[Repetitive strain injuries. Forearm pain caused by tissue responses to repetitive strain]

According to the National Research Council, painful work-related upper limb disorders are caused by different pathophysiological mechanisms, one of which is repetitive strain injury (RSI). Forearm pain, tenderness, and paresthesias are thought to result from a continual risk of exceeding limits of "cumulative trauma load tolerance" (CTLT, cf. NRC 2001) in soft tissue by thousands of high-frequency, repetitive movements. On the other hand, repetitive painful stimulations also produce neuroplastic changes in the spinal and supraspinal nociceptive systems. Thus, repetitive motor and nociceptive impulses become part of the same motor programs, which are also responsible for high-frequency movements and tissue damage. In this way RSI pain may be felt as a task-related response, even after all injuries are completely healed. Consequences of this neuroplastic CTLT model for RSI prevention and therapy are discussed.