MUSCLE PHYSIOLOGY

Detailed explanation-1: -Muscles can only pull and cannot push. Therefore muscles have to work in pairs to move a joint. One muscle will contract and pull a joint one way and another muscle will contract and pull it the other.

Detailed explanation-2: -For instance, in order to flex (decrease the angle of a joint) your elbow you need to contract (shorten) the biceps brachii and other elbow flexor muscles in the anterior arm. Notice that in order to extend your elbow, the posterior arm extensor muscles need to contract. Thus, muscles can only pull, never push.

Detailed explanation-3: -Muscles are wonderful things, but most people really do not know how they work. Your muscles move you by pulling or relaxing. That is all. Muscles cannot push.

Detailed explanation-4: -Each skeletal muscle fiber contains filaments of actin and myosin that shorten the muscle and pull on tendons, which in turn pull on bones and move the body. These movements are described as pushes when the muscle moves away from the body or pulls when the muscle moves toward the body.