Which of the following best describes isometric contraction?

Isometric contraction occurs when a muscle generates force without changing its length. During this type of contraction, although the muscle fibers are activated and creating tension, they do not shorten or lengthen. This is an essential characteristic that differentiates isometric contractions from other types of muscle contractions, such as concentric (where the muscle shortens while producing force) and eccentric (where the muscle lengthens under load).

In practical terms, an example of isometric contraction includes holding a weight steady without moving it—like holding a plank position. The muscle is engaged and producing tension to maintain the position, yet it does not change length. Understanding this concept is vital in fitness and rehabilitation contexts, as isometric exercises can be used for strength training and stability without putting joints through a range of motion.