Red muscle fibres

White muscle fibres

Thinner, darker colour, slow contraction rate.

Thicker, lighter in colour, fast contraction rate.

Have numerous mitochondria and myoglobin

Have less number of mitochondria and myolobin

Less accumulation of lactic acid

More accumulation of lactic acid.

They do not get tired soon and can contract for prolonged durations without fatigue.

They are adapted for fast and strenuous work for short intervals and soon get fatigued.