Analysis of the function of Gastrocnemius and Soleus in ankle joint during jumping by means of physical model

The following actuators were prepared as the actuator of the physical models for jumping. The springs were applied as the extension actuator of the knee and ankle joint, and the wire was applied as the bi-articular muscle Gastrocnemius. Four models were made by combining those actuator. The model (1)was equipped with only knee joint extension actuator. The model (2)was equipped with the knee joint extension actuator and the ankle joint extension actuator. The model (3)was equipped with the knee joint extension actuator and the bi-articular muscle Gastrocnemius. The model (4)was equipped with the knee extension actuator, the ankle extension actuator and the bi-articular muscle Gastrocnemius. The ankle joint of the model (1)was fastened because the ankle joint that was not equipped with actuator was not able to transmit power to the floor. As a result, the relation of the jumping heights of the models was that (3)>(4)>(2)≒(1). Moreover, the relation of the rotary frequency in the air was that (1)>(2)>(4)≒(3). These results indicate that the Gastrocnemius has the functions of increasing jumping height and stabilizing airborne posture, and that the soleus has not those functions.