The second blackout was totally predicted a mile away. The diver was clearly out of breath seeing that he's using arm and leg stroke together so he could get to the wall faster but instead he just decided to go for another round while what he had to do is to go up immediately!!!
This is like a hamer smashing into your brain for the brain itself with such a lack of oxygen, though they need to train somehow, many blackouts can cause so much trouble at a later time.
this is not correct. blacking out is a protective mechanism of the body that engages long before any permanent damage could occur. as long as somebody helps you to regain consciousness quickly you are fine.
