And if you start from the old “breathe in through your nose, breathe out through your mouth” while you run recreationally or maybe exercise more seriously, you may be wrong, but maybe not!
While many professors, learned men, and less learned ones have repeatedly advised us that it is proper to breathe through the nose and exhale through the mouth, especially during physical activity, there is no evidence that it, nor another breathing pattern (whether nasal or oral) improves athlete performance.
Oxygen consumption, efficiency and fatigue, i.e overall performance, remain predetermined and limited by many other factors, but not by the manner or pattern of respiration.
“Breathe freely and never force yourself to do it in a way that is not natural to you,” says Dr. James Shafrat, Professor of Exercise Biology, Neurobiology and Physiology.
According to him, when it comes to exercise in any form (especially high aerobic sports) we all sometimes breathe through our mouths. “You can’t inhale 21 liters of air comfortably through your nose, can you?”
The only way that conscious breathing through the nose gives some benefits is when the ambient temperature and humidity are very low (in winter) so that the nose is the one that is able to warm the air before it goes to the lungs.
Bottom line – It doesn’t matter how you breathe while exercising, because the most important thing is to be comfortable. Never force yourself to breathe in a way that is not natural to you, as this will not improve your performance.