[Inability to establish a single equilibrium value for the angle of a joint and its relation to the hysteretic properties of muscle contraction].

The processes of joint angle setting were studied on the simple experimental model of a joint. The model consisted of gastrocnemius muscles prepared on both hindlimbs of the anesthetized cat. The muscles were tied in antagonistic manner with a rotation-type registrator. Depending on the order of the muscle activation two different values of the joint angle were in the model system. It has been shown that indeterminacy of the equilibrium value of the joint angle was caused by hysteretical properties of the muscle contraction.