Good news for patients at risk for osteoarthritis, or OA – there’s new evidence that physical activity can help prevent knee OA by maintaining cartilage, which keeps your joints healthy.

Researchers from Monash University in Melbourne, Australia ,discovered that while exercise increases bone spurs, or osteophytes, those same bony growths may not be bad for cartilage in knees with osteoarthritis as previously thought. Instead, bone spurs may help the knee adapt to the loads and forces that come with physical activity – so physical activity is good for knee OA, say the researchers.

The researchers reviewed 28 studies involving nearly 10,000 patients for the study, which was published in the American College of Sports Medicine journal, Medicine & Science in Sports & Exercise.

Previous studies that suggested physical activity was bad for knees were too reliant on using bone spurs to define whether a subject had OA, says study author Flavia Cicuttini, PhD, head of Monash University’s Musculoskeletal Unit in the Department of Epidemiology and Preventive Medicine. “The emerging results suggest that the important part of the joint to look at is the joint cartilage and the effect physical activity has on that rather than solely looking at osteophytes.”

Until recently, bone spurs were examined through X-rays. “Now that we are able to more accurately measure joint cartilage using MRI, and not just indirectly using joint space width (as with X-rays), we can directly look at the relationships between cartilage and physical activity,” adds co-author and senior research fellow Donna Urquhart, PhD. “What we are now seeing is that there is a beneficial effect of physical activity on joint cartilage.“

“In my practice, I’m sharing the concept that exercise is good when done within tolerance. I ask the patient to listen to what their knee is telling them – what it will allow them to do. Take it to that limit but not beyond,” explains Jonathan Chang, MD, a clinical associate professor of orthopaedic surgery at the University of Southern California in Los Angeles. Dr. Chang says the study adds to a growing body of evidence suggesting that exercise is beneficial to joints.

“Exercise is good. But exercise intelligently,” agrees Bashir Zikria, MD, an assistant professor of sports medicine at Johns Hopkins University Medical Center in Baltimore. Low-impact exercises, like walking, cycling or using an elliptical machine are smart choices, says Dr. Zikria. If you run, play basketball or do other high-impact activities, avoid hard surfaces and don’t do it every day.

Dr. Chang also says if patients with arthritis aren’t currently exercising, they should talk with their physician first before they lace up their athletic shoes for the first time.

“Mild to moderate exercise has been shown in multiple studies to be beneficial, even when you have arthritis. But that has to be individualized,” Dr. Chang says. “Everyone’s circumstances differ. So having a good discussion with your physician would be important.”