|Abstract: ||本研究的目的：運用無線微機電感測器系統(Wireless MEMS sensors system)的量測，分析雙手反拍上旋抽球時，優秀選手與次優秀選手間，在雙手反拍時主要九個運動肢段與球拍振動的加速度與角速度的差異分析。方法：使用微機電三軸加速規與陀螺儀組合而成的無線微機電感測器系統，並擷取優秀與次優秀選手各五位，在雙手反拍上旋抽球時主要十個運動肢段與球拍振動的加速度與角速度資料，再以MS Excel、MatLab作統計分析。結果：1. 在優秀與次優秀選手間配戴感測器時達無顯著差異。2.球拍振動頻譜分析，優秀與次優秀選手在三軸的振動頻譜以全頻有差異、低頻差異較大、中高頻無差異。3.拍面三軸最大加速度平均值有顯著差異。4. 在最小加速度平均值中Y和Z軸有顯著差異。5.在加速度總功率中優秀選手在三軸都有較大的平均值，而次優秀選手在Y、Z軸有較高的平均，兩者間在動作上是有顯著差異。6.從三軸總功率顯示次優秀選手間三軸總功率均值大於優秀選手間平均值，表示次優秀選手對球拍施予較大的力量。7. 因次優秀選手用力時間較長因而震動時間也會變長。8.動力鏈曲線中發現，優秀選手（右手掌、右手腕中、左手掌、左手腕）的X、Z 軸的加速度大於次優秀選手；其次優秀選手（右手掌、右手腕、左手掌、左手腕）以Z軸較大，從三軸方向來看次優秀選手在擊球瞬間，雙手的手掌與手腕過度的用力，因而影響手掌與手腕的轉動而造成Z軸方向的受力過大，因而產生過多失誤。9.身體各肢段右手掌有加速度較大的平均值，表示優秀選手在右手掌瞬間擊球，能控制球拍的穩定性以免造成球拍晃動。10. 優秀選手在左手掌瞬間擊球，能控制球拍的穩定性以免造成球拍晃動，但優秀選手間左右掌都有最大加速度值。11.數據顯示選手在右手腕三軸平均下，優秀選手在右手腕加速度有較大的平均值，也成為未來次優秀選手改進雙手反拍動作的重要指標。12.在左手腕施力差異性，得知未來可以修正左手腕問題並加強手腕的訓練。13.右手肘與左手肘在三軸平均下次優秀選手在加速度有較大的平均值，表示次優秀選手在右手肘施力過大，因而產生動作上的不協調間接影響各關節施力。14. 在腰部的動作上，發現次優秀選手在腰部上最小值與總功率都有較大的平均值，而腰部的肢段需要穩定的旋轉並配合各肢段動力，來完成腰部動作的表現。結論：我們從結果中加速度平均值數據分析來看，（右手腕、左手腕、右手掌、左手掌）優秀與次優秀選手有差異，而（右手肘、左手肘）次優秀大於優秀選手因此也有差異存在，本研究發現優秀選手在上肢段要有較好的協調性，在瞬間擊球時懂得馬上放鬆，這樣才能把各肢段的力量傳達出來。建議：1.從數據分析可清楚的發現，優秀與次優秀選手，雙手反拍動作上最大差異在手腕與手肘，我們可以特別針對兩肢段的數據分析，做為動作修正與加強訓練的依據。|
The purpose of this study was to analyze the differences of the nine limbs, and the acceleration and angular velocity of the rackets between five elite and five sub-elite tennis athletes. While they are two-handed backhand topspinning, the data were collected with the help of the wireless MEMS sensor system, within a tri-axis accelerometer and a tri-axis gyroscope, and analyzed by the Microsoft Excel, MatLab softwares. After comparing the data, fourteen things were found between the elite and the sub-elite athletes:
1. There were no clear differences whether they wear the sensors or not.
2. From the vibration spectrum analysis of the rackets, there are differences at the full frequency, obvious differences at the low frequency, no differences at the medium or high frequency.
3. There are apparent differences between the maximum acceleration average values of the rackets in three axes.
4. The averages of minimum acceleration in Y-axis and Z-axis are significantly different
5. Elite athletes have higher averages of the total acceleration power in three axes, while sub-elite athletes have higher averages in Y-axis and Z-axis. Obvious differences can be seen in their movements.
6. The total power average values in three axes of the sub-elite athletes are higher than the elites’, which means sub-elite athletes give more power to the rackets.
7. The vibration time of the sub-elite athletes lasts longer because they use their power longer.
8. From the curves of the kinetic chains, the acceleration of the elite athletes (right palm, right wrist, left palm, left wrist) in X-axis and Z-axis are higher than the sub-elites’, while sub-elite athletes (right palm, right wrist, left palm, left wrist) show higher acceleration in Z-axis. Thus, sub-elite athletes make more errors because at the moment they are hitting the ball, their palms and wrists overuse their power in Z-axis.
9. Elite athletes show higher average of the acceleration of the right palms, which means while they are hitting the ball, they hold the rackets with more steadiness without shaking.
10. The left palms of the elite athletes can help steadily control the racket, and both the right and left palms of the elite athletes have the maximum acceleration.
11. The average acceleration of the right wrist in three axes of the elite athletes are higher than the sub-elites’, which can be the targets to help improve the sub-elite athletes.
12. From the differences shown about left wrists, solutions can be found to help train the athletes’ wrists.
13. Sub-elite athletes show higher average acceleration of the right wrists and left wrists in three axes, which means sub-elite athletes overuse their elbows to cause the incoordination.
14. Sub-elite athletes show higher average of the minimum and the total power of the waist; however, the waist movement needs to be done with stable turnaround to cooperate with each limb.
From the analyses of the average acceleration statistics, differences exist between the elite and sub-elite athletes (right wrist, left wrist, right palm, and left palm). And the average statistics of the sub-elite athletes are larger than the elites’ in the right elbow and the left elbow. Thus, it can be found that the upper limbs of the elite athletes have better coordination. Elite athletes relax themselves immediately after hitting the ball, which can easily bring out the power of each limb. According to the statistical analyses, the biggest differences between elite and sub-elite athletes are the wrist and the elbow. In the future, these two parts of the body can be assessed for further understanding of the movements. This can allow tennis athletes and coaches to improve the performance of tennis techniques.