If the brain can only survive 4-6 minutes without oxygen, how can freedivers hold their breath for 8+ minutes?

Question

And what about people like David Blaine or Tom Sietas? Sietas held his breath underwater for over 22 minutes (world record). I know they train for it like months and even years, but doesn’t holding your breath = no oxygen to brain?

Permanent brain damage apparently occurs just after 4 minutes of lack of oxygen to the brain, so why are freedivers left generally unscathed after 8 or 10 minutes without air?

In: Biology

Answer 1

Easy ELI5 boils down to one thing, adaptation. They’ve got factors working for them in their body plus they practiced a lot so their bodies adapted.