短跑途中跑支撑阶段运动学与动力学特征新研究

采用测力与同步摄像方法,对原始解析坐标数据利用测量到的力的数据计算身体重心的加速度,并采用“积分平滑”的方法研究短跑途中跑支撑阶段身体重心的运动学特征,水平与垂直速度的获得由积分获得。从力的原始数据中分析跑的压心与反作用的方向变化。研究结果显示：短跑途中跑身体重心最低点在整个支撑阶段标准化时刻的30％左右,前支撑阶段运动员有加速用力现象,此加速用力虽影响水平速度,但对提高垂直速度有积极意义,垂直速度在标准化支撑时间的80％处开始下降;途中跑支撑阶段压心从着地时的跖趾骨处急速向踝关节移动后又逐渐向前移动到第二跖关节附近,着地时反作用力的方向有两次向后“突变”。采用的积分平滑运动学数据的技术措施能有效提高计算的精确度。

A new Kinematics and Kinetic analysis of Sprint Running at Supporting Phase

The aim of this study is to explore the character of kinematics and kinetics in supporting phase of sprint running.The acceleration of the mass center of body was calculated by the ground counterforce measured on Kistler force plate.Velocity and"the really mass center of the body"was integrated by the acceleration and the initial velocity,which was fitted using least squire method between the digitizing coordinates from the picture of vidicons and velocity of theoretic dada.The center of the pressure was observed from the force sensor.Results show the mass cen-ter ascend around the moment of30%standardized support time in supporting phase.The runners also exert force to ascend the vertical velocity of the body at the moment of foot touching the ground a hood of the boty's ceuter of gravity although descend the horizontal velocity a little;The COP of the foot was moved from the place of metatarsal to ankle joint,then quickly move forward to second metatarsal.The direction of resultant force of ground counterforce lean backwards twice.Technical method of this study can improve the accuracy of calculation.