Output Force at the Endpoint in Human Upper Extremities and Coordinating Activities of Each Antagonistic Pairs of Muscles.

Abstract

Control properties exerted at the wrist joint of human upper extremity were analyzed in terms of control engineering as well as electromyographic (EMG) kinesiology. Analyses were performed on the antagonistic pairs of the mono-articular shoulder and elbow muscles and the antagonistic pairs of bi-articular muscles, under the isometric condition with the submaximal as well as maximal efforts. Activity muscular pattern with the maximal effort showed a tightly coordinating activity pattern among the three pair of antagonistic muscles. Under the submaximal force levels, the tight coordination pattern getting loose and showed widely varied patterns. Some loose coordination patterns could control only limited range of output force directions. The existence of coordination control among the three pair of antagonistic muscles contributed to the position/force control and the stiffness control at the endpoint of the extremity.