Nasal Breathing for Performance

Nasal breathing provides no performance advantage for running at intensity and may reduce aerobic capacity delivery. The respiratory system is generally overbuilt for running demands. However, nasal breathing can help relaxation and control pacing on easy runs, and respiratory muscle training shows promise for elite athletes experiencing exercise-induced hypoxemia.

The Oxygen Cascade

Before evaluating breathing technique, understand oxygen delivery:

  1. Air intake → lungs (nasal or mouth doesn’t matter at this stage)
  2. Lung diffusion → bloodstream via alveoli
  3. Cardiac output → oxygen transport to muscles
  4. Capillary diffusion → oxygen reaches muscle fibers
  5. Mitochondrial utilization → energy production

Each step has a partial pressure gradient that drives oxygen down the cascade. Altitude impacts this because lower partial pressure means a shallower gradient—oxygen doesn’t cascade as readily.

Is Breathing a Limiting Factor?

In 90%+ of cases: No. Exercise physiologists consider the respiratory system “overbuilt”—we have more breathing capacity than we’ll ever need. Even during intense effort, oxygen saturation in your blood stays above 95% (essentially fully saturated).

Exceptions where breathing becomes limiting:
1. Altitude: Lower partial pressure forces the body to work harder to achieve full oxygen saturation
2. Exercise-induced arterial hypoxemia (EIAH): Well-trained endurance athletes with extremely high cardiac output push blood through the lungs so fast that full gas exchange doesn’t occur; their oxygen saturation drops despite sea-level conditions

In cases 1 and 2, the limiting factor shifts—breathing becomes a constraint. This is rare in recreational runners.

Nasal Breathing: The Myth vs. Reality

Claim: Nasal breathing improves performance through increased nitric oxide and deeper lung penetration.

Reality for performance: Data doesn’t support this. At intensities above 75-80% VO2max, nasal breathing becomes uncomfortable—you experience “air hunger.” This creates both a psychological signal (fatigue perception) and a physiological one (you literally can’t breathe in as much volume through your nose as through your mouth).

Research shows: At high intensities, nasal breathing either equalizes performance at best or slightly reduces it. Zero studies show it improves performance versus breathing through your mouth.

When Nasal Breathing Helps

At easy paces (below 75-80% VO2max):
No performance difference. Breathe however is comfortable.

For relaxation and pacing control:
Nasal breathing slows your breathing rate, which sends a signal to your parasympathetic nervous system (“everything is under control”). This is why box breathing and extended exhales help with anxiety. Using nasal breathing to keep yourself from going too fast on easy days can work as a control mechanism.

For health factors (not performance):
Nasal breathing may increase nitric oxide and has structural effects on facial development. These are legitimate health considerations but separate from running performance.

Respiratory Muscle Training

Unlike nasal breathing, respiratory muscle training shows promise, particularly for well-trained athletes. About 15-16% of VO2max goes to powering the respiratory muscles themselves (lungs, diaphragm, intercostals).

In highly trained endurance athletes, respiratory muscle fatigue can be a limiting factor because their cardiac output is so high that the respiratory muscles struggle to keep pace. Specific inspiratory trainers (not altitude masks, but devices that force deep respiratory effort) may help by:
– Increasing respiratory muscle endurance
– Reducing the oxygen demand going to breathing
– Freeing oxygen for working muscles

This effect is most relevant for elite athletes, not typical high school runners.

The James Nestor Critique

Nestor’s book “Breathe” presents a well-intentioned health argument for nasal breathing. However, his performance claims overreach:

  • He cites the 1968 Olympic team’s success at altitude, suggesting nasal breathing coaching helped. Reality: the sprinters excelled (sprints improve at altitude due to air density), while distance runners struggled—breathing coaching wouldn’t have changed this aerobic limitation.
  • He mentions Emil Zátopek’s breath-holding work. True, but modern research shows breath-holding doesn’t substantially improve performance, just shifts fatigue perception.

Health benefits of nasal breathing may exist; performance benefits for running at intensity do not.

Practical Recommendations

  1. Easy runs: Use nasal breathing as a pacing control if helpful. It may keep you from going too fast and promote relaxation.

  2. Moderate/hard efforts: Breathe however is comfortable. Don’t force nasal breathing; you’ll feel worse and perform worse.

  3. Respiratory muscle training: Only consider for well-trained runners (moderate to elite level) if you suspect respiratory muscle fatigue is limiting. Use specific respiratory trainers, not altitude masks.

  4. Don’t overthink it: The natural breathing pattern that emerges during running is optimized by your body. Overriding it with conscious control usually hurts performance.

Key Takeaway

Breathing matters, but not in the way popular advice suggests. Your respiratory system is robust and rarely limiting. Nasal breathing is fine for easy running and relaxation but offers no performance edge and can reduce capacity at hard intensities. For performance, focus on aerobic development, lactate threshold, and VO2max—not how you inhale.