@suesa, Wim Hof isn't an outlier, he has shown his method to many people. He goes on regular outings in the mountains with light layers of clothing with a group of around 26 people or so. Through breathing methods, they are able to activate re-active their brown fat repositories and convert visceral fat into heat....That's the claim at least. I've followed his methods and I've defiantly seen personal improvement. We hardly ever get the amount to oxygen in our blood as we are capable of getting, but through hyper-ventilation, the muscles take a lot more to fatigue and gives you way more strength. As for adrenaline, any form of bio-feedback can allow you to take control over a typically autonomic function with practice.