During Heavy physical work or strenuous exercise the demand for oxygen increases many fold. The oxygen does not diffuse into the skeletal muscle fibres at the required rate. Skeletal muscle fibres contain an oxygen storing pigment myoglobin.
There are two types of muscle fibres :
1. Red (dark)
2.White (pale)
Red muscle fibers are richer in myoglobin content than the white muscle fibres. Therefore, red fibres can utilize the oxygen stored in myoglobin to continue energy production over prolonged periods by aerobic oxidation of glucose.This enables them to perform sustained work over a long period.
On the contratory, white fibres produce the energy needed for very fast and severe work by glycolysis, mainly because sufficednt oxygen is not immediately available for them for such work.
But white muscles accumulate lactic acid and get fatigued in a short time. Thus,athletes with a higher proportion of red fibres in their muscles are physiologically better equipped for sustained events such as cycling, running or swimming over long distances. Athletes with a higher proportion of white fibres in their muscles are equiped for fast, intense but short activities such as sprint, short put etc.
There are two types of muscle fibres :
1. Red (dark)
2.White (pale)
Red muscle fibers are richer in myoglobin content than the white muscle fibres. Therefore, red fibres can utilize the oxygen stored in myoglobin to continue energy production over prolonged periods by aerobic oxidation of glucose.This enables them to perform sustained work over a long period.
On the contratory, white fibres produce the energy needed for very fast and severe work by glycolysis, mainly because sufficednt oxygen is not immediately available for them for such work.
But white muscles accumulate lactic acid and get fatigued in a short time. Thus,athletes with a higher proportion of red fibres in their muscles are physiologically better equipped for sustained events such as cycling, running or swimming over long distances. Athletes with a higher proportion of white fibres in their muscles are equiped for fast, intense but short activities such as sprint, short put etc.
