Physiological adaptations to training or overload stimuli, such as heat or cold exposure, are typically observable within 3 months.

“Well, the reason this happens is because heat, just like cold, is a shock or a stressor to the system. In the context of cold, if you get into a very cold ice bath, for instance, a five-degree ice bath, even for 20 seconds, it's known to increase norepinephrine 200%. [...] but if you were to do that every day, you would become cold adapted. This circuit that compares the shelling core of your body would adjust in ways that it could either predict that cold stimulus, or more likely to create some thermogenetic mechanisms in preparation for that cold exposure.”