Reorganized Motor Control Due to Muscle Pain

Abstract

It has become evident that muscle pain interferes with motor control strategies, and different patterns of interaction are reported during rest, static contractions, and dynamic conditions. A reorganized motor control system with functional adaptations of the muscle coordination and strategies is a key factor in musculoskeletal pain conditions; its relevance in the transition from acute pain to chronic pain is most likely underestimated. The interaction between muscle pain and motor control depends on the specific motor task. Muscle pain causes no increase in muscle activity assessed by electromyography at rest, reduces maximal voluntary contraction (MVC) levels, and shortens endurance time during submaximal contractions. Moreover, muscle pain causes an adaptive change in the coordination during dynamic exercises. In some cases, increased muscle activity reflecting reorganized muscle coordination and strategy is also a component of the functional adaptation to muscle pain. In general, the “vicious cycle” hypothesis is not supported by these findings. More relevant is an adaptive model predicting reduced agonistic muscle activity eventually advanced by changed antagonistic muscle activity. The quantitative motor control assessment procedures provide additional clinical information, and give further support for optimizing prevention procedures and treatment regimes and for musculoskeletal pain.