There's plenty of success stories on youtube about wim hof -method, so it probably works. Feels like I will try it.
I have not been overly convinced by Wim's explanations what happens in the body when doing breathwork and cold exposure stuff.. But there's plenty of information available what happens in the body when you do that stuff.
Cold exposure causes mitochondria biogenesis (more mitochondrias are created) on location of cold exposure on body. Mitochondrias make the heat in body. Thyroid makes thyroid hormones (T3) that are needed in that process. Cold exposure also causes urge to hyperventilate, which induces
fight-or-flight response. That releases
norepinephrine hormone, which cause brown fat make more heat, heart pump more blood and some arteries dilate and some constrict. It also makes energy more available from fats and glycogen. And Multiple effects on the immune system - the effects are complex, with some immune processes activated while others are inhibited.
Breathwork of Wim Hof method is probably meant to induce fight-or-flight response without cold exposure. Because there's breath holding involved, it has some indenpendent effects. Because hyperventilation makes carbon dioxide low and it's high carbon dioxide that causes
urge to breathe, it's easier to get deeper into oxygene deprivation. When there's lack of oxygene in the body and higher carbon dioxide, spleen contracts and releases red blood cells into blood, which makes blood has better capacity for oxygene transportation. Wikipedia don't tell if this effect is bigger with deeper oxygene deprivation, though. But atleast it's possible to do longer full body immersions (bit risky though) or just facial immersions, which cause diving reflex which has it's own set of effects - the cardiovascular system displays peripheral vasoconstriction, slowed heart rate, redirection of blood to the vital organs to conserve oxygen, release of red blood cells stored in the spleen. Also
sticking your face in ice water works because the vagus nerve in your face is connected to nerves in the rest of your nervous system throughout your body. By using this simple trick to get the nerves in your face used to the cold, it will translate over to the rest of your body as well, and allow you to tolerate ice baths and cold showers far more easily.
So by doing breathing and cold exposures it's possible to get more mitochondrias and red blood cells and practice probably makes fight-or-flight response and diving reflex more efficient - faster and stronger?
BTW, makes me wonder if nasal breathing is that useful when running.. Sounds like this fight-or-flight would be better. Maybe body actually shouldn't be in rest and digest mode when exercising.