The combination of cold exposure training and a breathing exercise attenuates the inflammatory response in humans

Background - We previously showed that a training intervention encompassing two breathing exercises and exposure to cold enables for voluntary activation of the sympathetic nervous system, reflected by profoundly increased plasma adrenaline levels, and subsequent attenuation of the endotoxin-induced inflammatory response. Herein, we determined the contribution of the different elements of the training, assessed if the training duration is of importance, and whether it can be provided by an independent trainer instead of the well-known individual who devised it. Methods – Forty healthy male volunteers were randomized to either a short or extensive training in both breathing exercises (i.e. cyclic hyperventilation with or without prolonged breath retention) by either the creator of the intervention or an independent trainer. In a subsequent study, 48 healthy male volunteers were randomized to cold exposure training, training in the established optimal breathing exercise, a combination of both, or no training. All 48 subjects were subsequently intravenously challenged with 2 ng/kg lipopolysaccharide to induce endotoxaemia. Results - Both breathing exercises were equally effective in enhancing plasma adrenaline concentrations and this response was also independent from the length of the training or the individual who provided it. Cold exposure training alone did not result in relevant modulation of the endotoxin-induced cytokine response, although flu-like symptoms were markedly reduced compared with the untrained group. Whereas subjects who received training in the breathing exercise alone displayed attenuated plasma levels of pro-inflammatory cytokines IL-6, IL-8, IP-10, MCP-1, MIP-1α, and MIP-1β (-34%, -14%, -48%, -37%, and -28%, respectively) during endotoxemia, combined training resulted in enhanced concentrations of anti-inflammatory IL-10 (+44%) and reduced concentrations of TNF-α, IL-6, IL-8, IP-10, MCP-1, MIP-1α, and MIP-1β (-32%, -35%, -30%, -48%, -29%, -35%, -30%, respectively) compared with untrained individuals. Conclusions - The combination of cold exposure training and a hyperventilation breathing exercise attenuates the in vivo inflammatory response most potently. Our study demonstrates that the immunomodulatory effects of the intervention can be reproduced in a standardized manner, thereby paving the way for clinical trials. Trial registration - Both studies described in this manuscript are registered at www.clinicaltrials.gov (breathing exercises study: NCT02417155; experimental human endotoxaemia study: NCT03240497).