In a study that came out yesterday, researchers at Duke University have discovered that exercise eases arthritis, even among the obese. One detail â€“ the study was done with mice. But based on the positive outcomes, the findings are now being tested on people.
With Farshid Guilak, professor of orthopedic surgery at Duke and a senior author of the study, the team of scientists found that physical activity has a positive effect of arthritis symptoms, even among obese mice that continued to eat a high-fat diet. â€œWhatâ€™s surprising is that exercise, without substantial weight loss, can be beneficial to the joints,â€ stated Dr. Guilak. â€œIdeally, 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.â€
According to the Arthritis Foundation, 20% of adults in the U.S. have been diagnosed with arthritis, at an annual cost of $128 billion, so if the findings are similar with people, even modest improvements will be significant.
In the study, the researchers split the mice into two groups: 50% had a high-fat diet and 50% were fed a regular diet. Very quickly, the high-fat mice gained weights, had a decrease in their ability to process glucose, and had much higher blood levels of the molecules that trigger the chronic inflammation thatâ€™s associated with osteoarthritis (disease characterized by degeneration of cartilage and its underlying bone within a joint as well as bony overgrowth. The breakdown of these tissues eventually leads to pain and joint stiffness).
Since so many cases of arthritis are associated with inactivity and obesity, the researchers wanted to discover whether a high-fat diet would induce knee osteoarthritis, then determine whether or not exercise would provide a protective effect. What they found was surprising â€“ if the extra weight on the joints had been the cause of the arthritis, exercise would have exacerbated the symptoms. But the exercise actually helped, affecting some of the assumptions about the relationship between physical activity and obesity!
â€œEven though there was the same amount of body fat, the fat was different,â€ stated Dr. Timothy Griffin, the lead author of the study. Even though the fat cells were still producing the inflammatory molecules that are associated with arthritis, they were not â€œturned onâ€ in a way to trigger the inflammation. â€œI donâ€™t want to say exercise is turning off that inflammatory signal; it just impairs it,â€ remarked Griffin.
The conclusion that can be inferred from this study is that exercise is beneficial, even for obese people who suffer from arthritis pain. Once the findings have been replicated or confirmed on humans, exercise for obese arthritis sufferers may become a standard prescription!
- Published Sep. 27, 2011 online in the journal Arthritis & Rheumatism. The study was supported by grants from the National Institutes of Health and the Arthritis Foundation.