英文摘要
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The purpose of this study was to analyze 4 gymnastics performing two kinds of back-up rise and vault with 1/2 to hand on the horizontal bar. The data was collected by a JVC-9800 digital video camera (60 Hz), and a 14-segment human body model was used and 19 markers were digitized by the Ariel performance analysis system. Moreover, the individual body segment parameters used in this study were established by the MRI method. This study divided motion of back-up rise and vault with 1/2 to hand into 7 phases by a clear definition and compared kinematic parameters of 4 gymnastics which included the joint angle, the angular velocity, the velocity and the height of CM, the period of each phase and the technique in the air. The results were as follows. First, subjects A & B used more shoulder and hip angular extension and flexion to obtain better motive power. Second, shoulder and hip angular velocity of all subject showed two peaks (at position 4(superscript th) & 6(superscript th)). Third, the horizontal velocity of CM of subjects A & B were lower than those of subjects C & D, but the vertical velocity of CM was higher than that of subjects C & D, so the higher vertical velocity is better for performing Yamawaki. Fourth, subjects A & B have longer duration in downswing and performed take-off technique earlier; therefore, CM would be able to move more rapidly to the vertical direction. Fifth, subjects A & B took a shorter time to complete the off-bar motion, while their hands leave the bar, their lower extremities, shoulder and hip joints were horizontal; after their hands leave the bar, the shoulders rose rapidly, and the lower extremities moved clockwise, and then the whole body was kept straight in the air. When subjects were ready to catch the bar, they both finished the twist motion and their body turned perpendicular. Sixth, subjects C & D took a longer time to complete the off-bar motion, which resulted in hip joints contraction while the bodies were twisted in the air, and when subjects C & D were going to catch the bar, they did not finish the twist motion and their body were in an oblique position.
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