大專棒球選手在不同擊球高度下之揮棒動作分析

Abstract

目的：瞭解不同層級棒球打者在四種不同高度擊球時，揮擊期的動作過程差異。方法：受試者為大專甲一級棒球選手10名、甲二級棒球選手10名，共20名球員(年齡：22.85±2.37歲、174.65±6.18公分、70.01±7.19公斤)。以Vicon MX13+紅外線攝影機10台，與兩塊KISTLER測力板同步收集揮棒過程的3D影像及力值資料，並搭配FASTEC高速攝影機一台，拍攝球飛行之影像。資料處理以Nexus與Kwon 3D軟體分析打者揮擊期的運動學與動力學參數，並使用混合設計二因子變異數分析考驗不同層級打者及不同擊球高度下的參數差異，顯著水準設為α=.05。結果：甲一級打者在揮擊期中有較大的前腳前後方向地面反作用力峰值(0.61倍體重>0.47倍體重)及更早的前腳前後方向與垂直地面方向反作用力峰值發生(前後方向：68.81%<76.15%；垂直地面方向：71.35%<80.58%)，也有更快的棒頭速度與擊球初速之發揮(最大棒頭合速度：30.92m/s>27.37m/s；擊球初速：31.49m/s>27.74m/s)。而無論是甲一級或甲二級打者，高位置擊球相較於習慣位置與中間位置有較慢的速度表現(擊球初速：28.09m/s<30.34m/s；最大棒頭合速度：27.65m/s<29.73m/s；最大骨盆角速度：578.80°/s<623.95°/s)。且在揮擊低球過程中有最大的肘關節角度；而在揮擊高球過程中則有最大的膝關節角度。結論：大專棒球打者在面對四種不同高度球情境時會有揮棒動作策略上與動作機制的差異；而在揮擊高球與低球的動作過程中差異最明顯；相較於甲二級打者，甲一級打者有較快的揮棒速度與擊球初速。Purpose : To realize the batting differences between two levels of baseball batters in four kinds of hitting height. Methods : Ten collegiate 1st level baseball players and ten collegiate 2nd level baseball players participated in this study. (22.85±2.37 years, 174.65±6.18 cm, 70.01±7.19 kg). A 3D motion analysis system (Vicon MX13+ Oxford Metrics Ltd., Oxford, England) and two force plates (40×60& 60×90 cm2, Kistler, Winterthur, Switzerland) were respectively used to collect human kinematic data and ground reaction force synchronously during batting. In order to calculate the ball speed by Kwon 3D software, a FASTEC high speed camera was use to take the image of ball. Nexus software was used to analyze the human kinematic and kinetic parameters of batters during batting. The differences between two levels and the differences among four hitting heights were tested by two-way mixed designANOVA. Significant level was set at α=.05 in this study. Results : The batters of 1st level revealed greater peak GRF in anterior-posterior direction (0.61BW>0.47BW), earlier appearing timing of peak GRF in anterior-posterior and vertical direction on fore foot (anterior-posterior direction: 68.81%<76.15% , vertical direction:71.35%<80.58%), faster speed of the bat head and faster ball exit velocity than batters of 2nd level (the maximum speed of the bat head:30.92m/s>27.37m/s , ball exit velocity:31.49m/s>27.74m/s). Batters of both levels revealed slower ball exit velocity, maximum speed of bat, maximum angular velocity of pelvis in high hitting position than accustomed hitting position and middle hitting position. Moreover, the elbow angle was the greatest at low hitting position, and the knee angles of both legs were the greatest at high hitting position. Conclusion : Collegiate baseball batters showed the difference in swing motion among four hitting heights, and the differences were larger between high and low hitting position. Furthermore, the batters of 1st level revealed faster swing speed and ball exit velocity.