DYNAMICS OF FORWARD SWINGING SKILLS ON THE PARALLEL BARS

Abstract

INTRODUCTION AND PURPOSE: There is a need for and value in studying individual skills on any gymnastic apparatus. Identifying skills that share common elements and could be grouped together may be of greater value, however. On the parallel bars, the back toss (BT) and the backward somersault dismount (BD) appear to share common elements, at least qualitatively. Although both skills have been studied independently and their kinematics have also been presented as a group, their dynamics have not been investigated. The purpose of this investigation was to study the dynamics of the upswing phase of forward swinging skills (FS) on the parallel bars which appear to share common elements. METHODS: Thirty-four FS recorded with a NAC 400 HSV camera were analyzed utilizing an Ariel Performance Analysis System. The analyzed FS were rated by two internationally-qualified judges. Two dimensional position data of four to six body points were digitally smoothed before further analysis. Variables examined were: 1) average vertical and horizontal forces during the upswing phase of FS, 2) reduction of vertical force prior to takeoff, and 3) angular momentum at takeoff. Forces were calculated utilizing the impulse-momentum relationship and normalized by body weight. Angular momentum was normalized for height and mass. RESULTS: Independent t-tests between the BT (n=16) and BD (n=18) revealed a significant (p<.005) difference in average vertical forces during the upswing phase (1.083 vs. 1.116 times body weight for the BD and BT, respectively). Independent t-tests between high- (n=15) and low- (n=19) scored FS revealed significantly smaller horizontal forces during the upswing for high-scored FS (0.582 vs. 0.754 times body weight for high and low scored FS, respectively) and a significantly smaller reduction in vertical forces prior to takeoff for high scored FS. Reductions of 0.483 vs. 0.782 times body weight were seen for high and low scored FS, respectively. CONCLUSIONS: Results of the study revealed that selective dynamic characteristics of the upswing phase of FS on the parallel bars are for the most part similar. The results of the present study also suggest that, in FS, gymnasts score higher when they minimize the horizontal force during the upswing phase and do not significantly reduce the vertical force prior to takeoff.