Solution

Red muscle fibres are thin muscle fibres. They can work for longer periods without fatigue. This is possible because of following reasons:
$$*$$ Plenty of myoglobin means plenty of oxygen supply.
$$*$$ They depend on aerobic respiration for energy. Hence, lactic acid is not formed in these muscles.
$$*$$ There are plenty of mitochondria in these muscles: which means plenty of stored ATP.
$$*$$ These muscles work slowly and hence work for longer.