HILEY, M.J. and YEADON, M.R., 2007. Optimisation of backward giant circle technique on the asymmetric bars. Journal of Applied Biomechanics, 23 (4), pp.300-308.
The release window for a given dismount from the asymmetric bars is the period of time within which release results in a successful dismount. Larger release windows are likely to be associated with more consistent performance since they allow a greater margin for error in timing the release. A computer simulation model was used to investigate optimum technique for maximising release windows in asymmetric bars dismounts. The model comprised four rigid segments with the elastic properties of the gymnast and bar modelled using damped linear springs. Model parameters were optimised to obtain a close match between simulated and actual performances of three gymnasts in terms of rotation angle (1.5°), bar displacement (0.014 m) and release velocities (< 1%). Three optimisations to maximise the release window were carried out for each gymnast involving no perturbations, 10 ms perturbations and 20 ms perturbations in the timing of the shoulder and hip joint movements prior to release. It was found that the optimisations robust to 20 ms perturbations produced release windows similar to those of the actual performances whereas the windows for the unperturbed optimisations were up to twice as large. It is concluded that robustness considerations must be included in optimisation studies in order to obtain realistic results and that elite performances are likely to be robust to timing perturbations of the order of 20 ms.