Shoulder weakness in professional baseball pitchers.

The purposes of this study were to: 1) compare shoulder range of motion and strength in professional baseball pitchers (N = 47) compared with age-matched controls (N = 16), and 2) examine the relationship of injury history to strength and range of motion. Based on injury history pitchers were categorized as: 1) none (N = 26), 2) injury requiring conservative intervention (N = 9), or 3) injury requiring surgical intervention (N = 12). Range of motion was measured for internal rotation (IROM) and external rotation (EROM). Eccentric strength was measured by hand-held dynamometer for internal rotation (IR), external rotation (ER), abduction (ABD), and supraspinatus muscle (SUP) strength. Injury history had no effect on strength and range of motion. Dominant EROM was greater in pitchers, P < 0.0001, and controls, P < 0.05, with pitchers having greater EROM motion bilaterally, P < 0.0001. Pitchers were weaker in SUP on the dominant vs nondominant side, P < 0.0001, and on the dominant side for weight adjusted ER, ABD, P < 0.01, and SUP, P < 0.0001, compared with controls. In conclusion, dominance and pitching resulted in soft tissue adaptation. Pitchers displayed weakness in three of four tests by comparison with controls, suggesting that the demands of pitching are insufficient to produce eccentric strength gains and may in fact lead to weakness. Dominant-side SUP weakness in pitchers may reflect subclinical pathology or chronic fatigue.