How is muscle color related to muscle specialization?

Red muscles (extensor muscles) have large amount of myoglobin (protein transporting oxygen). Red muscles have slow and sustained contraction.

White muscles have less amount of myoglobin than red muscles and less mitochondria. White muscles have fast contraction. They perform fast work for short period of time, red perform sustained work for prolonged period.

Muscle color is related to muscle specialization because it indicates whether muscles are used more for aerobic or anaerobic metabolism. Aerobically respiring muscles that do work over a long period of time have more red oxidative fibers, while anaerobically respiring muscles that do work in bursts have more white glycolitic fibers.