What is the ability of a muscle to return its original length called?

The ability of a muscle to return its original length is called recoil or relaxation. Relaxation is the process by which a muscle returns to its resting length after contracting. It is an active process that requires energy and involves the breakdown of ATP. During relaxation, the cross-bridges between the actin and myosin filaments detach, and the filaments slide past each other to return the muscle to its original length.