This video mentions the role of carbondioxide, which bridges the Wim Hof method and the apparently contradictory Buteyko method of breathing: 
[https://www.youtube.com/watch?v=OpTG02x6w5o]
While Wim Hof method powers up the body, [https://innovativemedicine.com/short-guide-breathing-right-buteyko-breathing-method/|Buteyko method] calms it down - both lead to more stress-resilience by breathing and pausing.
Buteyko method is often used to reduce asthma and anxiety, but also to enhance performance and dental health.