An eccentric muscle action occurs when:

An eccentric muscle action occurs when the pulling force generated by a muscle is less than the resistance force acting against it. This situation typically occurs when a muscle elongates while under tension. For example, during the lowering phase of a bicep curl, the bicep contracts eccentrically as it controls the descent of the weight, allowing the muscle to extend while still generating force.

This type of muscle action is essential for activities that involve deceleration, such as landing from a jump or controlling movement through a range of motion. Eccentric actions are key in preventing injury and improving overall strength, as they require the muscle to maintain tension despite being lengthened. Understanding this concept is crucial for designing effective corrective exercise programs that address muscle imbalances and enhance performance.