Which type of contraction occurs when a muscle lengthens under tension?

Eccentric contraction occurs when a muscle lengthens while under tension. During this type of contraction, the muscle is actively resisting a force that is greater than the tension generated by the muscle itself. This often happens during movements where the muscle is slowing down or controlling the descent of an object, such as lowering a weight or going down a hill.

For example, during the descent of a squat, the quadriceps must lengthen under the weight of the body, which is an eccentric contraction. This type of contraction is crucial for various functions, including shock absorption and the control of movements, as it allows muscles to manage the forces exerted on the body more effectively. Understanding eccentric contractions is vital for trainers as they play an essential role in injury prevention and rehabilitation, as well as enhancing athletic performance.