Mitsugi Ogata

Interrelationship among rebound jump ability, vertical velocity and take-off motions at running long jump in the higher graders of elementary school

The purpose of this study was to investigate interrelationship among rebound jump (RJ) ability, vertical velocity and take-off motions at running long jump in higher-grade elementary students. The subjects were 110 boys and 113 girls who were fifth and sixth-graders at elementary school. They were filmed in the takeoff phase, and rebound jump ability (RJ-index = RJ-height / contact time) was measured. The students were dividing into three groups based on RJ ability: Excellent (E), Medium (M) and Poor (P) groups. Measured kinematics during takeoff were compared among these three groups, and relationships between vertical velocity and takeoff motions were studied. The main results were as follows: 1) Boys and girls in E group showed higher touch down, takeoff velocities, vertical velocity at takeoff and longer jumping distance, respectively, than the other groups. Moreover trunk angle during takeoff in E group showed smaller forward inclination, although there was no significant difference all kinematics on knee angle, for either boys or girls. 2) E group in the boys showed a greatest takeoff angle among three groups, and a larger decrease in horizontal velocity and a larger generation vertical velocity during latter takeoff phase, and a smaller foot angle displacement than the other groups. 3) E group in the girls showed a higher vertical velocity at maximum knee flexion than the other groups. 4) The significant correlation in both boys and girls was found between vertical velocity at takeoff and trunk angle at touch down, although no significant correlation was between vertical velocity at takeoff and all sections on knee angle, either boys or girls. The significant correlation in boys was found

Motion analysis of overhand throwing in adult women : Considering the physical fitness factors affecting thrown distance

This study was to examine overhand throwing motions of adult women, Eleven physical fitness test items and measurement of throwing distance (using softha11) were administerd to 96 adult female students. The multiple regression equation to estimate throwing distance was calculated by the stepwise method, The differences between estimated distance and measured distance were calculated. Ten subjects with higher residual were selected as Excellent group, and ten with lower residual were selected as Poor group. Overhand throwing motions of selected subjects were filmed simultaneously from side and overhead view by two cameras. Dynamic variables such as displacement, time, velocity, angle and angular velocity were obtained frorn film analysis. Excellent group showed longer throwing distance (p<e.Ol), while there was no significant difference in fitness test items between two groups. Exceilent group showed higher initial velocity of ball at release (p<O.oo1). Judging from these results, it seems that longer throwing distance was caused by higher initial velocity of ball, and higher initial velocity of ball was produced by rational throwing motions, Characteristics of rational overhand throwing motions of adult women which were verified in this study were as follows: 1) greater backward rotation of shoulder of throwing-hand side in the horizontal plane during preparatory phase (step motion>, 2) greater back-swing of throwing-hand during preparatory phase, 3) faster forward rotation of shoulder of throwing-hand side in the horizontal plane during throwing phase (from front foot contact to ball release), 4) skillfu! whip-like action, 5) well-timed wrist