Risk Factors Associated with New Onset of Shoulder Pain and Injury Among the Athletic Population: A Systematic Review of the Literature.

All 19 studies defined shoulder pain or injury differently, covering location, time missed, whether care was sought or a specific questionnaire, so the authors could not pool the numbers and could only describe the findings in words. How risk factors were measured was not consistent: strength was tested with hand-held dynamometers in some studies and isokinetic devices in others, and reported as ratios, scaled to body weight, or as raw strength. How many athletes dropped out was the main reason studies were not rated at low risk of bias, and three studies were rated high on that element. In some studies it was not clear whether athletes were free of pain at the start, because pain and injury were defined so variably. Only studies published in English were kept, and the inclusion criteria were restrictive. Eighteen of the 19 studies simply followed athletes and watched what happened, so they show who got injured, not whether changing a measured factor prevents injury.

The authors report no conflicts of interest. The review was registered in advance on PROSPERO (CRD42020187086).

Do not read these risk factors as treatment targets that will prevent injury if you change them. Eighteen of the 19 studies only followed athletes and watched what happened, so they can show who got hurt but not whether stretching, strengthening or load management changes anything. The single randomised trial tested a whole shoulder prevention programme in handball players, so no individual test or exercise can be credited for that result.