The Effect of Pitch Speed on Ground Reaction Forces in the Baseball Swing

• Main Authors: Lin, Chun-Lung, 林俊龍
• Other Authors: Chen, Ti-Yu
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/jqna55

碩士 === 國立彰化師範大學 === 運動學系 === 106 === In a baseball game, a good batter usually can be prominent by adjusting his swing mechanic to adapt different kinds of pitches. By analyzing ground reaction force (GRF), the adjustment mechanism of hitting movements can be investigated. The purpose of this study was to compare GRFs during swings against slow and fast pitches, furthermore, to resolve the adjustment mechanism of hitting different speed of pitches. 16 college baseball players stood on two force plates (Kistler, 1500Hz) and swung against fast pitches (127~133 km/hr) and slow pitches (107~113 km/hr) which were served by a pitching machine from 18.44m away. By using paired samples t-test, the peak and the timing of GRFs at different pitch’s speed could be explained. The result showed that 12 of these participants’ front foot GRFs in vertical and lateral direction existed a double peak pattern during swing phase, but other 4 participants showed a single peak pattern. The first peak in the double peaks pattern utilized to modulate the time of swing phase. In all results of GRFs analysis, only the rear foot GRF in directional component showed greater peak GRF value during swinging against the fast pitches(0.23±0.04BW) compared to slow pitches (0.21±0.04BW),and it occurred later for the fast pitches (0.30±0.18sec before the bat-ball contact) compared to slow pitches (0.42±0.18sec before the bat-ball contact). This led to the conclusion that a hitter’s rear foot played an important role in adjustment mechanism of hitting movements. Players were advised to spend more time on hitting practices against fast and the slow pitches. These would be helpful for players to be familiar with the swing mechanism of facing different speed of pitches.