As a human, you are designed to breathe through your nose. You need to take fewer breaths through your nose than the average mouth-breather takes to deliver the same amount of oxygen to the lungs. As a fighter, breathing efficiently during training will benefit you in many ways; breathing efficiently in competition can give you a huge edge over an opponent.
Because you’ll need fewer breaths through your nose, you’ll actually be able to breathe slower, which in turn will allow you to be more relaxed in the thick of the fight. Plus every breath you save equals precious energy you’ll save as well. You’ll enjoy more stamina and focus, all thanks to your nostrils.