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壘球風車式投球跨步腳地面反作用力分析

Softball Windmill Pitch Stride Leg Ground Reaction Force Analysis

Abstracts


投手投球時是由下肢、軀幹到上肢的一種肢體鏈結的動作,投手下肢跨步腳前跨帶動身體往前,投擲臂迴旋加速將球丟出,跨步腳之於投手是必須保持平衡且穩固。目的:觀察跨步腳著地時的地面反作用力,並且分析在直球與上飄球上的差異性,是否投擲兩種不同球路時地面反作用力會有不同。方法:利用一塊Kistler 9281型測力板測量五位女子甲組風車式壘球投手往前跨步投擲直球與上飄球時的地面反作用力。結果:傳輸期:直球642±9毫秒、上飄球636±105毫秒;加速期:直球119±7毫秒、上飄球120±6毫秒。在地面反作用力垂直向上的分力,直球的最大峰值3.04BW、上飄球3.19BW;前後方向的分力,直球1.36BW、上飄球1.37BW;側向分力,直球0.45BW、上飄球0.46BW。結論:上飄球在地面反作用力的內側分力的變化大於直球。兩種球路在垂直方向的正向力皆大於體重的3~4倍,因此建議選手除了鍛鍊投擲臂肌群外,下肢跨步腳的訓練也是很重要的。

Keywords

直球 上飄球 加速期

Parallel abstracts


Pitching is a movement, composed with lower extremity, trunk, and upper extremity, that be linked with each segment, and is following in a sequence. Stride leg leads body forward, throwing arm rotating speedily, and then throwing the ball by forward lunge. Purpose: To observe landing ground reaction force during pitching straight ball and rise ball. Methods: Kistler 9281 Force plate (Frequency: 1,000Hz) was used to collect the five female softball windmill pitchers. Results: The delivery period (stride-foot up to off) during throwing straight ball and rise ball were 642±9 and 636±105ms separately; The acceleration period (stride-foot off to ball release) during throwing straight ball and rise ball were 119±7 and 120±6ms separately. The peak forces in vertical direction of ground reaction force during throwing straight ball and rise ball were 3.04 and 3.19BW separately; the peak forces in propulsive (+)/braking (-) direction of ground reaction force during throwing straight ball and rise ball were 1.36 and 1.37BW separately; the peak forces in medial (+)/lateral (-) direction of ground reaction force during throwing straight ball and rise ball were 0.45 and 0.46BW separately. Conclusion: The medial force has greater variation than straight ball. The training of the stride leg cannot be ignored as the both of types of peaks of vertical force are more than bodyweight 3-4 times.

Parallel keywords

straight ball rise ball acceleration period

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