What type of contraction occurs when a muscle lengthens while producing force?

The correct answer is that an eccentric contraction occurs when a muscle lengthens while producing force. This type of contraction typically happens when a muscle is under tension while being stretched, such as when lowering a weight or descending stairs. During this contraction, the muscle fibers are activated and generate tension, but the overall length of the muscle increases, resisting the force of gravity or another external load.

In contrast, concentric contractions involve muscle shortening while producing force, isometric contractions occur when the muscle generates force without changing its length, and static contraction refers to muscle tension held without movement. Understanding these differences is essential for analyzing various movements and muscle functions in physical activities and training.