Muscle types

Athletes start the 100m sprint

Cardiac muscle is unique to the heart. It never tires.

The body's involuntary muscles work our internal organs. They are outside our control.

Voluntary muscles make the body move. They are attached to the skeleton and can be controlled.

Voluntary muscles have fast twitch and slow twitch fibres. Fast twitch fibres contract quickly, but do not use oxygen well and tire quickly. Slow twitch fibres contract slowly, but use oxygen well and keep going for a long time. Top sprinters have more 'fast twitch' fibres. Endurance athletes tend to have more 'slow twitch' fibres.