The mechanics of the backward giant circle on the high bar

In Men's Artistic Gymnastics the backward giant circle on the high bar is used to generate the rotation that the gymnast needs to perform the release-regrasp and dismount skills. Bauer (1983) presented a point mass model of high bar circling which indicated that ideally a gymnast should flex around the lowest point and extend around the highest point of a giant circle in order to maximise the increase in energy. In practice gymnasts follow this technique in only a general sense and flex after the lowest point and extend before the highest point. A four segment planar simulation model of a gymnast was developed to investigate these differences in technique. The model comprised arm, torso, thigh and leg segments with a damped linear spring connecting the arm and torso segments. The high bar was also modelled as a damped linear spring. The model was driven using time histories of hip and shoulder angles. It was found that the simplifications introduced into Bauer's model by neglecting segmental inertias and the elastic characteristics of the gymnast and the bar were not responsible for the differences between the ideal technique and the typical technique of gymnasts. The technique differences could be accounted for by limitations on the torques that are exerted at the shoulder and hip.