2006 Volume 10 Issue 1 Pages 27-41
This study investigated the dynamic mechanism and technique, which particularly focused on horizontal rotation, of double leg circles (DLC) on the pommel horse. The forces exerted on the pommel during DLC performed by 17 male university gymnasts were recorded using a pommel horse model containing force plates, and the performances were videotaped with two digital video cameras. Based upon the result that three judges scored each of the performances on the video, the best 5 (S-group) and worst 5 (U-group) out of the 17 subjects were analyzed. Changes in the horizontal velocity of the center of mass (CM) accorded with the change of tangential components of horizontal reaction forces exerting on CM. The horizontal velocity of CM was minimal during both-hand support phase (BHS), and maximal during the one-hand support phase (OHS). The horizontal velocity of the ankles and the horizontal velocity of CM of the head and trunk were minimal during OHS, maximal during BHS. However, the horizontal velocity of CM of the total leg had no apparent peak. The mechanical energy of CM decreased during BHS. The body lateroflexed to the direction of the releasing hand during OHS, and the direction of lateroflexion changed during BHS. In the comparisons between S-group and U-group, the S-group showed smaller angles of body flexion, but the two groups were almost the same in the angle of body lateroflexion. From these results, it was thought that the DLC was composed of two kinds of rotations: rotation of CM and rotation of the body about CM. The rotational velocity of the leg was influenced by their rotations and the ratio of influences varied with phases. And the importance of lateroflexion of the body during the DLC was suggested.
