Alterations in endogenous pain modulation in endurance athletes: An experimental study using quantitative sensory testing and the cold-pressor task

Abstract

There is evidence for long-term alterations in pain tolerance among athletes compared with normally active controls. However, scientific data on pain thresholds in this population are inconsistent, and the underlying mechanisms for the differences remain unclear. Therefore, we assessed differences and similarities in pain perception and conditioned pain modulation (CPM) at rest in endurance athletes and normally active controls. The standardised quantitative sensory testing protocol (QST) of the 'German-Research-Network-on-Neuropathic-Pain' was used to obtain comprehensive profiles on somatosensory functions. The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. CPM (the diffuse-noxious-inhibitory-control-like effect) was measured using 2 tonic heat pain test stimuli (at the temperature exceeding a subjective pain rating of 50/100) separated by a 2-min cold-pressor task (CPM-TASK; conditioning stimulus). Pain ratings were measured with a numerical rating scale. Endurance capacity was validated by assessment of maximum oxygen uptake (VO2max). Participants included 25 pain-free male endurance athletes (VO2max>60mL/min∗kg) and 26 pain-free normally active controls (VO2max<45mL/min∗kg) matched based on age and body mass index. Athletes were significantly less sensitive to mechanical pain but showed higher sensitivity to vibration (P<0.05). In athletes, CPM was significantly less activated by the conditioning stimuli (P<0.05) when compared with normally active controls. Our data show that somatosensory processing in athletes differs in comparison with controls, and suggest that the endogenous pain inhibitory system may be less responsive. This finding may explain the paradoxical propensity of athletes to develop chronic widespread pain.

Exercise-Induced Hypoalgesia Profile in Rats Predicts Neuropathic Pain Intensity Induced by Sciatic Nerve Constriction Injury

“…60 Triathletes' CPM was significantly enhanced compared to nonathletes', 18 and reduced responses to conditioning stimuli have been found in endurance athletes. 60 Interestingly, there was no early difference found between habituated and nonhabituated rats following exercise in this study. The nonhabituated rats' pain reduction following exercise was not different from the habituated rats' pain reduction 1 and 5 minutes following the exercise.…”

“…24,34 Studies on athletes have shown that their somatosensory processing differs in comparison with controls. Athletes demonstrated reduced sensitivity to mechanical pain, 60 reduced sensitivity to cold stimulation, 25 but increased sensitivity to vibration. 60 Triathletes' CPM was significantly enhanced compared to nonathletes', 18 and reduced responses to conditioning stimuli have been found in endurance athletes.…”

“…Athletes demonstrated reduced sensitivity to mechanical pain, 60 reduced sensitivity to cold stimulation, 25 but increased sensitivity to vibration. 60 Triathletes' CPM was significantly enhanced compared to nonathletes', 18 and reduced responses to conditioning stimuli have been found in endurance athletes. 60 Interestingly, there was no early difference found between habituated and nonhabituated rats following exercise in this study.…”

Exercise-induced Hypoalgesia Profiles for Pain Prediction in the Trigeminal System

“…Previous studies on athletes have shown that their pain perception differs in comparison with the control group. Athletes had reduced sensitivity to cold and mechanical stimuli, 38,39 but increased sensitivity to vibration. 38 The increased response to vibration mediated by A-beta fibers (mechanical allodynia) is an interesting finding, as the vibration detection threshold was the only test that tends to gain more sensation (more sensitive perception).…”

Sensitivity to pain and strategies of coping with stress in combat athletes

“…Athletes are a group particularly exposed to pain caused by injuries. A number of authors claim that athletes are more tolerant of pain and have higher pain thresholds compared to non-training population [2,3], which has been confirmed by numerous studies assessing the physiological, neurological, cultural and psychoanalytic causes of pain [4]. Researchers increasingly emphasize that athletes' conscious and unconscious attitudes, their motivations and anxiety levels (subjectively perceived risks) are elements which should be taken into consideration while investigating pain reactions.…”