A comparison of throwing arm kinetics and ball velocity in professional baseball pitchers with the fastest maximum joint and segment velocities

Abstract

Background: Significant associations have been established among individual maximum joint and segment velocities with throwing arm kinetics and ball velocity in baseball.

Methods: Professional (n = 338) pitchers threw 8-12 fastball pitches while evaluated with 3D-motion capture (480 Hz). Pitches (ideal and nonideal sequence order) were classified as 'High Velocity' for each segment/joint velocity subcategory or 'Population' with any pitch eligible for inclusion in multiple subcategories. Kinematic and kinetic parameters were compared among subgroups with post-hoc regression analysis.

Results: Population pitches in ideal sequence order (pitches: 71, pitchers: 19) had significantly faster ball velocity than population pitches in nonideal order (pitches: 3685, pitchers: 338) (39.0 ± 1.5 vs. 38.2 ± 2.2 m/s, respectively, P < .001). Irrespective of sequence, the lead knee extension velocity subgroup had faster ball velocity (38.9 ± 1.8 ms), compared to population (38.2 ± 2.2 m/s) (P < .001, d = 0.4). For nonideal sequence pitches, for every 1091°/s increase in maximum shoulder internal rotation velocity, shoulder superior force increased by 3.67% body weight (BW). Pitches in ideal order, for every 1414°/s in maximum shoulder internal rotation velocity, there was an increase in shoulder superior force by 4.29% BW, elbow medial force by 5.33% BW, and elbow distractive force by 9.33% BW.

Conclusion: Proper sequence order plays an important role in maximizing ball velocity with minimal implications for throwing arm kinetics. When throwing nonideal sequence, increasing maximum lead knee extension velocity positively impacts ball velocity, while increasing other velocities has negative implications on throwing arm kinetics.

Keywords: Fastball; biomechanics; elbow varus torque; kinematics; motion-capture; pitch.