Glenohumeral and Hip Range-of-Motion and Strength Measures in Youth Baseball Athletes

Abstract

Context: The repetitive demands of throwing affect glenohumeral (GH) range of motion (ROM) and strength. Less is known about hip alterations in skeletally immature athletes. Objective: To compare GH and hip ROM and strength between age, position, and side of youth baseball athletes. Design: Cross-sectional study. Setting: Multicenter testing. Patients or Other Participants: Seventy-two healthy baseball athletes. Participants' self-reported characteristics were age group (7−11 years [n = 28] or 12−18 years [n = 44]), position (pitcher [n = 22], position player [n = 47], unreported [n = 3]), and side (throwing or nonthrowing arm, lead or stance leg). Main Outcome Measure(s): Bilateral GH and hip internal- and external-rotation ROM were measured passively and summed for total arc of motion (TAM). Glenohumeral and hip rotation and gluteus medius strength were measured. Analyses included linear mixed models. Results: Glenohumeral internal rotation was less in throwing than in nonthrowing arms (P < .05) except in younger pitchers (P = .86). Compared with older athletes, younger athletes had more GH external rotation (103.3° ± 7.7° versus 97.5° ± 9.4°; P = .002), TAM (156.4° ± 8.7° versus 147.9° ± 10.9°; P = .04), and external rotation in throwing compared with nonthrowing arms (101.9° ± 1.2° versus 97.9° ± 1.1°; P < .001). Glenohumeral TAM was less in throwing than in nonthrowing arms (150.5° ± 2.1° versus 154.9° ± 1.3°; P = .01). Younger athletes had more hip internal rotation (38.9° ± 6.8° versus 31.2° ± 7.5°; P < .001) and TAM (68.4° ± 10.0° versus 60.7° ± 9.8°; P = .001) than older athletes. Lead-leg hip internal-rotation ROM was greater than in the stance leg (34.8° ± 8.9° versus 32.8° ± 7.7°; P = .01). Overall, older players were stronger than younger players (P < .05), and the throwing arm was stronger in internal rotation than the nonthrowing arm (10.12 ± 3.72 lb [4.59 ± 1.69 kg] versus 9.43 ± 3.18 lb [4.28 ± 1.44 kg]; P = .047). Conclusions: Youth baseball athletes had typical GH ROM adaptations of less internal rotation and more external rotation in the throwing versus the nonthrowing arm. Greater ROM in younger athletes may be explained by prepubertal characteristics. We obtained hip-strength values in youth baseball athletes, and as expected, older athletes were stronger.