Compare the basic characteristics of fast and slow twitch muscle fibres. (4 marks)
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Sample Answer
Similarities
- Both fibre types exist in all skeletal muscles and contract through the sliding action of actin and myosin filaments.
Differences
- Contraction speed differs: Fast-twitch fibres contract quickly for explosive movements, whereas slow-twitch fibres contract slowly for sustained activities.
- Energy systems vary: Fast-twitch fibres rely on anaerobic metabolism, while slow-twitch fibres use aerobic metabolism efficiently.
- Structural differences exist: Fast-twitch fibres are larger with fewer mitochondria, in contrast to slow-twitch fibres which are smaller with abundant mitochondria.
- Fatigue resistance contrasts: Fast-twitch fibres fatigue rapidly, however slow-twitch fibres resist fatigue during prolonged exercise.