I don't know if this helps but I can say for sure that there can't be a correlation that applies to everyone, because I can still easily maintain nose breathing (both inhaling and exhaling through the nose!!) even at 193 bpm which is around 94% of my max HR. my MAF would be 148 (153 if I didn't have to subtract, grr).

it's only from around 195 bpm and up that I have to open my mouth for more air.

so whatever. I don't think it's related to MAF in any way at all. I know I'm uncommon with my breathing but I have no idea why that is. would like to know why... anyone got an idea?

Is there a correlation between nose breathing and the MAF number?