The muscle in fibromyalgia--a review of Swedish studies.

In Sweden, several studies have been performed in patients with fibromyalgia to study muscle morphology, chemistry and physiology in order to understand the origin of the most prominent symptoms in fibromyalgia: muscle pain, muscle fatigue and muscle stiffness. These studies have shown changes indicating disturbed microcirculation, mitochondrial damage and a reduced content of high energy phosphates. Thus, there may be an energy deficiency state in the resting painful muscle in fibromyalgia. Pain analysis has supported the idea that there is a nociceptive origin of the pain. Our hypothesis is that any condition that could lead to constant muscle hypoxia, e.g., through establishment of abnormal motor patterns, might be a possible cause of fibromyalgic pain.