Muscle fiber velocity and electromyographic signs of fatigue in fibromyalgia.

Introduction: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls.

Methods: sEMG was performed on the biceps brachii muscle of 13 women with FM and 14 matched healthy controls during prolonged dynamic exercises, unloaded, and loaded up to 20% of maximum voluntary contraction.