Should You Breathe Through Your Nose or Mouth When Running?

Breathe through your nose, mouth, or both—whichever lets you run comfortably at the intended effort. Nasal breathing is an option, especially when it feels natural during easier running. If keeping your mouth closed makes you struggle for air, let it open or ease the pace.

A closed mouth is not a performance target. The more useful question is whether your breathing supports the workout you planned.

Why your mouth opens as effort rises

The breathing route changes how much air you can move. In a treadmill experiment involving 19 people, researchers compared nose-only and mouth-only breathing during four-minute stages at increasing intensities. Mouth breathing produced greater ventilation—the volume of air moved per minute.

That does not make every mouth breath better. The study measured short laboratory responses, not who ran the fastest race. Its authors also noted that some stages might have been too short for oxygen consumption to stabilize.

The practical implication is to leave room for your breathing to change when you accelerate, climb, or run intervals. You do not need to maintain the same route throughout a session.

What the nasal-breathing research actually shows

A frequently cited study of 10 recreational runners found no statistically significant difference in maximal oxygen uptake or treadmill time to exhaustion between nasal-only and oral-only conditions. The important detail: these runners had already chosen nasal-only breathing for training and racing for at least six months.

They could perform the tests through their noses, but that small, selected sample cannot establish that adopting the technique makes other runners faster. The study did not randomly assign runners to months of nasal training versus ordinary breathing.

It is also a mistake to assume closing your mouth automatically keeps a workout easy. In a separate crossover experiment, 19 adults completed hour-long, self-paced cycling sessions. Nasal-only breathing did not significantly change time spent in the measured training zones, and discomfort was higher. Cycling is not running, but the result cautions against treating breathing route as a precise intensity gauge.

Choose a response that fits the run

If you are curious about nasal breathing, notice it during a short, comfortable stretch of an ordinary easy run. Keep the route familiar and avoid changing the breathing pattern and pace at the same time. The question is whether it feels comfortable, not how long you can tolerate restriction.

Airway symptoms need their own explanation

Nasal breathing has a practical role in warming incoming air. The American College of Allergy, Asthma and Immunology includes trying it among suggestions for exercise-induced bronchoconstriction, alongside appropriate treatment and management of triggers.

That is not a reason to force it through breathing difficulty. Repeated wheeze, cough, or chest tightness deserves assessment; symptoms can have several explanations. If you already have asthma or an exercise-related breathing diagnosis, follow your treatment plan and discuss continuing symptoms with your clinician.

For everyday running, use a breathing route that lets you complete the intended effort comfortably. You can let your mouth open without turning the run into a technique failure.

This article draws on published laboratory studies and official clinical guidance. No original interviews or product testing were conducted. Small, short-term comparisons and a study of runners already accustomed to nasal breathing cannot establish a performance benefit for everyone. This is general information, not individualized medical advice.

This story was originally published by Men’s Fitness on Nov 2, 2026, where it first appeared in the Training section. Add Men’s Fitness as a Preferred Source by clicking here.