Never heard about "hiding" it explictly, but I never do regular long cycle predictable breahing in fighting, if you get hammered in your body at fast pace, there is not time slots for breathing normall, so the one way I found out from experimenting is to breath simultanously are short shallow breathing. Works fine. And when i plan to eat attacks i explicitly tense up with a shallow exhale on impact, like a kiai on taking the attack rather than delivering it. Works well for me. It also is natural part of toughening. It is also deterring to opponent when they realize that their attacks has no effect, then you get mental advantage.