I have conditioned myself to freedive over many years. I started out barely getting past 20 feet. Now I can easily hit 60. However, the chance of shallow-water blackout has not changed. In fact, shallow water blackout is most common in people who freedive all the time and have conditioned their bodies to "ignore" the feeling of needing air. I know this is a different topic, but I'm relating it to swimming in the cold because it's similar in that you condition yourself to go beyond where you normally would.

I'm curious if when people are conditioned to cold water do they reach a point where hypothermia still sets in but more rapidly. In other words, I wonder if they would go from feeling okay to being totally hypothermic with no in-between area like you and I would. With shallow water blackout you just go from swimming along minding your own business to dead. Boom. You pass out, and if not brought to surface in just seconds you will die. The few that have survived have said there was no feeling of needing air, no warning- just suddenly they blacked out. I wonder if a person conditioned to cold would still reach a point where they just rapidly hit hypothermia similar to free-divers that black out suddenly.

Cheers,

Malcolm