Abstract
A study was conducted to investigate the characteristics of sprint motion in top-ranking elementary school sprinters. The subjects were 10 first-class elementary school sprinters (sprinter group), and 31 standard elementary school children (control group), all aged 12 years. Measurements were performed for sprint speed, step frequency, step length, and sprint motion in terms of angular kinematics for both groups. In addition, the isokinetic peak torques at 60 and 180 deg/s were analyzed. The results obtained were as follows: The mean values of body height and mass were larger for the sprinter group than for the control group. Isokinetic peak torques during knee extension and flexion (angular velocity; 60, 180deg/s) were greater for the sprinter group than for the control group. The sprint speed, step length, and step frequency of the sprinter group were significantly greater than those of the control group. On the other hand, the support time of the sprinter group was significantly shorter than that of the control group. The relationship between sprint speed and sprint motion in the sprinter group was as follows: The maximal thigh lift angle (θT) showed a negative correlation (r = - 0.369) with sprint speed, and the ankle joint angle at the moment of foot contact (θA-on; r = - 0.619) and the minimal angle of the ankle joint during the foot contact phase (θA-min; r = - 0.372) showed a negative correlation with sprint speed. However, the maximal extension velocity of the ankle joint (ωA) showed a positive correlation (r = 0.326) with sprint speed. Although sprint motion in the sprinter group showed specific features, the correlation between sprint speed and sprint motion was not significant in either group. In particular, positively and negativity were contrary in the relation between θA-on, θA-min and ωA and sprint speed in the sprinter group, compared with the correlations in adult sprinters. The relationship between sprint speed and sprint motion showed that sprint motion in the sprinter group was not always similar to that in adult sprinters.
