There is a growing awareness that good breathing function can impact on health and fitness.  Often runners and people in the gym are breathing through their mouths, this may be necessary during short high impact exercise, but it should not be the default mode. When you breathe through your mouth, you are effectively hyperventilating and not efficiently using the oxygen.   

​

 When you breathe through your nose, the increased resistance will allow for more oxygen to be offloaded to your tissues based on the increased levels of carbon dioxide in the blood. This is called the Bohr Effect.  Nasal breathing also releases nitric oxide, opening up the airways and allowing for more oxygen uptake to the tissues.