Institute for Health and Sport, Victoria University , Melbourne , Australia.
Sports Biomech. 2019 Dec;18(6):608-621. doi: 10.1080/14763141.2018.1452970. Epub 2018 May 22.
In football, kicking with high ball velocity can increase scoring opportunities and reduce the likelihood of interception. Efficient energy transfer from foot to ball during impact is important to attain a high ball velocity. It is considered impact efficiency can be increased by reducing the change in ankle plantarflexion during foot-ball impact. However, conflicting evidence exists, questioning its effectiveness as a coaching cue. The aim of the present study was to systematically analyse joint stiffness, foot velocity and impact location with a mechanical kicking machine to determine if change in ankle plantarflexion during foot-ball impact and ball velocity are influenced. Sagittal plane data of the shank, foot and ball were measured using high-speed video (4,000 Hz). Increasing joint stiffness reduced change in ankle plantarflexion and increased ball velocity from a greater effective mass. Increasing foot velocity increased change in ankle plantarflexion and increased ball velocity. Distal impact locations increased change in ankle plantarflexion and reduced ball velocity as coefficient of restitution decreased. These results identify that change in ankle plantarflexion is a dependent variable during foot-ball impact and does not directly influence ball velocity. Coaches can assess ankle motion during impact to provide feedback to athletes on their impact efficiency.
在足球中，高球速踢球可以增加得分机会，降低被拦截的可能性。在撞击过程中，从脚到球的高效能量传递对于获得高球速很重要。人们认为，通过减少脚球撞击过程中踝关节跖屈的变化，可以提高撞击效率。然而，现有的证据相互矛盾，对其作为教练提示的有效性提出了质疑。本研究的目的是使用机械踢球机系统地分析关节刚度、脚速和撞击位置，以确定脚球撞击过程中踝关节跖屈的变化和球速是否受到影响。使用高速摄像机（4000 Hz）测量了小腿、脚和球的矢状面数据。增加关节刚度会减少踝关节跖屈的变化，并使球速从更大的有效质量增加。增加脚速会增加踝关节跖屈的变化，并增加球速。随着恢复系数的降低，远端撞击位置会增加踝关节跖屈的变化，并降低球速。这些结果表明，在脚球撞击过程中，踝关节跖屈是一个依赖变量，不会直接影响球速。教练可以评估撞击过程中的踝关节运动，为运动员提供关于其撞击效率的反馈。
