Does an Increase in Supraspinatus Tendon Thickness After Swimming Increase the Likelihood of Future Shoulder Pain?

Background: Increase in supraspinatus tendon thickness (STT) resulting from swimming practice has been observed in those with a history of shoulder pain. The magnitude of change in STT after a swimming session and its rate of recovery may be an indicator of future shoulder pain incidence.

Hypothesis: The supraspinatus tendons that demonstrate a greater increase in thickness as a result of swimming practice will have an increased likelihood of future shoulder pain in a cohort of competitive swimmers over a period of 6 months.

Design: Descriptive epidemiology study.

Level of evidence: Level 2b, individual cohort studies.

Methods: A cohort of 50 nationally qualified swimmers aged between 14 and 22 years, from 3 open National Swimming Programs in Victoria, Australia, were recruited for this study. Ultrasonographic measurements of swimmers' STT was obtained of both shoulders, before, immediately after, and 6 hours after a single swimming practice session. Data were recorded of any significant interfering shoulder pain at 3 and 6 months after the initial testing session.

Results: Stepwise logistic regression models indicated that significant predictors of the likelihood of experiencing significant interfering pain were sex [significant at 6 months; odds ratio (OR) 4.2] and the extent of change in STT immediately (OR 2.3 and 1.3 per mm at 3 and 6 months, respectively) and 6 hours postpractice (OR 1.9 and 1.5 per mm at 3 and 6 months, respectively).

Conclusion: The current data suggest larger increases in tendon thickness after training are associated with an increased likelihood of future shoulder pain.

Clinical relevance: These data may be valuable for monitoring training load and identifying athletes who may have an increased likelihood of shoulder pain.