Function of Antagonistic Pair of the Bi-articular Muscle of Lower Limb During Toe Contact

Abstract

We attempted to clarify the mechanical function of bi-articular muscles in the lower limb in the toe landing motion which enables the running motion. In the present study, the main working muscle was first clarified by electromyography analysis. An experimental analysis was subsequently performed using a real machine model, taking the protagonist muscle into consideration. The results of the electromyography analysis clearly demonstrated that stability of the body trunk involved switching the activity of the antagonistic pair of bi-articular muscles in the femur, suggesting a parallel link function. Based on this, an experimental analysis was performed using a real machine model with bi-articular muscles in the lower limb linked in parallel. The stability of the center of gravity of the model during dynamic motion due to switching of the muscle activity confirmed the parallel linkage, thus clarifying the involvement of the bi-articular muscles in the lower limb in body trunk stability at the time of toe landing.