Differences in the kinematics of the baseball swing between hitters of varying skill.

PURPOSE The aim of this study was to determine differences in bat swing kinematics in baseball hitters of varying ability. METHODS Kinematic data for the upper and lower body were collected from 20 trained male baseball players (22.3 ± 5.3 yr, 1.82 ± 0.07 m, 83.5 ± 10.9 kg), using three-dimensional computerized motion-analysis techniques. Participants were ranked before testing based on a novel coach's rating scale and seasonal batting average. They were subsequently separated into a relatively high-caliber group of hitters (n = 10) and a relatively low-caliber group of hitters (n = 10) for comparison. Importantly, the two groups were significantly different in terms of coach's rating (P < 0.01) and batting average (P < 0.05). RESULTS The results showed a significant difference in maximum bat swing velocity (P < 0.05) with high-caliber hitters having a higher velocity (36.8 m · s) in comparison with relatively low-caliber hitters (33.8 m · s). Lead elbow maximum angular velocity was significantly higher (35.9%) among relatively high-caliber hitters (P < 0.05). Angular velocity of the hip segment approached significance between the groups (P = 0.056). High-caliber hitters also had a right knee angle of 106° at ball contact, which was significantly (P < 0.05) higher than that of relatively low-caliber hitters (100°). There were no between-group differences for wrist and linear hip joint velocities at ball contact. CONCLUSIONS It was established that bat swing velocity is a key characteristic of the baseball swing when identifying skill level and performance between hitters. In addition, high-caliber hitters display greater lead elbow maximum angular velocity possibly because of achieving a higher angular hip segment velocity early in the swing. It is noted that although these attributes differentiate hitters of varying skill level, future research should examine whether developing these characteristics in players of lower ability improves batting performance.