The finding isn’t likely to sway Katie Ledecky or other swimmers from training for the 2020 Summer Olympics in Tokyo, but a small study at Henry Ford Health System in Detroit has shown that long competitive careers in the pool can saddle these athletes with chronically reduced mechanical properties in muscles and tendons of the shoulder, heightening the likelihood of rotator cuff damage.

The authors published their findings online Aug. 22 in Sports Health.

Jack Dischler, BS, Michael Bey, PhD, and colleagues enrolled 18 collegiate female swimmers. The researchers used standard musculoskeletal ultrasound to assess tendinosis, shear wave elastography ultrasound to assess the status of the supraspinatus muscle, athletes’ self-reported pain and function levels, and other measures.

Using linear regression to assess the association between years of competition and outcome measures, they found competitive years positively associated with tendon thickness and negatively associated with shear wave velocity pain/function scores.

There was no association between years of competition and shoulder strength.

“Long-term competitive swim training is associated with declining measures of supraspinatus muscle/tendon properties and self-reported measures of pain and function,” the authors write. “Although specific injury mechanisms are still not fully understood, these findings lend additional insight into the development of rotator cuff pathology in swimmers.”