Musculature of the shoulder acts to accelerate, decelerate and stabilize the arm during throwing. Shoulder rotational strength profiles can be leveraged to identify deficits that may explain a change in performance and injury risk. Previous studies of professional baseball players have not distinguished strength profiles across geographic areas of origin, and often only consider pitchers.
PURPOSE: To characterize the effects of player position (Pitcher, Position Player) and geographic origin (North American, Latin American) on shoulder external (ER) and internal (IR) rotation strength in professional baseball players.
METHODS: Minor league baseball players (N = 242, N = 135 Pitchers, N = 162 North American) participated. Each athlete completed two trials of maximal isometric ER and IR strength (arm at 0° abduction) using a handheld dynamometer. Strength data were normalized to bodyweight.
RESULTS: Across both origins, position players were significantly stronger in ER (p < 0.001) and IR (p < 0.001) with higher ER:IR strength ratios (0.77 ± 0.17 vs. 0.73 ± 0.14, p < 0.043) compared to pitchers. Across all positions, Latin American athletes were significantly stronger in ER (mean difference (MD) = 0.3 N/kg, p < 0.001) and IR (MD = 0.2 N/kg, p < 0.001) compared to North American athletes. Specifically, Latin American pitchers were stronger in ER (MD = 0.4 N/kg, p = 0.002) and IR (MD = 0.2 N/kg, p = 0.006) compared to North American pitchers. No differences were found between position players of each region. North American pitchers were taller (189.3 cm ± 6.4 vs. 186.8 cm ± 5.6, p = 0.001) and heavier (94.6 kg ± 9.5 vs. 85.8 kg ± 13.4, p = 0.041) than Latin American pitchers. North American position players had similar heights but increased weight (89.1 kg ± 7.7 vs. 83.0 kg ± 11.5, p = 0.003) compared to Latin American position players.
CONCLUSION: Player position and geographic origin are related to shoulder rotational strength values in professional baseball players. Latin American pitchers were stronger than North American pitchers when strength was normalized to bodyweight. These normative values can be used to determine player deficits, declines in performance, targets for return to play after injury, and advance strength and conditioning practices. Supported by a Major League Baseball research grant.