Schematic illustration of the study design.

<p>The flow-chart shows the time-points (min) for the blood sample, assessments of pain intensity, fatigue, microdialysis and dialysate sampling as well as the brief work (consisting of repetitive dynamic contractions of the quadriceps muscle) in 32 female patients with fibromyalgia and 32 healthy, pain-free age-matched controls. The pain intensity was assessed on a visual analogue scale (VAS; 0–100) while fatigue was assessed with Borg’s Rating of Perceived Exertion (RPE) Scale before, during and after the brief work.