The longitudinal and cross sectional study of junior high school and high school and college students about sprinting technic to improve sprinting velocity

采用横断面研究和纵向研究相结合的方法，探讨技术因素(无支撑腿的制动力和膝关节角度)与短跑速度的关系。我们在这项横断面研究中使用了第12名男性运动员，在这项纵向研究中使用了第8名不同表现水平的男性运动员。在纵向研究中，我们进行了两次/年、总共四次的测量，主要结果如下。无支承支腿C.G.的离心力约为300N，是垂直力(约1500N)的五分之一。这些结果表明，无支承支腿的离心力对地面反力有很大的影响。

The purpose of this study was investigate relationship between technical factor (braking force and knee joint angle of non-support leg) and sprinting velocity by cross sectional study and longitudinal study. We use 12thmale athletes in this cross sectional study and 8thmale athletes who difference performance level in this longitudinal study. And in longitudinal study we conducted measurements at frequency as two times / year and total four times.The main results were as follows. Centrifugal force of non-support leg C.G. is about 300N, this is 1/5 of vertical force (about 1500N). These results suggest that Centrifugal force of non-support leg C.G.is have a big influence on ground reaction force.