Modulation of Pain Sensitivity by a Hyperventilatory Breathing Exercise and Cold Exposure Training

Abstract

Jelle Zwaag,1,2 Hans Timmerman,3,4 Peter Pickkers,1,2 Matthijs Kox1,2 1Department of Intensive Care Medicine, Radboud University Medical Center, Nijmegen, the Netherlands; 2Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, Nijmegen, the Netherlands; 3University of Groningen, University Medical Center Groningen, Department of Anesthesiology, Pain Center, Groningen, the Netherlands; 4Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, Nijmegen, the NetherlandsCorrespondence: Matthijs Kox, Radboud University Medical Center, Department of Intensive Care Medicine (710), Geert Grooteplein Zuid 10, PO Box 9101, Nijmegen, 6500 HB, the Netherlands, Email [email protected]: Evidence indicates that healthy individuals who follow a training program comprised hyperventilatory breathing exercises and cold exposure can voluntarily activate their sympathetic nervous system and attenuate their systemic inflammatory response during experimental endotoxemia (intravenous administration of bacterial endotoxin). Furthermore, trained participants reported less endotoxemia-induced flu-like symptoms. However, it remained to be determined whether the effects on symptoms are due to the mitigated inflammatory response or involve direct analgesic effects of (elements of) the training program.Methods: In the present study, we used Nijmegen-Aalborg Screening Quantitative sensory testing (NASQ) to objectively map pain sensitivity using non-invasive stimuli to address this question. First, NASQ parameters were evaluated in 20 healthy volunteers before, during, and after the conduct of the hyperventilatory breathing exercise. Second, NASQ measurements were performed before and after 48 healthy volunteers followed different modalities of the training program: breathing exercise training, cold exposure training, the combination of both, or no training. Lastly, NASQ measurements were performed in these 48 subjects during experimental endotoxemia.Results: Electrical pain detection thresholds increased during the breathing exercise (p = 0.001) as well as four hours afterwards (p = 0.03). Furthermore, cold exposure training resulted in lower VAS scores during hand immersion in ice water (p < 0.001). Systemic inflammation induced by administration of endotoxin nullified the decreased pain perception during the ice water test in subjects trained in cold exposure.Conclusion: A hyperventilatory breathing exercise decreases pain perception induced by an electrical stimulus. Furthermore, cold exposure training may decrease pain perception induced by hand immersion in ice water.Keywords: pain thresholds, hyperventilation, breathing, cold exposure, inflammation, endotoxin

Keywords

• pain thresholds
• hyperventilation
• breathing
• cold exposure
• inflammation
• endotoxin.