Comparisons between American and Korean Professional Baseball Pitchers

Escamilla R, Fleisig F, Barrentine S, Andrews J, Moorman C. Kinematic and kinetic comparisons between American and Korean professional baseball pitchers. Sports Biomechanics 1(2):213-228, 2002.

Methods

Researchers from ASMI studied kinematic (velocities and angles), kinetic (forces and torques), and temporal (timing) differences between 11 American and 8 Korean professional baseball pitchers. These 19 healthy pitchers threw fastball pitches from an indoor mound toward a home plate, which was placed 18.4m (regulation distance) away. Four electronically synchronized high-speed (200 frames per second) cameras captured each of these pitches and created a three dimensional digital model for statistical analysis. A radar gun was used to measure ball velocity. Twenty-seven parameters were analyzed at various stages of the pitching motion.

Results

The 27 parameters were evaluated at lead foot contact (after the stride), during arm cocking, during arm acceleration, at ball release, and during arm deceleration. At lead foot contact, the researchers found that American pitchers horizontally abducted their throwing shoulder more than Korean pitchers. Korean pitchers tended to have a greater amount of shoulder abduction and external rotation at lead foot contact. During arm cocking however, American pitchers had significantly more shoulder external rotation and greater maximum pelvis angular velocity. At ball release, American pitchers displayed more forward trunk tilt and less lead knee flexion. Additionally, American pitchers threw the ball with 10% greater velocity. This may be due to the findings that the American pitchers had greater shoulder external rotation during arm cocking, and greater forward trunk tilt at ball release. Both these parameters have been associated with increased ball velocity in previous studies.

In the kinetic study, American pitchers had significantly greater maximum shoulder internal rotation torque and maximum elbow varus torque during arm cocking. Additionally, American pitchers had significantly greater elbow flexion torque during arm acceleration, and significantly greater shoulder and elbow proximal forces during arm deceleration.

The greater angles, velocities, forces, and torques found to be present in American pitchers when compared to Korean pitchers help create greater ball velocities. However, these differences are also the factors that create greater risks for shoulder and elbow injury.