See more of the story

When you are exercising — running, hiking, dancing, lifting weights, whatever you like to do — do you breathe out of your nose or mouth?

If you are like most exercisers, you breathe through your mouth, especially as the intensity of the exercise mounts. But experts are learning that breathing through the mouth may not be as efficient or effective as breathing through the nose.

Nasal breathing can allow for more oxygen to get to active tissues. That is because breathing through the nose releases nitric oxide, which is necessary to increase carbon dioxide (CO2) in the blood, which, in turn, is what releases oxygen. Mouth breathing does not effectively release nitric oxide, which means the cells are not getting as much oxygen as through nasal breathing, which could lead to fatigue and stress.

A recent study demonstrated this. The study tested 10 runners who were put through standardized testing, once with nasal breathing and then with mouth breathing, to compare their maximum oxygen intake rates. They were also tested for various other respiratory and exercise markers, including oxygen and carbon dioxide levels while exercising.

Their maximum rate of oxygen consumption did not change from nasal to mouth breathing. But their respiratory rate, breaths per minute and ratio of oxygen intake to carbon dioxide output decreased during nasal breathing.

Nasal breathing also activates the part of the nervous system that supports rest, recovery and digestion, rather than the part of the nervous system that is responsible for survival or stress states, such as flight or freeze. That means that even if the body is in a stressful state of high-intensity exercise, nasal breathing can provide a sense of calm and allow us to function better.

“It’s incredibly difficult to learn or process anything in survival mode,” said Brian Mackenzie, founder of the Art of Breath, a program that teaches how to use breathing to optimize athletic performance. “We are now understanding some of the deeper layers to managing stress, which has direct impact on not only the general population, but is at the heart of how elite performers can optimize performance.”

So, how can we do more nasal breathing? Start by paying attention to your breathing habits. Do you more often breathe through your nose or mouth during the day? What about while exercising, especially as the workouts get more difficult? Once you know what it feels like to pay attention to your breath, practice nasal breathing. Close the mouth and relax the tongue and jaw. Start by simply nasal breathing during warmups and cool-downs with workouts. Then try experiencing daily life while breathing through the nose.

Mackenzie said he believes that nasal breathing not only improves athletic performance but also can improve our awareness. “To desire a mind that remains curious and can see the beauty in any experience is true freedom,” he said. “Our breath is the direct link to a calm, clear mind and body.”