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Should You Breathe Through Your Mouth or Nose During Exercise?

Everything we know about breathing might be wrong.

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Next time you go for a run, pay attention to the way you breathe: Do you inhale and exhale solely through your nose? If you’re like most athletes, probably not – and that might be hindering your performance. Here’s the answer to the age-old question, “Should you breathe through your mouth or nose when running?”

“As a modern culture, we have primarily defaulted to a by-mouth approach to breathing during exercise, falsely assuming that we cannot adequately oxygenate ourselves by breathing though our nose,” explains Dr. George M. Dallam, former USA Triathlon National Team coach and current professor of exercise science and health promotion at CSU-Pueblo. “And the result of this is a nearly epidemic rate of exercise-induced bronchoconstriction in endurance athletes.”

In layperson terms, many athletes are breathing their way into an asthmatic response. Dallam’s recently-published analysis in the Journal of Sports Research is the first comprehensive review to actually investigate the common assumption that oronasal (nose and mouth) breathing is superior. As it turns out, it’s not.

Dallam says our noses are specially designed to filter, humidify, and regulate the temperature of the air we inhale. When we breathe our mouths, the air doesn’t get the same treatment—mouth-inhaled air that hits the respiratory passages, called bronchi, is often drier and colder, causing the bronchi to constrict. This is called exercise-induced bronchoconstriction, or EIB. Symptoms of EIB—shortness of breath, tight chest, coughing, decreased endurance, or sore throat—typically appear within a few minutes after exercise begins, and continues for a short period after the workout concludes.

We haven’t always been mouth-breathers. Dallam says some anthropological evidence suggests that early man breathed predominately through the nose, even when moving over ground rapidly. Nose-breathing practices are also seen in existing cultures that still practice ancient running traditions, such as the Rarámuri (or Tarahumara) tribe in Copper Canyon, Mexico.

But somewhere along the way, endurance athletes started to think of air as a performance-enhancing drug—if a little bit of oxygen is good, a lot must be better! Advice shifted to encourage oronasal breathing, with the belief that breathing only through the nose limits the maximum amount of air we can breathe, thus inhibiting our ability to perform work. In doing so, we created a new problem: EIB. After all, asthmatic responses aren’t ideal when trying to catch the lead pack or chasing down a new PR.

But Dallam’s recent research found that when subjects take the time to adapt to breathing nasally, they are able to perform just as well at anaerobic efforts than when breathing in oronasal fashion. In addition, Dallam’s study found that in steady-state efforts, the total oxygen needed to run at a given pace is reduced when breathing nasally, a concept known as physiological economy. “This suggests that breathing may offer some potential for performance improvement as well,” Dallam says.

For those looking to adapt to nasal breathing, Dallam first preaches patience—adaptations will take time. In his research, complete adaptations at all levels of intensity ranged from six weeks to six months, depending on an individual’s current level of CO2 sensitivity and how diligently they applied the concept of nasal breathing.

“The most effective approach is to slow everything down a level just below where you feel air hunger, then gradually increase work rate as the sensations go away. This is easily monitored by occasionally  training on a treadmill or indoor bike and using a progressive warm-up, where you increase your work in stages,” explains Dallam. Some other tips for adapting to nasal breathing:

  • Keep small sips of water in your mouth—this will naturally prompt you to keep your lips sealed.
  • Nasal strips and internal dilators may be helpful, though Dallam suggests reserving them for high-intensity sessions and racing.
  • Initially, this approach will cause your nose to run. Keep a handkerchief handy in a jersey pocket until you adapt.
  • Use a neti pot daily to rinse debris and mucus from your nasal cavity—nasal breathing during exercise places a large additional load on the filtering process of the nose.


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