The bends are caused by accumulated nitrogen dissolving in tissue\blood. No breathing, means no added nitrogen, so no build up. Also it is a somewhat slow process, no breathing means they aren't under long enough for it to develop even if they had extra nitrogen.
It is a problem caused by Scuba, and the fact that Scuba does what it is supposed to, extend the time you can spend underwater, is what causes the bends.
It is a problem caused by Scuba, and the fact that Scuba does what it is supposed to, extend the time you can spend underwater, is what causes the bends.