Earlier quoted context omitted.
That is because he got it from the Buddhist Tummo techniques. >It has similarities to Tibetan Tummo meditation and pranayama, both of which employ breathing techniques.[25] https://en.wikipedia.org/wiki/Tummo I won’t say he appropriated it, because he is quite open about it and adapted it, but it did not originate with him.
I don't think so. I know that he was interested in Buddhist stuff (source: some documentary). But when I talked to him, he told us (part of the Radboud experiment in 2014, I think) that he just jumped into cold water and was forced to learn how to breath in such a way that he wouldn't freak out. Note/edit: As you can see from my writing my memory isn't pinpoint accurate. Given that the article was published in 2014 […
Things do not exist in a vacuum, though. Especially something such as breath would be pretty universal despite in what cultural context.