CHANGE OF DIRECTION SPEED IN SOCCER: HOW MUCH BRAKING IS ENOUGH?
CHANGE OF DIRECTION SPEED IN SOCCER: HOW MUCH BRAKING IS ENOUGH?
复制标题
足球中的变向速度：多少制动才足够？
作者：
K. Hader;D. Palazzi;M. Buchheit
本研究的目的是检验：1)一种新的计时系统的有效性和可靠性，以评估在改变方向（COD）期间的运行运动学，2)改变方向速度的决定因素。12名年轻的足球运动员进行了三次20米短跑，要么是直线冲刺，要么是45度或90度冲刺。使用计时门和两个同步的100赫兹激光枪来监测冲刺，以跟踪玩家在COD之前，期间和之后的速度。效度分析显示，与定时门相比，激光估计的偏差从小到小，典型误差从小到中等。可靠性是变量相关的，典型误差小（峰值速度时的距离）大（峰值减速时的距离）。运动学变量与角度相关，峰值速度可能较低，在COD期间的最小速度几乎肯定较慢，并且在90 -COD与45 -COD冲刺时几乎肯定会达到更大的减速。在两个冲刺角度下，COD的最小速度与冲刺成绩有很大的相关性。与大多数其他自变量的相关性尚不清楚。新的计时系统显示出可接受的有效性和可靠性水平，以评估一些选定的运行运动学在COD冲刺。在COD过程中保持高速的能力可能是COD速度的决定因素。
The aims of the present study were to examine: 1) the validity and reliability of a new timing system to assess running kinematics during change of direction (COD), and 2) the determinants of COD-speed. Twelve young soccer players performed three 20-m sprints, either in straight line or with one 45o- or 90oCOD. Sprints were monitored using timing gates and two synchronized 100-Hz laser guns, to track players’ velocities before, during and after the COD. The validity analysis revealed trivial-to-small biases and smallto-moderate typical errors of the estimate with the lasers compared with the timing gates. The reliability was variable-dependent, with trivial- (distance at peak speed) to-large (distance at peak deceleration) typical errors. Kinematic variables were angle-dependent, with likely lower peak speed, almost-certainly slower minimum speed during the COD and almost-certainly greater deceleration reached for 90o-COD vs. 45oCOD sprints. The minimum speed during the COD was largely correlated with sprint performance for both sprint angles. Correlations with most of the other independent variables were unclear. The new timing system showed acceptable levels of validity and reliability to assess some of the selected running kinematics during COD sprints. The ability to maintain a high speed during the COD may be the determinant of COD-speed.