Many people with fibromyalgia and other chronic pain conditions fear that activity will make their pain worse. But new research suggests they may be able to be more active than they think – without suffering from increased pain.

The study by researchers at the University of Michigan Health System and the Uniformed Services University of the Health Sciences in Bethesda, Md., found that fibromyalgia patients have similar average activity levels as people without those conditions. But it also found that their levels of high-intensity "peak" activities – such as bolting up the staircase, walking for several miles or taking an aerobics class – are much lower than among people without the condition.

The first-of-its-kind research – which involved round-the-clock activity monitoring and analysis rather than relying on patients self-reporting their activity levels – is helping researchers unlock some of the mysteries of fibromyalgia. The findings could lead to changes in the treatment of patients with the chronic condition of pain in the muscles and soft tissue, says Dan Clauw, M.D., director of the U-M Chronic Pain and Fatigue Research Center and professor of rheumatology at the U-M Medical School.

"When you ask people with fibromyalgia about their level of function in terms of activity levels, they'll report a lower function than almost any other group," says Clauw, senior author of the study, which appears in the current issue of Arthritis & Rheumatism. "The surprising thing that we found was that their average level of activity was about the same as someone who didn't have fibromyalgia."

But researchers found that patients in the study with fibromyalgia, chronic fatigue syndrome or both spent significantly less time in high-level activities compared to those without the conditions, the study reports.

The findings suggest that people with fibromyalgia self-report poor physical function and increased pain after activity because they think in terms of the most intense activities that cause higher levels of pain. But what they don't report – and possibly don't realize – is that they can sustain some level of activity without increased pain.

"We've probably been thinking about fibromyalgia incorrectly," Clauw says. "This group was impaired, but they weren't impaired in the way they thought they would be. This is good news for fibromyalgia patients."

The study used actigraphs, wristwatch-sized devices that measure movements in various directions (unlike a pedometer, which just measures movement in one direction). While previous studies have used actigraphs on fibromyalgia patients, this is the first study to perform complex, repeated-measures analyses of the results of ambulatory actigraphy and symptom reports.

The study involved 38 people with fibromyalgia, chronic fatigue syndrome or both conditions, and 27 age-matched people without those conditions.

Clauw hopes that the research will provide a new level of understanding of patients with these conditions. One possible outcome, he says, is a better insight into how much activity the patients can sustain without increased pain, based on information from evidence-based research rather than questionnaires.

"Exercise and activity are essential to the well-being of people with fibromyalgia," Clauw says. "Our research shows that higher activity is not in fact leading people to increased pain, and it could be used to show patients that they can be active."

Now, Clauw and his team at the U-M Chronic Pain and Fatigue Research Center are embarking on more studies of activity, exercise and pain among people with all kinds of chronic-pain conditions. They've started a registry of people who would be willing to take part in such studies, both those with chronic conditions and those without. For more information on the registry and the studies underway at U-M, visit www.med.umich.edu/painresearch