Achieving consistent performance in a complex whole body movement: the Tkatchev on high bar.

If the magnitude of timing and angle variability in whole body coordinated movements were known, this would allow more realistic levels of variability to be included within optimizations of technique. The aim of this study was to determine the technique for improved consistency of performance of the Tkatchev release and regrasp on high bar, while incorporating realistic levels of coordination precision. The effect of gymnast strength and flexibility on consistency of performance was also investigated. Twenty trials (10 successful and 10 unsuccessful) by one national gymnast were recorded using an automatic motion capture system and were analyzed to determine variability in coordination of the giant circle technique prior to release. The standard deviation in the hip and shoulder angles and timings at four key instants in the gymnast's performances were 2.3° and 12 ms. A gymnast-high bar simulation model was used to optimize the technique in the giant circle to maximize the success percentage for which the gymnast could release and regrasp the bar with coordination variability introduced into each simulated technique. When the optimal solution was perturbed randomly in 1000 simulations to the level seen in the gymnast performances 69% produced a successful performance compared with only 17% for the gymnast. An increase in strength (by 25%) and a reduction in variability (by 25%) lead to improved consistency (91% success rate). Flexibility did not appear to play a role as none of the optimizations approached the bounds set by the gymnast's performances.