Laird Harrison

May 22, 2015

PALM SPRINGS, California — Exercise activates brain centers associated with pain modulation in patients with fibromyalgia and may prove an effective treatment, researchers say.

"Acute exercise did result in a somewhat temporary improvement in centrally mediated pain modulation, and importantly this was without exacerbating pain symptoms," said Laura Ellingson, PhD, an assistant professor of kinesiology at Iowa State University, Ames.

Dr Ellingson presented the finding here at the American Pain Society (APS) 34th Annual Scientific Meeting.

Fibromyalgia is complex and largely unexplained, but abnormality in pain modulation is one of its hallmarks, Dr Ellingson said.

Understanding how this modulation plays out in the central nervous system could give some insights into the cause of the condition, she said.

Some previous studies have shown a decreased sensitivity to pain after exercise, while others have shown no effect or even an increase.

To examine this phenomenon, the researchers scanned the brains of 12 women with fibromyalgia by using functional MRI. The women's mean age was 39.5 years, and their mean Fibromyalgia Impact Questionnaire score was 52.9. The scale runs from 0 to 100 in order of increasing severity.

The researchers imaged the patients once immediately after they finished 25 minutes of moderate-intensity cycling on a stationary bicycle and once again a week later after quiet rest.

During this imaging, the participants rated the intensity and unpleasantness of painful heat stimuli on their left palms at 44°C, 46°C, and 48°C.

They scored both the pain intensity and unpleasantness of these stimuli about 2 points lower on a scale of 0 to 20 after exercise than after quiet rest.

The patients' fibromyalgia pain dropped by about 5 points on the McGill Pain Questionnaire Visual Analogue Scale after exercise. The scale runs from 0 to 100. Conversely, their pain increased by about 7 points after quiet rest.

The brain scans showed significantly greater activity in the patients' left anterior insulae after exercise than after rest as well.

"Exercise may function as a treatment via these temporary changes becoming more permanent over time," said Dr Ellingson.

The researchers would like to do more experiments of this kind, she said.

In the question-and-answer period that followed Dr Ellingson's presentation, one person in the audience asked whether the researchers were able to discern much variability among patients.

She responded that they had collected some information about how much the patients normally exercised but weren't able to reach conclusions about that. "We stayed away from looking too much at correlations with an n of 12," she said.

The study sheds some light on a difficult problem in pain management, said session moderator Benedict J. Kolber, PhD, research and education coordinator for the Chronic Pain Research Consortium at Duquesne University in Pittsburgh, Pennsylvania.

"Exercise is the best antidepressant and analgesic that's ever been invented," he said. "But these patients don't want to exercise. It hurts for them to move. That's the challenge. Eventually it won't hurt, but you have to get over that hump."

This study takes a step toward revealing how exercise might benefit these patients, he told Medscape Medical News.

"The fact that it combines the exercise intervention with the imaging is the power of this study," he said. "Ultimately as biologists we want to know why exercise is great," he said. "What is the mechanism behind it?"

Dr Ellingson and Dr Kolber have disclosed no relevant financial relationships.

American Pain Society (APS) 34th Annual Scientific Meeting. Presented May 13, 2015.

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