Evidence that Swimming May Be Protective of Knee Osteoarthritis: Data from the Osteoarthritis Initiative.
Grace H Lo, Uzoh E Ikpeama, Jeffrey B Driban and 10 others
PMID 31628825WHAT IT FOUND
Knee pain was not lower in adults who reported swimming once other factors were considered, but they had less X-ray evidence of knee osteoarthritis, especially in young adulthood.
This shows association, not proof swimming prevents knee osteoarthritis.
Key findings
01Any history of swimming was associated with lower unadjusted frequent knee pain (37.2% vs 41.2%), but the adjusted difference was no longer statistically significant (36.4% vs 39.9%).
02History of swimming was associated with lower radiographic knee osteoarthritis prevalence (54.4% vs 60.3% unadjusted), and the adjusted trend remained significant, especially for swimming at ages 19 to 34.
03History of swimming was associated with lower symptomatic knee osteoarthritis prevalence (24.4% vs 29.5% unadjusted; 21.9% vs 27.0% adjusted), but the adjusted trend across swimming levels was not significant.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
Only 2,637 of 4,796 enrolled participants completed the activity survey, and non-completers were older, more often female, and more likely to have knee osteoarthritis, knee pain, knee replacement, or injury. Swimming exposure was self-reported retrospectively and only captured whether swimming was one of the top three activities in an age period, so frequency and duration were imprecise. The analysis is cross-sectional, so it cannot show that swimming came before knee osteoarthritis or that swimming caused the lower X-ray findings. Current advice to swim for arthritis may mean people with knee problems were more likely to swim, especially in older age periods; the authors addressed this by excluding the later age ranges from dose-response analyses. Total knee replacements were counted as frequent pain, radiographic osteoarthritis, and symptomatic osteoarthritis, which may mix surgical outcomes with disease prevalence. Some outcome data were imputed from earlier visits for 10% of participants.
Declared interests
The supplied article metadata says the work was supported by NIH extramural and non-U.S. government research. The supplied text does not include an author conflict-of-interest declaration.
The easy way to misread this
Do not tell patients that swimming has been proven to prevent knee osteoarthritis. This was an observational association, the adjusted knee pain result was null, and the authors call for prospective studies.