跳远运动空中技术分析

Analysis of the In-air Technique in Long Jump

运用动态力学理论，建立单腿摆动力学模型和动力学方程，运算推导出人体在腾空阶段由于合理的肢体摆动水平速度出现增量，因而证明人体重心在跳远腾空中不是单质体空间运动轨迹，提出了由于肢体后直、前屈，速度快慢、力量大小的摆动而引起人体速度和位移变化的“动态抛物线”理论；并用加速传感器测试系统测试运动肢体摆动参数及身体在空中的速度变化，对“动态抛物线”理论进行了验证。这与传统的“起跳腾空后，身体重心的运动轨迹在没有外力作用的情况下是不会改变的”理论迥然不同。利用这种理论，可以规范和完善跳远空中技术，提高教学质量和运动成绩。

Using the theory of dynamic mechanics,this study established a mechanics model and equation of one leg swing and got a result that an increment in horizental speed appears during the in-air stage because of reasonable limbs swing,thus proved that the body's center of gravity didn't appear an locus of simple substance's space movement during the in-air stage,and put forward that swing related to the limb's straightening back,bending forward,speed and strenghth caused dynamic parabolas of the acceleration of body and the change of displacement; Using an accelerated sensor,the study examined the change of the swing of the athlete's limbs and the in-air speed of the body, and verified the theory of the dynamic parobola.This theory is quite different from the traditional theory which believed that 'without an external force, the locus of the body's center of gravity won't change when in air'.It is helpful for standardizing and perfecting the in-air technique and for improving the teaching quality and the athlete's performances.