The generation of tension within a muscle. The term muscle action is generally preferred to muscle contraction because the latter implies shortening. This does not always take place. In striated muscle, there are three types of action: the muscle may shorten (see concentric action), it may remain the same length (see static action), or it may lengthen (see eccentric action). In many activities, such as running and jumping, all three types of action may occur in order to perform a smooth, coordinated movement.
Subjects: Sports and Exercise Medicine.