Wim Hof breathing involves hyperventilation, exhalation, and breath holds, and liberates adrenaline to counter infection and stress.

“We know from this study entitled "Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans" showed really nicely, I think. That if people are injected with E. coli, a bacteria it's actually an end-- they did this through endotoxin injections. People got really sick. They'd get feel like they had the flu, they vomit, diarrhea, get a fever, et cetera. However if they did the sorts of breathing that I talked about just a moment ago, prior to that, they were able to ward off a lot of the symptoms associated with the endotoxin infection.”