棒球投手等速肌力與揮臂速度對投擲不同重量棒球之投球影響

Purpose: to investigated correlation among isokinetic force, throwing arm velocity, pitching initial velocity, and pitching ending velocity. To comparison between pitchers of different isokinetic force characteristics and between pitchers of different throwing-arm velocity. To compare the throwing of various weighted baseballs. Method: Six elite pitchers measured isokinetic force by using Biodex System, and filmed by using Motion Analysis System at 250Hz when they threw randomly 50g, 75g, 100g, 125g, 150g, 175g, 200g, 225g, 250g, 275g, 300g baseballs. Results: (1) There was significant negative correlation between force quantity and force balance (p＜.05, r=-.86). Throwing-arm velocity had significant correlation with pitching initial velocity (p＜.05, r=.77). (2) Pitchers with better force balance had faster pitching ending velocity than those with force quantity (t=-2.449, p=.04). (3) Pitchers with different throwing-arm velocity had similar isokinetic performance and pitching velocity (p＞.05). (4) Throwing-arm velocity, pitching initial velocity, and pitching ending velocity were decreased with increasing baseball weight. (5) 100g-125g baseballs produced the fastest throwing-arm velocity and pitching velocity for pitchers with force quantity, and their arm trajectory had more deviation during throwing different weighted baseballs. In contrast, 50g-75g baseballs produced the fastest throwing-arm velocity and pitching velocity for pitchers with force balance, and their arm trajectory were lower deviation. Conclusion: Pitchers should pay more attention to both force balance and force increase. For this reason of increasing throwing-arm velocity and pitching velocity, 50g-75g and 100g-125g baseballs were more suitable weights for pitchers with force balance and with force quantity, respectively. 50g-75g were proper weights for evaluating pitchers ability.