- Created by: daisy yemm
- Created on: 22-02-19 11:53
Slow twitch muscle fibres
- They contract slowly and can work for a long period of time without getting tired. This makes them good for endurance activities, e.g long distance running and maintaining posture.
- High proportions of slow twitch muscle fibres are found in the muscles you use for posture, such as the muscles in your back and calves.
- Energy is released slowly by aerobic respiration in slow twitch muscle fibres.
- They have lots of mitochondria and blood vessels to supply the muscles with oxygen.
- The mitochondria are mainly found near the edge of muscle fibres, so that there's a short diffusion pathway for oxygen from the blood vessels to the mitochondria.
- Slow twitch muscle fibres are also rich in myoglobin, so they appear reddish.
1 of 2
Fast twitch muscle fibres
- They contract very quickly but also get tired quickly.
- This makes them good for short bursts of speed and power, e.g sprinting and eye movement.
- High proportions of fast twitch muscle fibres are found in muscles you use for fast movement such as the legs, arms and eyes
- Energy is releases quickly through anaerobic respiration using glycogen in fast twitch muscle fibres. They also have stores of PCr so that energy can be generated very quickly when needed.
- Fast twitch muscle fibres have few mitochondria and blood vessels. They don't have much myoglobin either, so they can't store much oxygen - this gives them more of a whitish colour.
2 of 2