Takahashi K, Elliott B, Noffal G
Faculty of Education, Saitama University, Japan.
Aust J Sci Med Sport. 1996 Dec;28(4):106-13.
Increased topspin in the tennis forehand is produced by maintaining a perpendicular racket-face to the court surface at impact and increasing the trajectory and vertical velocity of the racket-head. These modifications to stroke technique from those previously identified in the flat forehand drive are the result of changes to the movement patterns of the segments of the upper limb. The contributions that the upper limb segment's anatomical rotations make to racket-head velocity at impact depend on both their angular velocity and the instantaneous position of the racket with respect to these movements. Six high performance tennis players were filmed at a nominal rate of 200 Hz by three Photosonics cameras while hitting flat (no spin) and topspin groundstrokes and a forehand topspin lob. The three-dimensional (3-D) displacement histories of 16 selected landmarks were then calculated using the direct linear transformation approach and 3-D individual segment rotations for the upper limb were calculated using vector equations. Significant differences were recorded in the effect that the various segment rotations made to the x-direction (forward) and y-direction (upward) impact velocities of the racket-head. These differences were not reflected in the contributions to racket-head velocity when the absolute velocities were expressed relative to the impact velocity. Trunk rotation, upper arm flexion/abduction, upper arm internal rotation, hand palmar and ulnar flexion all played integral roles in producing impact racket speed.
在网球正手击球中,通过在击球瞬间使拍面与球场表面保持垂直,并增加拍头的轨迹和垂直速度来增加上旋。与之前在平击正手击球中所确定的击球技术相比,这些改变是上肢各节段运动模式变化的结果。上肢节段的解剖学旋转对击球瞬间拍头速度的贡献取决于它们的角速度以及拍相对于这些运动的瞬时位置。六名高水平网球运动员在击打平击(无旋转)、上旋击球和正手上旋高吊球时,由三台Photoonics摄像机以200Hz的标称速率进行拍摄。然后使用直接线性变换方法计算16个选定标志点的三维(3-D)位移历程,并使用矢量方程计算上肢的三维单个节段旋转。记录了各个节段旋转对拍头在x方向(向前)和y方向(向上)的击球速度的影响存在显著差异。当绝对速度相对于击球速度表示时,这些差异并未体现在对拍头速度的贡献中。躯干旋转、上臂屈伸/外展、上臂内旋、手部掌屈和尺侧屈在产生击球拍速方面都发挥着不可或缺的作用。