Just about any exercise is good, but for people at risk for osteoarthritis (OA), light exercise such as walking might be best, according to new research.

University of California, San Francisco (UCSF) researchers studied 133 individuals with OA risk factors who took part in the Osteoarthritis Initiative Study, a nationwide research study sponsored by the National Institutes of Health. The study’s goal was to better understand how to prevent and treat knee osteoarthritis.

Participants were grouped by the level of their exercise regimen – strenuous, light or none. The researchers conducted MRI scans of their knees. The images revealed:

  • Those who did light exercise, such as walking, more than three days a week for less than two hours per day had the healthiest knee cartilage.
  • Those who did high-impact, strenuous exercise, such as running, skiing or playing squash, for more than an hour a day at least three times a week had degenerating cartilage, which increases the risk of developing OA.
  • Those who didn’t exercise at all also showed signs of more degenerated, less healthy cartilage.

Don't Overdo It

In addition to these findings, presented at the 2010 meeting of the Radiological Society of North America in Chicago, researchers linked the degeneration of knee cartilage to frequent, deep knee bending – activities such as squatting for more than 30 minutes a day or climbing more than 10 flights of stairs a day.

“The take-home message is you should do exercise. It’s critical to keep the cartilage healthy, but you should not overdo it or perform risky sports,” says senior author Thomas M. Link, MD, professor of radiology and chief of musculoskeletal imaging at UCSF.

The good news is you don’t have to start training for triathlons. Link recommends three to four days a week, 30 to 60 minutes at a time of walking, hiking, bicycling, swimming or using an elliptical trainer.