前言：
　　棒球投手在學習一種新的變化球時，整體投球動作中的肩關節、肘關節、腕關節及膝關節都會有些許的變化和調整，因此能知道學習一種新的變化球並不是相當容易。
目的：
　　探討國內職業棒球投手直球、滑球與曲球其投球過程中的運動學與動力學參數差異，並為國內建立一套直球、滑球與曲球的投球動作標準。
　　探討國內職業棒球投手在投球後的肌力衰退與關節活動角度變化。
研究方法：
　　本研究以十位職業棒球投手做為受測者。受測者投球前、投球後、投球後第一天和投球後第二天皆量測關節活動角度和肌力，來觀察其投球後關節活動角度和肌力變化。使用三維動作分析系統擷取過肩投球(Overhead)動作的過程，投球內容以直球、滑球和曲球三種球路。統計方法用重複測量變異數分析及配對t檢定分析。設定p<0.05即達顯著差異。
結果：
　　直球與滑球的分析結果，100項運動學參數中，有31項有達到統計上顯著差異，33項動力學參數中，有12項有達到統計上顯著差異；直球與曲球的分析結果，100項運動學參數中，有66項有達到統計上顯著差異，33項動力學參數中，有24項有達到統計上顯著差異；滑球與曲球的分析結果，100項運動學參數中，有67項有達到統計上顯著差異，33項動力學參數中，有27項有達到統計上顯著差異。
　　肌力結果，投球前的肩關節屈曲肌力大於投球後的肩關節屈曲肌力，達統計上顯著差異(p=0.034)，且持續到投球後第二天。
　　關節活動角度結果，投球前的肘關節伸展角度大於投球後的肘關節伸展角度，達統計上顯著差異(p=0.013)，且持續到投球後第二天。
結論：
　　直球和滑球的比較中，其相似度比較高，因為兩者球速都非常快，所以整體動作變化不會太大，僅有在球離手時的微小變化，因此比賽時有混淆打者的作用。曲球的整體動作變化就比較大，因為曲球行進軌跡上的變化差異需要比較大，故在整個動作上會有比較大的差異變化，因此打者若能清楚觀察出差異，能就更清楚預測到球的行進軌跡。投手在進行投擲滑球和曲球時，會產生相當大的肘關節近端軸向力及肘關節內側力，故建議投手加強肘關節附近肌群，避免手肘部位的運動傷害發生。
　　肌力在投球後肩關節屈曲肌力有持續疲勞到投球第二天的趨勢，因此建議投手可以加強此肌群，以避免在投球運動中產生運動傷害。

Introduction：
　　When the baseball pitchers are learning a new kind of breaking ball, the pitching motion of their shoulders, elbows, wrists and knees need to be adjusted, it is generally known that learning a new breaking ball is a difficult process.
Purpose ：
　　To study the kinematic and kinetic differences among the fastball, slider and curveball, base on these statistics to build up pitching motion database standard posture.
　　To study the decreased muscle strength and range of motion of the pitchers after the pitching.
Methods：
　　Ten professional baseball pitcher. By measuring the range of motion and muscle strength before pitching, after pitching, the first and second days after pitching. Data were collected with an outdoor three dimensional motion analysis system (Raptor-E Cameras, Motion Analysis Corp., Santa Rosa, C.A., U.S.A) which records the progresses of pitchers throwing overhead, pitched fastball, slider and curveball. Statistical methods using repeated measures ANOVA and paired t-test. Significant at P < 0.05
Results：
　　Out of 100 kinematic parameters, 31 kinematic parameters were significantly different between fastball and slider. Out of 33 kinetic parameters, 12 kinetic parameters were significantly different between fastball and slider. Out of 100 kinematic parameters, 66 kinematic parameters were significantly different between fastball and curveball. Out of 33 kinetic parameters, 24 kinetic parameters were significantly different between fastball and curveball. Out of 100 kinematic parameters, 67 kinematic parameters were significantly different between curveball and slider. Out of 33 kinetic parameters, 27 kinetic parameters were significantly different between curveball and slider.
　　Immediately after pitching, the muscle strength significantly decreased in shoulder flexion((p=0.034), and continued until second day after pitching.
　　The results of range of motion, show that after pitching, the range of motion significantly decreased in elbow extension(p=0.013) , and continued until second day after pitching.
Conclusion：
　　Fastball and slider have high similarity in pitching motion, because the velocity of both balls is very fast, so there won't be great difference in pitching motion change, only negligible changes would happen while in the ball release. This ultimately accomplishes the intention of confusing so batters during the game. Curveball is different from fastball and slider in pitching motion, because curveball needs larger trajectory change, and this reflects on the pitching motion. Furthermore, if the batter is able to identify differences, then the moving trajectory of the ball is predictable. While the pitchers throw out a slider and curve ball, it will cause more elbow proximal force and elbow medial force, hence it is suggested that pitchers need to strengthen the elbow muscles, so the occurrence of sports injuries to elbow can be avoided.
　　The shoulder flexion muscle strength fatigue continued until second day after pitching, the suggestion is to strengthen the shoulder flexion muscle, and avoid sports injuries in the pitching movement.

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