Skeletal muscle fibres are classified into three types. They are:
1. Slow – oxidative fibres
2. Fast – oxidative fibres
3. Fast – glycolytic fibres
1. Slow – oxidative fibres have low rates of myosin ATP hydrolysis but have the ability to make large amounts of ATP. These fibres are used for prolonged, regular activity such as long distance swimming. Long – distance runners have a high proportion of these fibres in their leg muscles.
2. Fast – oxidative fibres have high myosin ATPase activity and can make large amounts of ATP. They are particularly suited for rapid actions.
3. Fast – glycolytic fibres have myosin ATPase activity but cannot make as much ATP as oxidative fibres, because their source of ATP is glycolysis. These fibres are best suited for rapid, intense actions, such as short sprint at maximum speed.
