Does anyone have the problem that their airways are not fully open and they can't physically get enough air in through them? It's a real problem for me as I have to open my mouth and take a huge breath in when sparring and the gum shield doesn't help. My resting breathing is very audible when breathing through the nose and I was constantly congested as a child.
If you're not used to breathing through your nose it can take a while to get used to it. You need to force yourself to breathe through your nose as much as possible.
I used to have that problem, then I got my nose crushed in a submission grappling comp and it's fine now I wouldn't recommend it as a solution though.
Your parents didn't take you to a doctor when you were a child to figure it out? Have you had other sinus problems? Do you think you may have something else like sleep apnea? I agree. Go to a doctor (Don't do as Sifu Ben posted )
OP, if the DR says your all good, i.e. no physical obstruction, etc, can have a look at the complimentary therapy - 'Buteyko Method'. It is a type of breath training which trains people to, amongst other things, comfortably breathe through the nose.
Train how you fight. Do all your cardio work while wearing your mouthshield. Go jogging with it in, skip with it in, bag work with it in. Learn to breath with it in. If you constantly train without it, then sparring with it will feel alien.
