目的：瞭解不同程度運動員在揮拍過程中球拍撓度的差異，並探討不同勁度羽球拍在實際擊球中對於擊球點撓度、打擊感受之影響，可做為日後羽球拍選擇的依據之一。方法：在六隻不同勁度的羽球拍中桿尾端黏上應變規、加速規黏貼於受試者持拍手的第3掌骨與近節指骨交接處，以1600Hz擷取頻率收取羽球拍在全力殺球過程中的撓度變化以及振動訊號，比較不同運動水平受試者在擊球點撓度的差異；使用無母數弗里曼二因子等級變異數(Friedman two-way ANOVA test)考驗球拍勁度對於前擺期的差異；使用魏克生符號等級檢定(Wilcoxon Signed-Rank Test)比較高水平跟一般水平的受試者在前擺期時間是否有差異，顯著水準均定為α<.05。結果：高水平受試者皆在羽球拍撓度為負時候打到羽球，代表擊球時球拍是向後彎曲，此時球拍中桿本身彈性方向與揮拍方向同，可以使用球拍中桿的彈性來增加揮拍速度與球速。但在一般水平的受試者有4-5隻羽球拍是在羽球拍撓度為正時候打到羽球，代表擊球時球拍向前彎曲，這樣會減低揮拍速度與球速。而不同羽球拍勁度對於打擊感受、前擺期未達顯著差異。結論：打擊振動與打擊感受間並無相關，可加入其他因素如重量、平衡點等再作探討。勁度不影響擊球前擺期的時間，高水平的受試者在打到羽毛球時，中桿為向後偏擺，球拍的彈性速度是向前，高水平受試者較能利用到球拍中桿的彈性位能，一般水平的受試者則不一定，在挑選球拍時，若可以測量使用者擊球時的球拍撓度，可以當作是挑選球拍的依據之一。

Purpose：To understand the effect of different kind of shaft stiffness on deflection and 'feel' during badminton smash and to understand the different level athlete on shaft deflection during smash. The result of the study will be taken as indexes to select badminton racket in the future. Methods: Strain gauges stuck on the end of shaft were used to measure the deflection of the racket and an accelerometer stuck on 3rd metacarpal bone were used to measure amplitude during smash at 1600 Hz. Deflection from 6 different shaft stiffness racket were compared at ball impact. Friedman test was used to examine the difference of 'feel' and shaft deflection .Wilcoxon Signed-Rank Test was used to examine the difference of 'feel' and shaft deflection between elite and general athletes. The significant level was set at .05. Result：Direction movement and recovery of racket are the same when elite athletes play a smash. Elite athletes let racket bending backward at ball impact. It can use elastic strain energy to increase the swing-velocity and ball-velocity. But some of general athletes can't do it like elite athletes. No significant differences of shaft stiffness were found for 'feel' and amplitude. Conclusion：Elite athletes used elastic energy of racket more than general athletes at ball impact. No correlation between 'Feel' and vibration was noted. Shaft deflection can be used as a basis for selecting the racket.

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