壘球風車式投球不同擺臂技術之運動生物力學分析

Biomechanical Analysis of Two Kinds of Arm Techniques during Softball Pitching Using the Windmill Style

本研究之主要目的是要了解壘球風車式投球動作中兩種不同後擺臂技術，在動作上的異同點，以提供教練、選手在訓練上的參考。以兩名國家亞奧運級女子快速壘球投手為施測對象，用兩部Peak高速攝影機（120Hz；12000）同步擷取投球期間之三度空間運動學參數，並進一步計算此期間投擲臂之轉動慣量與角動量的變化。實驗結果發現，不同後擺技術投擲臂在準備期與傳輸期前期的動作表現有明顯的差異，在此階段，直臂式後擺者有較大的轉動慣量（左腳著地時：直臂式0.34kg＊m2＞屈肘式0.17kg＊m2）與角動量（左腳著地時：直臂式3.92kg＊m2s＞屈肘式2.11kg＊m2s），且其投擲臂的肘與腕關節速度第一峰值亦較屈肘式大（肘關節：直臂式5.95ms＞屈肘式5.19ms；腕關節：直臂式9.38ms＞屈肘式5.88ms）。而在傳輸後期與加速期時兩種後擺式投法在動作表現上卻無明顯的差別。故建議採直臂式後擺投法者需有較佳的肌耐力，而屈肘式後擺投法則建議應有較大的瞬間爆發能力，又此投法在傳輸期前期上臂的動作較為複雜，故投擲臂在與下肢動作間的時宜搭配與協調上亦要較佳。The purpose of this study was to investigate the differences between two kinds of softball pitching technigues that involve pitching the arm backward. Two high skilled female fastpitch softball pitchers served as subjects. Two high-speed video cameras (120 frames/s) were synchronized to collect the arm motions during softball pitching. Angular momentum of the pitching arm was then calculated from these kinematic data and from the moment of inertia of the arm. The results indicated that the first-peak velocity (elbow: straight-arm backward style 5.95m/s> curve-arm backward style 5.19m/s; wrist: straight-arm backward style 9.38m/s> curve-arm backward style 5.88m/s), moment of inertia(left leg landing: straight-arm backward style 0.34 kg*m2> curve-arm backward style 0.17 kg*m2), and angular momentum (left leg landing: straight-arm backward style 3.92 kg*m2/s> curve-arm backward style 0.17 kg*m22.11 kg*m2/s) were larger for the straight-arm backward style during the preparation stage and of the transmission stage. It is suggested that the pitchers need to have better muscle endurance for the straight-arm backward style. However, the pitchers must have more muscle power and coordination for the curve-arm backward style.