Caljouw Simone R, van der Kamp John, Savelsbergh Geert J P
Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit Amsterdam, The Netherlands.
Hum Mov Sci. 2005 Apr;24(2):206-17. doi: 10.1016/j.humov.2005.04.003.
The aim of the experiment was to investigate how bi-phasic hitting movements are organized to comply with both impact and temporal precision constraints. 'Bi-phasic' refers to a sequential movement with a preparatory movement away from the interception location followed by a strike phase. The interception location was fixed, as the motion of the hitting device was constrained to follow a straight path orthogonal to that of the approaching balls. We manipulated the required temporal precision by projecting balls with different constant approach speeds (1, 1.5, and 2m/s). Different impact constraints were imposed by instructing participants first to simply hit the ball and subsequently to hit the ball to a designated target area located either 55 or 105 cm away from the interception location. We determined several kinematic variables and used Principal Component Factor Analysis to classify these variables. The analysis revealed two independent factors: a 'velocity' factor (formed by impact velocity, peak velocity of the preparatory phase, peak velocity of the strike phase, and amplitude of the strike) and a 'timing' factor (formed by onset of the preparatory phase, moment of peak velocity of the preparatory phase, and onset of the strike phase). The 'velocity' factor scaled significantly with the required impact constraint and the 'timing' factor scaled significantly with ball speed.
该实验的目的是研究双相击球动作是如何组织的，以同时满足击球力度和时间精度的限制。“双相”指的是一种连续动作，先是有一个远离拦截位置的预备动作，随后是击球阶段。拦截位置是固定的，因为击球装置的运动被限制在一条与飞来的球的路径正交的直线上。我们通过投射不同恒定接近速度（1米/秒、1.5米/秒和2米/秒）的球来操纵所需的时间精度。通过指示参与者先简单击球，随后将球击向距离拦截位置55厘米或105厘米的指定目标区域，施加了不同的击球力度限制。我们确定了几个运动学变量，并使用主成分因子分析对这些变量进行分类。分析揭示了两个独立因子：一个“速度”因子（由击球速度、预备阶段的峰值速度、击球阶段的峰值速度和击球幅度构成）和一个“时间”因子（由预备阶段的开始、预备阶段峰值速度的时刻和击球阶段的开始构成）。“速度”因子随所需的击球力度限制显著变化，“时间”因子随球速显著变化。
