Overactivity in chronic pain, the role of pain related endurance and neuromuscular activity - an interdisciplinary, narrative review

Objectives: Decades of research have convincingly shown, that fear of pain and pain-related avoidance behavior are important precursors of disability in daily life. Physical underuse as a consequence of avoidance, however, cannot not be blamed for chronic disability in all patients, a contrasting behavior, pain-related dysfunctional endurance in a task and overactivity, have to be considered. Currently there is a need to better understand psychological determinants of overactivity, dysfunctional endurance and neuro-biomechanical consequences. Methods: Narrative review. Results: The first part of this review elucidates research on self-reported overactivity, showing associations with higher levels of pain and disability, especially in spinal load positions, e.g. lifting, bending or spending too long in specific positions. In addition, measures of habitual endurance-related pain responses, based on the avoidance-endurance model, related to objective assessments of physical activity and again, especially in positions known to cause high spinal load (part two). The final part reveals findings from neuromuscular research on motor control indicating the possibility that in particular overactivity and dysfunctional endurance may result in a number of dysfunctional adaptations with repetitive strain injuries of muscles, ligaments and vertebral segments as precursors of pain. Discussion: This narrative review brings together different research lines on overactivity, pain-related endurance and supposed neuromuscular consequences. Clinicians should distinguish between patients who rest and escape from pain at low levels of pain -but high levels of fear of pain - and those who predominantly persist in activities despite severely increasing pain until a break will be enforced by intolerable pain levels