HILEY, M.J. and YEADON, M.R., 2003. Optimum technique for generating angular momentum in accelerated backward giant circles prior to a dismount. Journal of Applied Biomechanics, 19 (2), pp. 119-130
In Men's Artistic Gymnastics the backward giant circle on high bar is used to produce the angular momentum that the gymnast needs to perform somersaulting dismounts. Dismounts where the gymnast performs two somersaults in the layout (straight body) position require the greatest angular momentum. However, there appear to be two distinct techniques used by elite gymnasts 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 The “traditional” technique has been superseded by the “scooped” technique which is now used by the majority of elite gymnasts.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 was better at producing angular momentum a simulation model was used to optimise the angular momentum about the mass centre 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 the total rotation. During the optimisations the joint angle time histories of the model were manipulated in order maximise the angular momentum about the model’s mass centre 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 techniques were capable of producing sufficient angular momentum for a double layout somersault dismount. As a consequence the preference of elite gymnasts for the scooped technique must be based on factors other than the production of angular momentum.