A three-dimensional comparative study of the motions between speed throw and distance throw in the university baseball players

Abstract

The purpose of this study was to investigate the differences of the motions between the speed throw and the distance throw ， using a three − dimensiona1（ 3D ）motion analysis ． Twenty − four male university baseball players were the subjects of this study ． They were asked to throw a ba11 （ mass O， 144 kg）horizontally as fast as possible （ speed throw：ST ） ， and as far as possible （ distance throw ： DT ）． These motions were filmed by two high − speed video cameras ． 3D 且 andmark coordinates of the subiects and the bah were calculated by the DLT method ． The foUowing kinematic parameters were computed ：angle of release ， the component velocities of the baU， the 3D angles for the backward！ forward iean， right ！ left lean of the upPer torso， and the twist of the torso and those for the abduction ！ adduction ， horizonta1 且exion ！ extension ， intemal ！ external rotation at the shoulder joint ， and the 且exion ／ extension at the elbow joint of the throwing arm ． The sequential data were nor ・ malized with the time from the stride foot contact to the ball release ， and then averaged ． Angle of release was signi 盒cantly larger in the DT than in the ST ． Signi 且cant dif 驚 rence was not found betWeen the resUltant velocity of the ST and the DT ． Vertical velocity of the ball was sigriificant − lyぬrger in the DT than in the ST during the latter half of the acceieration phase ， On the other hand ， horizontal velocity of the ball was significantly larger in the ST than in the DT ． The backward lean and the left lean angles of the upper torso were also significantly larger in the DT than in the ST