[PopeOfNope]

Back in the early 90's, a fellow runner and a friend used to do this after cross country races. She never won a medal. She would push herself like this because she enjoyed it. That said, I don't think it's healthy either. Not from the lack of oxygen[0], but rather from the need for the endorphine high.

[0]: at 18, you can't push your body hard enough to do permanent damage from running. I know several people who tried, though.