Abstract:
The purpose of this study was to examine the kinematic variables of perfect side scale with split in rhythmic gymnasts. Twelve female rhythmic gymnasts, aged between 15-25 years as the participants. Eight high-speed infrared-based and video based cameras were used to collect the kinematics variables. Eight retro reflective markers were placed on body of each participant to find angular velocity and acceleration of trunk angle with XY axis, leg angle with YZ axis and hip angle and linear velocity and acceleration of trunk, thigh, shank. Each participant was allowed 10 times of side scale with split, hold on 1 second and rest between repetition 1 minute. Twenty complete motions, which could raise the leg to be parallel to the YZ axis in 0±5 degree and side bended the trunk to be parallel to the XY axis in 0±5 degree. On the other hand, the incomplete motions, which could not raise leg and side bended the trunk down to XY and YZ axis respectively. Twenty incomplete motions, which raised the leg in maximum angle with YZ axis were analyzed. Compared mean and standard deviation between groups with dependent t-test, with a significant different at p-value < .05. The results showed significant different between complete and incomplete motions of average angular velocity of leg angle compared with YZ axis and maximum angular velocity of hip angle, average and maximum linear velocity of thigh and leg. Moreover, there were significant different of average linear acceleration of thigh, time to peak of trunk acceleration and movement time of the preparation phase. In addition, there was no significant different in linear velocity, linear acceleration, angular velocity and angular acceleration of trunk and time to peak velocity between complete and incomplete motions. In conclusion, these findings demonstrated that the complete of side scale with split pose should raise the leg with acceleration to increase the velocity in initial phase of movement, after that the velocity of leg movement should decrease along with side bending of trunk to keep the posture balance. Therefore, the gymnasts should have strength and power of leg muscle, especially in initial movement of leg raising. Accompany with muscle flexibility and coordination with muscles in other parts for posing in side scale with split. Thus, it can be said that the angular and linear velocity of hip was the important factors to do side scale with split pose, and the coaches and athletes should apply to develop the training program for rhythmic gymnasts.