Inter-relations between clinical parameters and muscle function in patients with primary fibromyalgia.

In forty-four female patients with primary fibromyalgia, muscle function was related to clinical parameters such as age, height, number of tenderpoints, subjective scores of physical capacity and number of subjective symptoms. Muscle function was determined as the dynamic muscle strength measured with an isokinetic dynamometer. Muscle function was found to be low in primary fibromyalgia patients with pronounced muscle tenderness compared to matched controls. Furthermore the reduction in muscle function increased with increasing number of tenderpoints and subjective symptoms. In primary fibromyalgia patients correlations between muscle strength and age/height were either not present or were weaker than in the control subjects. It is concluded that voluntary dynamic muscle strength is a useful parameter for measuring disease impact in primary fibromyalgia patients.