Lance Armstrong is a seven-time winner of Tour de France, which is a bicycle race that covers between 3500 to 4000 kilometers. What type of muscle fiber probably predominates in the legs of bicyclists, who compete in this annual event?
Red fibers
Skeletal muscle fibers can be classified as red fibers, white fibers or intermediate fibers. Red fibers are smaller in diameter; white fibers are larger in diameter. Red fibers have more mitochondria than white fibers. Red fibers make up slow-twitch muscle; white fibers make up fast-twitch muscle. Red fibers are more resistant to fatigue compared to white fibers. Red fibers have more myoglobin (oxygen binding pigment) than white fibers. White fibers store glycogen and use anaerobic metabolism. Red fiber and slow twitch muscle are responsible for endurance, which is necessary for the cyclist who will cover 3500 to 4000 km in a multi stage bicycle race. White fiber and fast twitch muscle are responsible for a burst of power.