Optimum Technique for Generating Angular Momentum in Accelerated Backward Giant Circles Prior to a Dismount

Abstract

In men’s artistic gymnastics the backward giant circle on the high bar is used to produce the angular momentum that the gymnast needs for executing somersaulting dismounts. Dismounts in which the gymnast performs two somersaults in the layout (straight body) position require the greatest angular momentum. However, it appears there are two distinct techniques that elite gymnasts use when performing backward giant circles prior to a double layout somersault dismount. The “traditional” technique has been superseded by the “scooped” technique which is now used by the majority of elite gymnasts. To determine whether the scooped technique is better at producing angular momentum, a simulation model was used to optimize the angular momentum about the mass center at release. The model was evaluated using data obtained from a force/video analysis of accelerated giant circles. The model was able to estimate the reaction forces measured by strain gauges on the bar to within 9% of the peak forces, and the body rotation angle to within 1% of total rotation. During the optimizations, the joint angle time histories of the model were manipulated in order to maximize the angular momentum about the model’s mass center at release. Two optima were found which were characteristic of the two backward giant circle techniques used by elite gymnasts. The traditional technique produced more angular momentum than the scooped technique, although both were capable of producing sufficient angular momentum for a double layout somersault dismount. This suggests that the preference of elite gymnasts for the scooped technique must be based on factors other than the production of angular momentum.