Background/Hypothesis: Shoulder pain in elite swimmers is common and its pathogenesis is uncertain.
Hypothesis/Study Design: We used a cross-sectional study design to test Jobe’s hypothesis that repetitive forceful swimming leads to shoulder laxity which in turn leads to impingement pain.
Methods: Eighty young elite swimmers (13-25 years of age) completed questionnaires on their swimming training, pain, and shoulder function. They were given a standardized clinical shoulder examination, and tested for glenohumeral joint laxity using a non-invasive electronic laxometer. 52/80 swimmers also attended for shoulder magnetic resonance imaging (MRI).
Results: 73/80 (91%) swimmers reported shoulder pain. Most (84%) had a positive impingement sign and 69% of those examined with MRI had supraspinatus tendinopathy. The impingement sign and MRI-determined supraspinatus tendinopathy correlated strongly (rs=0.49, p<0.00001). Increased tendon thickness correlated with supraspinatus tendinopathy (rs=0.37, p<0.01). Laxity correlated weakly with impingement pain (rs=0.23, p<0.05) and was not associated with supraspinatus tendinopathy (rs=0.14, p=0.32). The number of hours swum/week (rs=0.39, p<0.005) and weekly mileage (rs=0.34, p=0.01) both correlated significantly with supraspinatus tendinopathy. Swimming stroke preference did not.
Conclusions: These data indicate: (1) supraspinatus tendinopathy is the major cause of shoulder pain in elite swimmers; (2) this tendinopathy is induced by large amounts of swimming training; and (3) shoulder laxity per se has only a minimal association with shoulder impingement in elite swimmers. These findings are consistent with animal and tissue culture findings which support an alternate hypothesis: the intensity and duration of load to tendon fibers and cells causes tendinopathy, impingement, and shoulder pain.