Association Between Pelvic Motion and Hand Velocity in College-Aged Baseball Pitchers

Previous research suggests that pelvic motion is closely related to pitching performance over the course of a season. Few studies have examined pelvic motion and its relationship to an acute pitching variable. Therefore, the purpose of this study was to investigate the relationship between pelvic motion and hand velocity in college-aged pitchers. Nine healthy club baseball team pitchers performed two tests: A pelvic motion test, and a hand velocity test during a pitch. The pelvic motion test required participants to lift their kicking leg 10 cm off the ground, then hold that position for two seconds before returning to a double leg stance. This procedure was repeated five times. The hand velocity test required participants to perform five maximal-effort pitches thrown from a wind-up position. Motion of the pelvis and hand during the tests was recorded with a passive infrared marker-based motion analysis system (Vicon). Angular displacements (tilts) of the pelvis and peak hand velocity were computed from coordinate data using Nexus software (Vicon). Given the low sample size, ninety-nine percent confidence intervals were used to interpret the correlation (Pearson’s r) between pelvic motion and hand velocity. The intervals were computed using the bootstrap procedure (n=100). Based on ninety-nine percent confidence intervals, we observed a negative correlation between anterior-posterior pelvic tilt and hand velocity (99% CI: -0.45 \u3c r \u3c -0.64) and a positive correlation between medial-lateral pelvic tilt and hand velocity (99% CI: 0.29 \u3c r \u3c 0.53). These data imply that pelvic motion in the sagittal plane is associated with a decrease in hand velocity, while motion in the frontal plane is associated with an increase in hand velocity. Medial-lateral pelvic motion occurs in the same plane as the pitch itself, which could contribute to the overall effectiveness of the kinetic chain in the pitching motion, thus creating a faster pitch