Background: A high prevalence of throwing-related shoulder and elbow pain has been documented in adolescent baseball pitchers.
Hypothesis: Pitchers with a history of throwing-related pain will have weakened dominant-arm posterior shoulder musculature and greater dominant-arm glenohumeral total range of motion (ROM) loss compared with pitchers without throwing-related pain.
Study design: Controlled laboratory study.
Methods: Twenty-three adolescent pitchers (age 15.7 +/- 1.4 years) were tested. Twelve pitchers had throwing-related pain in the prior season and were currently symptom-free, while the remaining 11 pitchers had no such history of pain. Internal and external rotation ROM and muscle strength (lower trapezius, middle trapezius, rhomboids, latissimus dorsi, supraspinatus, internal rotators, external rotators) were measured bilaterally. Dominant versus nondominant differences in ROM and strength were compared between pitchers with and without throwing-related pain.
Results: As a whole, the group of 23 pitchers had a loss of internal rotation ROM (13 degrees +/- 10 degrees , P < .001) and gain in external rotation ROM (11 degrees +/- 10 degrees , P < .001) on the dominant versus nondominant arm, with no effect on total ROM (2 degrees +/- 7 degrees loss, P = .14). There was no difference in bilateral comparison of total ROM between pitchers with and without throwing-related pain. Dominant versus nondominant muscle strength was lower (P < .05) for the pain group versus nonpain group for the middle trapezius (7% +/- 19% vs 22% +/- 12%) and supraspinatus (-4% +/- 27% vs 14% +/- 14%) and higher (P < .05) for the internal rotators (19% +/- 14% vs 6% +/- 12%).
Conclusion: Throwing-related pain in this population may be due to the inability of weakened posterior shoulder musculature to tolerate stress imparted on it by adaptively strengthened propulsive muscles.
Clinical relevance: Selective posterior shoulder strengthening may be indicated in rehabilitative and injury prevention programs for adolescent pitchers.