What happens to muscle during a concentric contraction?

During a concentric contraction, the muscle fibers actively shorten as they generate force. This process occurs when the muscle is working against resistance, allowing movement to take place in a joint. For example, during a bicep curl, when the bicep muscle contracts to lift the weight, it shortens to create the upward movement of the forearm. This shortening results from the sliding filament mechanism within the muscle fibers, where actin and myosin filaments slide over each other to shorten the overall length of the muscle.

In contrast to concentric contractions, eccentric contractions involve the muscle lengthening while under tension, and isometric contractions occur when the muscle maintains the same length despite tension. The oscillation of a muscle does not accurately describe any standard type of contraction recognized in biomechanics. Understanding these distinctions helps clarify the specific nature of muscle actions and their roles in movement during various physical activities.