The magnitude of exercise-induced hypoalgesia can be improved and correlated with endogenous pain modulation following 4 weeks of treadmill running

Objective We aimed to investigate changes in pain perception, acute exercise-induced hypoalgesia (EIH), and endogenous pain modulation responses following 4-week treadmill running exercises of different intensities in healthy individuals. Methods Fifty-six healthy individuals included in this study. All participants were randomly assigned to three experimental groups (TRH, high intensity running, TRM, moderate intensity running and TRL, low intensity running). All participants performed 12 treadmill running sessions within 4 weeks at different intensities based on their target heart rate (THR). A running assessment was administered one week before running sessions. The magnitudes of EIH, conditioned pain modulation (CPM), and temporal summation (TS) responses following regular treadmill running were assessed. Pressure pain thresholds (PPT) or mechanical pain thresholds (MPT) were also determined following regular treadmill running. Results Treadmill running only induced acute EIH responses, with all pre-running PPT and MPT remaining unaltered. The acute EIH following each running sessions and CPM responses were also significantly improved in both the TRM and TRL groups, with TS score decreased in the TRM group. Conclusions A 4-week low to moderate intensity treadmill running improved acute EIH response by enhancing endogenous pain modulation in healthy individuals. Future studies should consider sex, behavior, and physiological factors to provide a comprehensive understanding of the changes in EIH following regular exercises.