[DiggyJohnson]

Yes, it’s crucial in fact.

[petodo]

I remember reading about it, but care to explain simply why it helps?

[TamDenholm]

Not an expert but my basic understanding is that the hyperventilating before holding your breath basically oxygenates your blood so that you can hold for longer.

[postsantum]

No, that's because hyperventilation washes out CO2 so the CO2 alarm going off later than usual