双杠弧形上转体180°成支撑的生物力学分析

本文以我国优秀体操运动员为研究对象,对弧形上转体180°成支撑的技术原理进行了生物力学分析。其基本动作要领和主要运动学参数如下:一、身体开始后倒时肩角约为60°旋转半径约为0.4m.0.17秒以后肩角逐渐增大。至第一阶段结束时约为100°。旋转半径为0.6m,重心角速度为6.91弧度/秒,为完成动作储备了足够的机械能。二、伴随肩角逐渐增大的同时,髋关节角度由180°迅速减小,踝关节通过握点向后运动。至第一阶段结束时髋角为24°。身体尽量折紧,为完成动作储备肌肉能量。三、身体重心摆过垂直面后。迅速向前上方伸髋,送腿(踝关节与杠前水平面约成70°角),髋角由小猛然增大,踝关节角速度上升到12.56弧度/秒。带动整个身体快速上升。此时两臂用力压杠。肩角保持100°不变。为迅速伸髋建立牢固的支点。四、在髖关节接近伸直时,两腿予先向左侧转动。接着右手松杠,左臂向后压杠,髋关节完全伸直加速转体90°两手在0.17秒依次换握成屈臂支撑。身体重心比开始升高0.34m。然后继续转体伸直两臂成文撑姿势。

A BIOMECHAN1CAL ANALYSIS FOR SHOOT UP TO SUPPORT WITH HALF TURN ON PARALLEL BARS

This paper makes an analysis for the technical principle of perfor—mance of shooting up to support with half turn biomechanics,takingthe excellent gymnasts of our country as the objects of the study,thebasic essentials for performing the movement and principal parametersof kinematics are as follows:Ⅰ The shoulder angle is about 60° when the body begins to drop back—ward,the revolving radius is about 0.4m.After 0.17 sec the,degree ofshoulder angle increases gradually until the end of the first gradethe shoulder angle is about 100°,revolving radius is about 0.6m and thespeed of the centre of gravity is。6.91 radian/second.So,it has laid upenough mechanical energy for completing the movment.Ⅱ As the shoulder angle increases the hip angle decreases rapidly from180°,the ankle moves backward pass the point of the hold,the hip anegleis about 24°up to the end of the first grade.the body folds up as tight aspossible and stores up the muscular energy for performing the movement.Ⅲ With The centre of gravity of body having passed the vertical plane,straighten the hip and throw the legs fore—upward rapidly(the ankle isabout 70° an angle with the level plane of bars).The hip angle increasesfrom small swift,the anglar velocily of the ankle increases to12.56 radianl/second,thus bringing along the body rising speadlyAt this moment the degree of the shoulder angle keeps in 100°without any change,as a result of making a firm point of su—pport for straightening the hip speedly.Ⅳ When the hip nearly straight,the legs turn to left be—forehand then the right hand pushes away the bar the left armpresses the bar backward with tle straight arm.The hip hasstraightened at all.the body turns 90° at rapid speed.Within 0.17sec,the hands change in turn to bent arm rest.The centre of gra—vity of body rises 0.34m higher thanbeginning level,the body turnscontinuously to support body position with straight arms.