不同限制對網球正拍擊球動作影響之探討

The Effect of Constraints on Tennis Forehand Stroke

陳佳郁(Chia-Yu Chen)

指導教授 ： 劉有德

國立臺灣師範大學/運動與休閒學院/體育學系/碩士(2011年)

摘要

網球運動是常見的大專院校體育課程之一，對初學者而言正拍擊球是最重要且基本的技術，常見情形是初學者皆能完成對牆擊球的評量要求，但轉移到場地時表現卻差異甚大。目的：探討網球運動初學者正拍擊球動作表現及協調型態，在不同環境和工作限制下的差異及關係。方法：8名網球運動初學者在對牆情境與場地情境，分別執行6公尺與9公尺距離的擊球，記錄成功率，並收取運動學資料、擊球點、擊球前球速，每一次擊球分段處理後，選取成功擊球再串聯進行主成份分析。結果：短球成功率高於長球，對牆成功率高於場地，且距離對於場地的影響顯著大於對牆情境。而短球擊球點較長球前面，對牆擊球點又較場地前面，且長球球速大於短球，場地球速變異情形大於對牆。透過主成份分析可將全身36維的資料縮減至只需4到5個主成份，可以解釋75%以上的動作變異，其中拉拍到揮拍動作為第一及第三成份，非持拍手維持平衡的動作為第二成份，下肢動作及身體肢段的上下動作為第四或第五成份；效果量顯示長球動作幅度大於短球。結論：不同環境與不同距離有其工作難度的分別，且擊球點的早晚可能是影響成功率的因素之一；場地與對牆的動作協調型態並無太大差異，但距離會影響其動作幅度，當距離增加，動作幅度會隨之加大。

關鍵字

網球正拍擊球 ； 主成份分析 ； 協調型態

並列摘要

Tennis is one of the common physical education curriculums in colleges and the forehand stroke is the most important fundamentals. The beginners usually can easily meet the assessment requirement when hitting against the wall, but the performance level significantly dropped when transferring to the court. Purpose: The study investigated the performance outcome and the coordination pattern of the tennis beginners when executing the forehand strokes under different environment and task constraints. Methods: Eight male college students majoring in PE related areas were instructed to execute the forehand stroke under 2 environmental conditions (to the wall and on the court) and 2 distances (6m and 9m from the net/wall). Gyro 3D motion digitizing system (120Hz) was used to capture the movement kinematics of the 12 joints, yielding a total of 36 dimensions of the movement for principal component analysis (PCA). Two synchronized high-speed cameras (200Hz) captured the movements of the participants and the moments of ball contact. These data were analyzed with the Kwon 3D motion digitizing system. Performance outcome was recorded by another digital camera placed on the front of the target areas. Results: The performance outcomes at 6-m were significantly better than those at 9-m; and the performance outcomes in the wall environment were significantly higher than those on the court. The influence of the distance to the court environment was larger than that in the wall environment. The contact points in the short distance were in advance to the long situation. The speed of the ball before contact were higher for the long distance conditions than that for the short distance conditions, and the variability of the ball speed were higher on the court condition than that in the wall condition. The PCA results showed that the 4 or 5 principal components were sufficient to explain over 75% of variance for both environments. The swing movement of the forehand stroke on the court was interpreted by the 1st and 3rd components, and the left hand movement which was to maintain the balance of the swing movement was interpreted by the 2nd component. The 4th and 5th components were related to the lower limbs and right segments of the body movements. For the wall condition, the movements of the 1st, 2ed, 3rd and 4th components were similar to the 1st, 2ed, 4th and 5th components of the court condition, respectively. The results of effective value showed the range of the swing movement of the long distance shots were larger than the short distance shots. Conclusions: The different environments and distances showed different task difficulties, and the ball-racket contact points could also be the key factor for executing forehand stroke successfully. While the range of motion differentiated the long from the short distance strokes, the coordination patterns in both environmental conditions basically were the same.

並列關鍵字

forehand stroke ； Principal Component Analysis ； coordination pattern

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