that's why i always hyperventilate with every hand i'm dealt.
lol
This is high-level mind games; you are concealing your tells. Hey, at least you are aware of your tells; the ones that get players into trouble are the tells they don't know they are giving off.
(pretty sure the hyperventilating every hand was a joke, but I like the humor)
Serious response though: heavy breathing is just like any other tell-based piece of information. We have to figure out what heavy breathing means for that specific player. From my experience, heavy breathing usually indicates they believe they have a strong hand; but some players I know just get anxious when the pot gets big or some crucial card hits the board - regardless of their hand strength, they start to breath heavier. It just depends on the person.
I suppose some players might breath heavier when they bluff, but most beginning players don't bluff in the exact way that regs do. If someone raises me big in a bluffy-looking way, I will usually give them credit for the hand because they usually don't have the ability to bluff and make moves like this without giving off other tells. If someone does this say three times against me: all right, now I suspect they are making moves and I need to adapt by testing them more often.