Pain-Related Brain Activity Evoked by Active and Dynamic Arm Movement: Delayed-Onset Muscle Soreness as a Promising Model for Studying Movement-Related Pain in Humans.

ObjectiveTo demonstrate delayed-onset muscle soreness (DOMS) is a suitable model for the study of movement-evoked pain, we attempted to identify brain regions specifically involved in pain evoked by active and dynamic movement under DOMS condition. SubjectTwelve healthy volunteers MethodsDOMS was induced in the left upper-arm flexor muscles by an eccentric elbow contraction exercise. Movement-evoked pain in the affected muscles was evaluated just before (day 0) and after (days 1-7 and 30) the exercise using a visual analog scale. Subjects underwent functional magnetic resonance imaging scans while performing repeated elbow flexion on day 2 (DOMS condition) and day 30 (painless condition). We compared brain activity between the DOMS and painless conditions. ResultsMovement-evoked pain reached peak intensity on day 2 and disappeared by day 30 in all subjects. No subject felt pain at rest on either of these days. Contralateral primary motor cortex (M1), parietal operculum and bilateral presupplementary motor area (pre-SMA) showed greater activity during active and dynamic arm movement with DOMS than during the same movement without pain. There was no difference in activation of brain regions known collectively as the pain matrix, except for the parietal operculum, between the two conditions. ConclusionActive and dynamic movement with pain selectively evoked activation of M1, pre-SMA, and parietal operculum, as assessed using DOMS. Our results demonstrate that DOMS is a promising experimental model for the study of movement-evoked pain in humans.