What is the term for muscular movement in which the muscle shortens?

The term for muscular movement in which the muscle shortens is "concentric." During concentric contraction, a muscle generates force as it shortens, allowing it to move a load or perform a specific action. For example, when you lift a weight by curling your arm, the bicep muscle contracts concentrically, leading to the shortening of the muscle fiber while generating the necessary force to lift the weight.

Isometric contraction occurs when the muscle generates force without changing its length; the muscle remains at a constant length even while under tension. Eccentric contraction, on the other hand, is when the muscle lengthens while still generating force, such as when lowering a weight back down. Isotonic describes a situation where the muscle changes length while maintaining constant tension, which encompasses both concentric and eccentric movements but does not specifically refer to shortening alone. Therefore, the most accurate term for the type of contraction that shortens the muscle is concentric.