i find with boxing and any activity exhaling and the exertion part ie exhaling when you punch then you naturally want to inhale after. Some people make a hissing sound, some just breath and some shout but the effect is the same you have exhaled so your body naturally inhales after. Once i got into this habit i found i got tired less easily. Even if im playing football (soccer) and im sprinting for the ball i follow this rule.
My coach makes us practice taking three quick, consecutive deep breaths and holding them for four seconds and then exhaling with force. Oddly enough, it does help to catch your breath faster.
It's also good to breahte through your nose so you can keep you mouth closed and your jaw locked in place. But I've got a deviated septum and can't breathe out of my nose very well most of the time. So my mouth is always open a little bit. Thankfully I've got an iron jaw lol.
My coach always had me breathe when not in range. I'm tall & long for my weight, so after I'd finish throwing my shots, he'd have me step out of range, take advantage and breathe deep, and then restart. Breathing out when punching is always important as well. Exhale as you throw.
Breath out when you hit, breathing through your nose helps control and regulate fatigue compared to mouth breathing as said by doctors. Also cuts down on mucous production. You practise breathing while running, try breathing deep, in a pattern to music or whatever. Same with skipping. When you do work past your exertion threshold pay attention how you breath and come back to normal. Helps to practise that when you get a minute rest or catching your breath. If you want to work harder while you're already out of breath then many hills and sprints are needed to increase that ability.
Practice breathing from your diaphgram (spel?), the muscle you feel when you cough. When breathing try to reduce movement from your chest; your stomach should expand when inhaling ond colapse when exhaling. Also, when exhaling when punching usually takes the sting awy from counter punches.
