Adding another incentive to exercise, scientists at Duke University Medical Center have found that physical activity improves arthritis symptoms even among obese mice that continue to chow down on a high-fat diet. The insight suggests that excess weight alone isn’t what causes the aches and pains of osteoarthritis, despite the long-held notion that carrying extra pounds strains the joints and leads to the inflammatory condition. Published Sept. 27, 2011 online in the journal Arthritis & Rheumatism, the findings are now being tested in people. “What’s surprising is that exercise, without substantial weight loss, can be beneficial to the joints,” said Farshid Guilak, Ph.D., professor of orthopaedic surgery at Duke and senior author of the study. “Ideally, it would be best to be fit and lose a little weight, but this shows that exercise alone can improve the health of your joints. This shows that if you are obese, it’s better to exercise,” Guilak said. “Sometimes pain can be a barrier to starting exercise, but if you overcome it, in the long term, it’s better.”