Active force is generated from myosin thick filaments bind to thin actin filaments, engaging the cross bridge cycle and ATP hydrolysis. Active force data changes as the resting length of the muscle changes. When the resting length of the muscle is shortened, the active force amount increases. When the resting length of the muscle is lengthened, the active force amount decreases. The change in the active force amount is completely caused by the amount of myosis bound to actin. The shorter the muscle’s resting length is, the more myosis filaments bind to actin filaments.