The study also showed that more frequent exercise is better than less. Three supervised sessions per week provided more benefits than two sessions. But while doing aerobic exercise more often boosted the benefits, increasing the intensity didn’t seem to. When it came to strength training, routines that focused on strengthening the quadriceps (the large group of muscles in the upper leg) were more effective than those that focused on the legs in general.

The study findings support some previous analyses, says Kelli D. Allen, PhD, associate research professor at Duke University Medical Center and Durham VA Medical Center. “Prior meta-analyses and systematic reviews … suggest that both aerobic and strength training are beneficial for reducing pain and disability in knee OA,” says Allen. “One prior meta-analysis did an indirect comparison of aerobic walking and quadriceps strengthening exercises and found no apparent differences in their effects on pain and functioning. Those findings agree with this new meta-analysis that, overall, the effects of aerobic and strengthening exercises on pain and function seem to be similar for people with knee OA.”

Some previous analyses have also come to similar conclusions about mixing different types of exercise, though more study is still needed. “Although this finding about mixed exercise programs for knee OA has been suggested by other recent systematic reviews, a ‘gold standard’ type of study to test this finding would be a randomized trial where patients are assigned to either a single type of training or mixed training, with all other aspects of the program – such as dose, duration and intensity – being equal for the two groups,” says Allen.

“It is certainly possible that mixed exercise, for some reason, is not as effective as focusing on either aerobic or strengthening exercise alone,” she adds. “However, it’s also possible that some other aspects of the mixed exercise programs in this meta-analysis [for example, duration or supervision] resulted in lower effectiveness than the studies that focused on single interventions.”

One message is clear: Exercise helps. “I think [the analysis] reinforces the idea that physical activity is good for people with osteoarthritis, and that both strength exercises and aerobic activities are beneficial and not harmful,” says Callahan.

The best exercise of all may be the one that you’re willing to do, and keep doing. “Different people choose or feel better doing certain things,” she says. “We always recommend to choose an activity that you like and one where you don’t have worse pain two hours after you do it.” The key is to do something rather than nothing. “Any physical activity and movement at all is going to be better than no activity.”