桌球「側併步」與「交叉步」動作之生物力學分析

Abstract

步法是桌球擊球環節中的一個重要組成部分，如果桌球運動員具有良好的步法，能夠經常保持合適的擊球位置，那就會使擊球的速度、力量、旋轉、弧線、落點得到充分的發揮，有利於提高擊球的技術水準。本研究以八名大專甲組選手為實驗對象，目的在探討「側併步」與「交叉步」兩種不同步法配合兩種移位距離「遠」與「近」之運動生物力學參數;以VICON Motion Capture System擷取人體動作反光球資料以及結合三塊KISTLER測力板測得地面反作用力值，經由Visual 3D軟體計算運動學與動力學參數，同步利用Noraxon無線肌電設備擷取人體肌電訊號；所有參數均利用SPSS19版統計套裝軟體進行計算，以無母數弗里曼二因子變異數分析來進行統計考驗，顯著水準定為α=.05。結果發現：一、側併步步法有較大之重心水平位移（遠距：1.047±0.093m；近距：0.533±0.108m），移動後較接近來球，但也顯示出較大的身體重心高度（遠距：0.534±0.015H；近距：0.528±0.022H），影響擊球的時機。二、交叉步從啟動至引拍到位花費較短的時間（遠距：0.782±0.161s；近距：0.718±0.061s），但到位後又須花較長的時間回擊來球（遠距：0.259±0.029s；近距：0.209±0.039s）。三、較大的移位距離相對增加對下肢肌群激發的需求，以及增加地面反作用力以及關節受力的情形；四組動作總積分肌電有顯著差異的肌群，有些以單位時間的積分肌電比較反而沒有顯著差異存在。建議：穩定的回球動作，以側併步為主要步法；但需要迅速到位擊球的狀況，可以交叉步代替；平時練習要將此兩種步法列入練習項目中，增加其熟練度；增加下肢肌群訓練，以增強其肌力以及肌耐力。In striking, a table tennis play’s footwork is very important. If an athlete has good footwork, and strikses the ball at an appropriate position, he will give the ball with good speed, strength, spin, curve and location, whith will improve his skill level. The purpose of this research was to analyze the biomechanic parameters about two footsteps “side step” and “cross step” with two distance ”far” and “near”. The subjects were eight elite collegiate male table tennis players. The mark trajectories of body motion were collected by the VICON Motion Capture System（300Hz）. In the same time, the ground reaction forces（GRF） data were collected by three KISTLER force plates（1500Hz）. Using Visual 3D software to calculate the kinematic and kinetic data. Collecting the EMG data by the Noraxon wireless EMG system（1500Hz）and calculate the data by MyoResearch XP Master Edition software. All the paremeters were tested by Friedman two-way analysis of variance nonparametric statistical test by SPSS 19, the significant level as α＝.05. The results are：1.There is more horizontal displacement about the”Side step”（far：1.047±0.093m； near：0.533±0.108m）, closing the ball much more after moving than the “cross step”. In the same time, there is higher body COG（far：0.534±0.015H； near：0.528±0.022H） when moving that might effect the timing of striking. 2.There is less time from start to the ready striking position to strike by the ”cross step” （far：0.782±0.161s；near：0.718±0.061s）.In the same time, it costs more time to strike after the ready striking position（far：0.259±0.029s；near：0.209±0.039s）. 3.Farther moving need exciting more lower limb muscles, that bring more GRF and joint force. 4.There is significant difference when comparing the total IEMG from start to striking, but there is no significant difference when comparing the IEMG in a unit of time with some muscle. Suggestion：Stable striking with “side step”; nevertheless if one have to reach the ready striking position in a short time, excuting the “cross step”. Including the two steps to the day-to-day practice may enhance a trainee’s proficiency. Training lower limb muscles would strengthen the muscle strength and endurance.