KINES 300 Lecture Notes - Lecture 15: Rectus Femoris Muscle, Alpha Motor Neuron, Myocyte

• School: American River College
• Department: Kinesiology
• Course: KINES 300
• Professor: Kiefer

Document Summary

Atrophy is greater in type ii muscle fibers than type i. As you get older, you loose type ii muscle and proportionally gain type i. Muscle fibers are part of a motor unit: Motor unit = alpha motor neuron, axon, and all the muscle fibers innervated. The cns controls muscle activities through controlling motor units. Defined by the number of muscle fibers it controls. A small size of motor unit controls type i muscle fibers. A medium size of motor unit controls type iia muscle fibers. A large size of motor unit controls type iib muscle fibers. Motor units are recruited from smallest to largest. If you recruit all motor units at once, you will fatigue very quickly and easily. Small are recruited first and if they are not enough, more are recruited to save energy. Low intensity, high repetition exercises help improve endurance. High intensity, low repetition exercises help improve power.