NEW YORK (Reuters Health) - To help guard against the pain syndrome fibromyalgia, best to maintain a healthy weight and stay active, according to a new study from Norway.

The study in women found that being overweight or obese was associated with increased risk of fibromyalgia, especially among women who weren't all that physically active.

It is well established that maintaining a healthy lifestyle, including staying fit, trim and active helps prevent several chronic conditions such as heart disease and high blood pressure, Paul J. Mork, who led the study, noted in an email to Reuters Health.

"Our study indicates that a similar association also exists for development of" fibromyalgia," writes Mork, from the Human Movement Science Program, Norwegian University of Science and Technology in Trondheim.

Fibromyalgia is a debilitating pain syndrome that affects an estimated 2 to 4 percent of the population. It's characterized by chronic pain, often in the neck, shoulders, back, hips, arms and legs. Fatigue, depressed mood, and difficulty thinking and sleeping are other common symptoms. There is no clear-cut cause.

Mork said while an association between fibromyalgia and being overweight or obese has been shown in prior "cross-sectional" studies, his is the first forward looking, or "prospective" study to document being overweight or obese as independently raising one's risk of developing the pain syndrome.

The findings, published in the journal Arthritis Care and Research, are based on nearly 16,000 physically able, fibromyalgia-free women who were followed for 11 years. During this time, 380 developed fibromyalgia.

Overweight and obese women had a 60 percent to 70 percent higher risk of developing fibromyalgia over the study period, relative to their normal-weight counterparts, the researchers found.

They also found that women who said they exercised 4 or more times a week had a 29 percent lower risk of developing fibromyalgia compared to inactive women. A look at the number of hours exercised each week revealed that women who said they got 2 or more hours a week had a 23 percent lower risk of the pain syndrome.

In looking at the combined effects of exercise and body weight on risk of fibromyalgia, the researchers found a greater than two-fold increased risk for overweight or obese women who were either inactive or who reported exercising for 1 hour or less each week. There was no clear relationship between exercise and risk of fibromyalgia in normal-weight women.

Overall, this study found a "weak protective" effect of leisure time physical activity on future development of fibromyalgia, Mork noted. "This was somewhat unexpected and needs further exploration," he admitted.

However, Mork said it's important to note that his team was not able to differentiate between different types of exercise "and it might be possible that some exercise types are more beneficial than others in protecting against future development of fibromyalgia."

He and his colleagues conclude, based on their study and others, that maintaining a healthy weight and regular exercise are important for reducing the risk of fibromyalgia.

SOURCE: Arthritis Care and Research, May 2010.