports

Answer 1

A reversible, exercise-induced decline in performance

Question 2

9.1.2. Outline the different types of fatigue

Answer 2

Peripheral Fatigue
- Develops rapidly and is caused by reduced muscle cell force

Mechanisms operating within the muscle that affect the ability of the muscle itself to produce force

Central Fatigue
- Develops during prolonged exercise and is caused by impaired function of the central nervous system

Mechanisms operating outside the muscle that inhibit muscle activation and reduce force production

Question 3

9.1.3. Distinguish between high intensity and endurance activities

Answer 3

High intensity exercise
- Vigorous bouts of intense activity
- Less than 1 sec or up to 1-2min
- Anaerobic

Endurance activities
- Prolonged sessions of low-intensity activity
- Several minutes to several hours
- Aerobic

Question 4

9.1.4. Discuss causes of fatigue in different types of activity or exercise

High intensity Vs endurance

Answer 4

Development of peripheral fatigue in high-intensity activities:
- depletion of energy sources (ATP & CP)
- Increased levels of biproducts (H+ & lactate)

Development of peripheral fatigue in endurance activities:
- depletion of muscle and liver glycogen reserves
- reduction in Ca2+ release
- depletion of acetylcholine
- dehydration, electrolyte loss, overheating

Question 5

9.1.5. Discuss recovery from fatigue after sports

Answer 5

• Different aspects of recovery can occur at different rates
• Recovery rate depend on the type of activity (high-intensity, team sports or endurance)

Question 6

Excess post-exercise oxygen consumption (EPOC)

Answer 6

Fast replenishment:
- Restoration of muscle phosphagens (ATP & CP)
- Takes up to 3 min for full restoration
- Uses 2–3 litres of oxygen

Slow replenishment
- Removal of lactic acid
- Takes up to an hour
- Uses 5–6 litres of oxygen

Question 7

Describe the possible causes of fatigue during exercise bouts lasting 15-30s and 2-4 hours.

Answer 7

• Exercise bouts at 15-30 seconds will usually lead to peripheral fatigue if it is anaerobic and at high intensity –> Depletion of energy stores of ATP and CP
• Central fatigue may be the result of exercising in aerobic, prolonged bouts of 2-4 hours due to impaired function of the CNS
• Peripheral fatigue may occur during bouts of exercise 2-4 hours long due to depletion of muscle and liver glycogen stores, reduction in Ca2+ release, depletion of acetylcholine, dehydration, overheating and electrolyte loss