Biomechanical characteristics of sidearm and underhand baseball pitching: Comparison with those of overhand and three-quarter-hand pitching

Abstract

Many studies of baseball pitching have been conducted, but few of have focused on the sidearm and underhand pitching styles. To describe kinematic and kinetic characteristics of sidearm and underhand baseball pitching, four professional pitchers (two for sidearm, two for underhand) and a comparison group of thirteen overhand and three-quarter-hand pitchers were videotaped with the use of two high-speed cameras (200 Hz)_. After a small reliability study, the fastest throws that struck the strike was chosen for analyses. An inverse dynamic approach was used to determine joint kinetics of the upper extremity. If both data from a particular group were more than one standard deviation from the comparison mean, then it was assumed that there was a trend towards the data being different from the comparison group. The underhand pitchers bent their trunks to the throwing arm side and the sidearm pitchers kept their trunk relatively erect. The underhand pitchers abducted their shoulders lower than 75 degrees during the arm acceleration phase and the sidearm pitchers kept their shoulder perpendicular to the trunk. Maximum elbow medial forces for the sidehand pitchers and maximum shoulder anterior forces for the underhand pitchers were greater than the comparison group. Maximum shoulder horizontal adduction torques for the underhand pitchers were less than the comparison group. The sidearm pitching and the underhand pitching had different kinematic and kinetic characteristics from the overhand and three-quarter-hand pitching. The knowledge from the previous studies should not be always applied to these pitching styles.