Consistency of performances in the Tkatchev release and re-grasp on high bar

Abstract

The Tkatchev on the high bar is a release and re-grasp skill in which the gymnast rotates in a direction during flight opposite to that of the preceding swing. Since the release window is defined as the time during which the gymnast has appropriate linear and angular momentum to ensure the bar can be re-grasped, it was speculated that the release windows for this skill would be smaller than for dismounts that are less constrained. One senior male gymnast competing at national standard performed 60 Tkatchev trials. A four-segment planar simulation model of the gymnast and high bar was used to determine the release windows in 10 successful and 10 unsuccessful performances of the Tkatchev recorded using a Vicon motion analysis system. Model parameters were optimized to obtain a close match between simulations and recorded performances in terms of rotation angle (1 degree), bar displacements (0.01 m), and release velocities (1%). Each matched simulation was used to determine the time window around the actual point of release for which the model had appropriate release parameters to complete the Tkatchev successfully. The release windows for the successful trials were small compared with those of dismounts. The unsuccessful trials were associated with later release and later timing of the actions at the shoulders and hips.

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

“…The coordination precision was determined from the kinematic data collected by Hiley et al (2007) from 20 performances of the Tkatchev. One senior male gymnast competing at national level (mass = 64 kg, height 1.63 m) performed 60 Tkatchev release and regrasps which were recorded using nine Vicon M2 cameras operating at 100 Hz.…”

“…Holvoet et al (2002) demonstrated that an unsuccessful Tkatchev could have been caught had the gymnast released the bar earlier than in the actual performance. In contrast, Hiley et al (2007) found that for another gymnast earlier release in unsuccessful performances would not have enabled the bar to be regrasped. In order to improve the consistency of performance (i.e.…”

“…An initial analysis of the data collected by Hiley et al (2007) was carried out to determine the variability in coordination (timing and angle) with which the gymnast performed actions at the hip and shoulder joints during giant circles prior to a Tkatchev release and regrasp. Subsequently a gymnast -high bar simulation model (Hiley and Yeadon, 2003) was used to optimise the technique in the backward giant circle prior to release in order to increase the consistency of performance.…”

“…Previous experimental research has looked at the mechanical descriptors of the preceding giant circles and the release parameters of the Tkatchev (Gervais and Tally, 1993;Brüggemann et al, 1994). Simulation models have been used to investigate the differences between successful and unsuccessful performances, with attempts to identify how missed regrasps could be corrected (Holvoet et al, 2002;Hiley et al, 2007). Holvoet et al (2002) demonstrated that an unsuccessful Tkatchev could have been caught had the gymnast released the bar earlier than in the actual performance.…”

“…For a successful performance the gymnast must have sufficient linear and angular momentum at release to place the gymnast in a position to regrasp the bar at the end of the flight phase. Hiley et al (2007) determined the release timing window of the preceding giant circle for 10 successful and 10 unsuccessful Tkatchev attempts. The release timing window was defined as the interval for which the gymnast had sufficient linear and angular momentum for a successful performance.…”