Hunter Andrew H, Angilletta Michael J, Pavlic Theodore, Lichtwark Glen, Wilson Robbie S
School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
School of Life Sciences, Arizona State University, USA.
J Biomech. 2018 Apr 27;72:159-166. doi: 10.1016/j.jbiomech.2018.03.003. Epub 2018 Mar 13.
In many sports, athletes perform motor tasks that simultaneously require both speed and accuracy for success, such as kicking a ball. Because of the biomechanical trade-off between speed and accuracy, athletes must balance these competing demands. Modelling the optimal compromise between speed and accuracy requires one to quantifyhow task speed affects the dispersion around a target, a level of experimental detail not previously addressed. Using soccer penalties as a system, we measured two-dimensional kicking error over a range of speeds, target heights, and kicking techniques. Twenty experienced soccer players executed a total of 8466 kicks at two targets (high and low). Players kicked with the side of their foot or the instep at ball speeds ranging from 40% to 100% of their maximum. The inaccuracy of kicks was measured in horizontal and vertical dimensions. For both horizontal and vertical inaccuracy, variance increased as a power function of speed, whose parameter values depended on the combination of kicking technique and target height. Kicking precision was greater when aiming at a low target compared to a high target. Side-foot kicks were more accurate than instep kicks. The centre of the dispersion of shots shifted as a function of speed. An analysis of the covariance between horizontal and vertical error revealed right-footed kickers tended to miss below and to the left of the target or above and to the right, while left-footed kickers tended along the reflected axis. Our analysis provides relationships needed to model the optimal strategy for penalty kickers.
在许多体育运动中，运动员执行的动作任务同时需要速度和准确性才能取得成功，比如踢球。由于速度和准确性之间存在生物力学权衡，运动员必须平衡这些相互冲突的要求。对速度和准确性之间的最佳折衷进行建模，需要量化任务速度如何影响围绕目标的离散程度，这是一个此前未涉及的实验细节水平。以足球点球作为一个系统，我们在一系列速度、目标高度和踢球技术条件下测量了二维踢球误差。20名经验丰富的足球运动员对两个目标（高和低）总共进行了8466次踢球。球员们用脚内侧或脚背踢球，球速范围为其最大速度的40%至100%。从水平和垂直维度测量踢球的不准确性。对于水平和垂直不准确性，方差都随着速度的幂函数增加，其参数值取决于踢球技术和目标高度的组合。与高目标相比，瞄准低目标时踢球精度更高。脚内侧踢球比脚背踢球更准确。射门离散中心随速度而变化。对水平和垂直误差之间协方差的分析表明，右脚球员往往会踢偏到目标下方和左侧或上方和右侧，而左脚球员往往沿反射轴方向踢偏。我们的分析提供了为点球手建模最佳策略所需的关系。
