Negative numbers?

How is it that I'm seeing negative numbers in Health in some matches? Shouldn't that be kind of impossible?

If you reach 0 in health and/or breath, you should be unable to continue, no?

Actually, when you reach negative health, you start to lose Breath recovery per action. I think it's like 1% loss per each hit point under zero you are, so at -100 HP, you lose 100% of your breath per action.

A loss in breath greatly diminishes your damage resistance, your ability to deal damage, and your ability to dodge and block attacks. So if you drop someone's health below zero, you've handed them a death sentence. They won't be breathing well for much longer.