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WAPhysical EducationQuick questions
Unit 3: Factors Affecting Performance
Quick questions on Muscle fibre types: WACE Physical Education Studies Unit 3
3short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is slow twitch fibres (type I)?Show answer
Slow twitch fibres contract relatively slowly and generate low to moderate force, but they are highly resistant to fatigue. They are rich in mitochondria, myoglobin and capillaries, giving them a red appearance and a large aerobic capacity. They use the aerobic energy system, breaking down fats and carbohydrate with oxygen to resupply ATP over long periods. A marathon runner or a road cyclist relies heavily on slow twitch fibres because the event demands sustained, low to moderate force output for a long time.
What is fast twitch fibres (type II)?Show answer
Fast twitch fibres contract quickly and produce high force, but they fatigue rapidly. They have fewer mitochondria and less myoglobin, appearing whiter, and they depend mostly on the anaerobic systems for energy. Within type II there are two important sub types.
What are comparing the fibres?Show answer
A clean comparison runs across four traits. Contraction speed: slow for type I, fast for type II. Force produced: low for type I, high for type II, highest in IIx. Fatigue resistance: high for type I, moderate for IIa, low for IIx.
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