Which one was the hot one?

the one with the braces!

Some good "O" faces in there, fo shizzle.

i thought it would make a good reality show, actually...

I think they hold their breath until they're going as fast as they're going to, so "On top, breathe" makes sense. I think.
I don't know about the other thing.

The high-G exercises you use to gain an extra few seconds of consciousness involve tightening every muscle below your chest, including your diaphragm, so you can't breathe normally, just in little gasps. If you're not well trained your instinct is to stop breathing and just do a full-on constipation grunt. That's my guess.

Also that little spasming wake-up dance is nicknamed "Doing the Funky Chicken".