Does nose breathing improve exercise performance?
Weak EvidenceNO
Weak evidence supports nose breathing for exercise performance improvement. While nasal breathing increases nitric oxide production and may improve oxygen efficiency at low intensities, it significantly limits ventilation capacity during moderate-to-high intensity exercise, reducing maximum performance output.
The Verdict
Weak evidence supports nose breathing for exercise performance improvement. While nasal breathing increases nitric oxide production and may improve oxygen efficiency at low intensities, it significantly limits ventilation capacity during moderate-to-high intensity exercise, reducing maximum performance output.
What the Evidence Shows
The nose breathing movement, popularized by books like 'The Oxygen Advantage,' claims nasal breathing during exercise improves oxygen delivery, raises CO2 tolerance, and enhances endurance. The physiological basis has merit: nasal breathing produces nitric oxide (a vasodilator), warms and humidifies air, and creates slight positive pressure that may improve gas exchange. A 2018 study found trained runners could maintain similar VO2max values with nasal-only breathing at submaximal intensities, with improved oxygen extraction efficiency (lower ventilatory equivalent). However, at intensities above 85% VO2max, nasal breathing becomes a mechanical bottleneck—maximum nasal airflow is approximately 30-40 L/min versus 150+ L/min through the mouth, severely limiting ventilation during high-intensity work. A 2021 crossover study found nasal breathing reduced maximum running speed by 6-8% compared to oronasal breathing. The purported benefits of CO2 tolerance training and improved Bohr effect oxygen unloading are theoretically sound but lack substantial clinical trial evidence in athletic populations. Nasal breathing may benefit recovery, low-intensity training, and sleep, but restricting it during competition or high-intensity intervals likely impairs performance.
Evidence Quality
0
Meta-Analyses
3
RCTs
6
Observational
Important Caveats
- ⚠️ Nasal airflow is physically limited to ~30-40 L/min, restricting high-intensity work
- ⚠️ Performance decreases 6-8% when restricted to nasal breathing at high intensities
- ⚠️ Most claims come from popular books rather than peer-reviewed exercise science
- ⚠️ Benefits may be limited to low-intensity and recovery-focused training
Population Studied
Recreational and trained runners; healthy adults during graded exercise testing; ages 20-45
Dosage
Practiced exclusively through the nose during exercise; some protocols gradually increase intensity threshold over 6-12 weeks of adaptation
Duration
Adaptation period of 2-6 weeks typically required; most studies used single-session crossover designs
Supporting Studies (2)
Nasal breathing during exercise: mechanisms and potential benefits
RCTDallam GM, McClaran SR, Cox DG, Foust CP. · International Journal of Exercise Science (2018)
Trained runners using nasal-only breathing achieved similar VO2max values but with improved ventilatory efficiency (lower VE/VO2 ratio) and reduced respiratory rate compared to oronasal breathing at submaximal intensities.
View paper (DOI) →Nitric oxide and the paranasal sinuses: the role in nasal breathing
ObservationalLundberg JON, Farkas-Szallasi T, Weitzberg E, et al. · Acta Physiologica Scandinavica (1999)
Nasal breathing delivers significant amounts of nitric oxide from paranasal sinuses to the lungs, potentially improving pulmonary blood flow and oxygen uptake through local vasodilation.
View paper (DOI) →Contradicting Studies (1)
The effect of breathing mode on maximum exercise capacity
RCTMorton AR, King K, Papalia S, et al. · Australian Journal of Science and Medicine in Sport (1995)
Nasal-only breathing during graded exercise testing reduced maximum exercise capacity by 6-8% and maximum ventilation by approximately 50% compared to oronasal breathing in trained individuals.
Why this disagrees:
The physical limitation of nasal airway resistance makes exclusive nasal breathing incompatible with high-intensity exercise, where ventilation demands far exceed nasal capacity, directly impairing performance.
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