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Exercise Won't Make It Worse

The Problem For those with older or injured knees, it hasn't been clear if weight-bearing exercise helps or hurts. Some small studies have suggested it might protect against osteoarthritis (OA), perhaps by building cartilage; others have found the opposite. "There has been a lot of discordance and confusion in the literature about 'Can you?/Can't you?' " says David Johnson, an orthopedic surgeon and sports medicine specialist at Washington Hospital Center. Until now. According to a study in the journal Arthritis Care & Research, moderate exercise has no effect -- positive or negative -- on the development of OA in the knee, even for people who are overweight or obese....