Breathing through your mouth for hours at a time _while_ doing that ^. Also not good. Your gums get dried out. Lots of endurance athletes take the "long in the

Breathing through your mouth for hours at a time _while_ doing that ^. Also not good. Your gums get dried out. Lots of endurance athletes take the "long in the tooth" look a few steps further than usual. https://www.ucl.ac.uk/news/2018/jun/high-levels-oral-disease-among-elite-athletes-affecting-performance https://www.ucl.ac.uk/news/2018/jun/high-levels-oral-disease...