Resumen de Adolescent Baseball Pitching Technique: A Detailed Three-Dimensional Biomechanical Analysis
Carl W. Nissen, Melany Westwell, Sylvia Ounpuu
Purpose: Document the biomechanics of the pitching motion to help provide insight about the etiology of common injuries seen in adolescent baseball pitchers.
Methods: Kinematic and kinetic data for the upper and lower extremities, thorax, and pelvis were collected from 24 adolescent pitchers, using modern three-dimensional computerized motion-analysis techniques.
Results: Original information regarding forearm and wrist motion was reported in this study and were consistent with expected motions for the fastball pitch. Average excursion of motion was: pronation/supination 63 ± 15°, wrist flexion/extension 44 ± 14°, and ulnar/radial deviation 12 ± 4°. Explosive forearm motion occurred between ball release (BR) and maximal glenohumeral internal rotation (GH-MIR) with a peak pronation velocity of 2051 ± 646°·s-1. The majority of internal/external and abduction/adduction shoulder motion was attributed to the glenohumeral motion. Internal glenohumeral rotation range of motion was 125 ± 13° and mean peak internal glenohumeral rotation velocity was 3343 ± 453°·s-1. Thorax and pelvic motion peak velocities and accelerations occurred before the peak elbow varus moment, which occurred at 59% of the pitch cycle (PC). The peak shoulder, elbow, and wrist velocities and accelerations occurred after the peak elbow varus moment. The pelvis squared to the plate at 51 ± 10% PC and the thorax at 59 ± 7% PC with maximal glenohumeral external rotation (GH-MER) at 65% PC and BR at 78 ± 3% PC. The data collected in this study were consistent with the literature, with the exception of joint velocities and moments, which were lower than those in one published study.
Conclusion: We have established the kinematic and kinetic parameters of the adolescent baseball pitch. These measured parameters and the differences between adolescent pitchers and their adult counterparts can be used to examine and help determine the causes of the rapid increase in adolescent pitching injuries
