Shoulder pain and injury risk factors in competitive swimmers: A systematic review.

Shoulder pain is common among competitive swimmers, and coaches and clinicians have long wondered which training or physical factors actually raise the risk. This systematic review pulled together cohort, cross-sectional, and case-control studies to see what the evidence says about 80 different possible risk factors, from training volume to joint range of motion to muscle strength. The overall picture was underwhelming: for most variables, the evidence was too limited or inconsistent to draw firm conclusions. A few factors showed moderate evidence of an association, including competitive level and patterns of shoulder muscle activity, while others, like range of motion, training frequency, stroke specialty, height, sex, and age, showed moderate evidence against being linked to injury.

One single study of better quality suggested that rapid increases in training load and weaker shoulder strength endurance might matter, but this rests on one dataset. The main limitation is the overall scarcity of high-quality research, meaning most risk factor claims in swimming shoulder injury remain uncertain.

If you're a competitive swimmer who's dealt with shoulder pain, you've probably heard theories about what causes it, maybe it's your stroke technique, your flexibility, or how much you train. This review looked at all the existing research testing these ideas to see which ones actually hold up. The honest answer is that for most factors researchers have studied, there simply isn't enough good evidence to say they clearly raise or lower shoulder injury risk.

A couple of things showed a possible link, like a swimmer's competitive level and certain patterns of shoulder muscle activity, while things like flexibility, training frequency, stroke type, height, sex, and age didn't show a consistent connection. One stronger study suggested that sudden jumps in training load and weaker shoulder endurance strength might be relevant, but this comes from just one piece of research.

Overall, the science on swimmer's shoulder risk factors is still thin, so these findings should be seen as early clues rather than settled answers.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

For clinicians working with competitive swimmers, this review addresses a common question in practice: which modifiable factors, if any, should inform assessment or monitoring of shoulder pain risk. The findings are sobering rather than clarifying.

Across 22 studies and 80 variables, most showed either limited or conflicting evidence, meaning the broad assumptions often made about range of motion, training frequency, stroke specialty, or anthropometric factors as risk markers are not well supported one way or the other by the current literature. The more informative signals were moderate-evidence associations between a swimmer's competitive level (direction not specified) and shoulder pain, and between pain and altered shoulder muscle recruitment, such as increased serratus anterior activity, though these remain associative rather than causal. The single highest-quality study in the review (n=201) linked a high acute-to-chronic workload ratio and reduced posterior shoulder strength endurance to injury, raising shoulder strength-endurance as a plausible modifiable target worth further prospective investigation, though this rests on one study and cannot be generalized confidently.

The review does not establish causal mechanisms or justify specific screening or intervention protocols; it mainly highlights how sparse and heterogeneous the evidence base is, and that future prospective research re-examining established risk factors is needed before clinical recommendations can be made with confidence.