Publication:

棒球投手練習過程的下肢動作協調

本研究的目的是通過下肢的運動及動力學分析，探討優秀運動員及初學者投球過程中下肢的運動學及動力學特徵差異及初學者不同練習階段的力矩變化。實驗以1名優秀選手及3名初學者為研究對象，3名初學者並接受6週的投球訓練及4次的檢測。檢測時以VICON三度空間動作分析系統（250Hz）同步AMTI測力板（1000Hz）記錄實驗參與者的運動學及動力學各項數據，並以Euler角、牛頓方程式與Zatsiorsky及Seluyanov的人體肢段參數進行實驗參與者的下肢關節力矩及功率計算。並將3名初學者不同練習階段的力矩以單因子變異數分析法比較各階段的行為改變。運動學上的結果發現，在優秀運動員在抬腳階段前腳髖關節角度較大，同時後腳彎曲速度較小；在跨步階段能將後腳保持在旋內角度，控制後腳髖、膝關節同時伸展。在出手前階段，前腳髖關節能有效將彎曲及旋內動作減速並反轉。動力學上的結果發現，優秀運動員在跨步階段後腳伸展力矩的最大值依膝、髖關節的時序出現；在出手前階段，前腳伸展最大值同樣依膝、髖關節出現，伸展力矩最大值由下而上，由後到前的出現時序形成了一個加速─減速系統，有效率的將動量上傳。在不同練習階段中，初學者皆在第四週有較大變化，初學者間的各別差異相當高，這些改變卻不一定能增進球速。推測初學者是由較易改變的關節力矩開始進行。這項結果提供了學習是非線性改變的間接証據。

The purpose of this study is to compare the kinematics and kinetic difference between elite athletic and beginners, and compare the moment of bingers in different practice stages using lower limb’s kinematical and kinetic analysis. One elite player and three beginners served as participates in this study. three bingers accept six weeks training and four times data collecting. VICON three dimension motion analyze system （250Hz）and AMTI force plate（1000Hz）were used to collect the kinematics and kinetic data. Then Eular equation, Newton equation, and Zatsiorsky & Seluyanov’s body segment parameters were used to calculate the moment and power data. One-way ANOVA were adopted to analyze the bingers’ lower limbs toque in difference stages. According kinematical result, elite player has more bend angle in hip joint, and less bending speed in back leg during wind up. During stride, elite player can keep inner rotation in back hip joint and control hip joint and knee joint to extend in the same time. Before ball releasing, elite player can decelerate and inverse bending and inner rotation speed in front hip joint. According kinetic result, max back leg extending moment of elite player appears from knee to hip during stride. Before ball releasing, the max front leg extending moment appears follow the same pattern. The max leg extending moment appearing from down to up, and back to front create an acceleration to deceleration mechanic, transfer momentum to body effectively. In different practice stages, all beginners have more change in the forth week, but changes between beginners are different. The changes may not gain ball speed, we suppose the beginners changes from the joint that easiest changes. This result support that learning is not a linear process.