The stress-hyperactivity-pain theory of myogenic pain: Proposal for a revised theory

The psychophysiological theory of stress-hyperactivity, as used to explain chronic benign muscle pain, contains two links: a direct link between stress and hyperactivity and an implicit link between hyperactivity and pain. Support for the stress-hyperactivity link within the psychophysiological theory is relatively strong if conceptual concerns about experimental methodology are taken into account. Support for the link between hyperactivity and nociception, however, is presently weak and, without support for that link, the overall theory is in serious trouble. The present neurophysiological data do not provide support for the purported vicious cycles between pain and hyperactivity at the segmental level as a causal explanation for such chronic pain. The role of human experience associated with the nature of stress and the pain related to chronic muscle states, however, may supersede the segmental neural mechanisms. A revised stress- hyperactivity theory is proposed that describes a higher-order vicious cycle of low-magnitude but persistent muscle activity that is stress-related and that leads to reduction in normal length of the associated muscle, reduction of stretch-induced aversive experience, and continued hyperactive states that protect against the pain and maintain the dysfunctional muscle condition.