Introduction

Current debates around nasal vs mouth breathing may have you questioning if you know how to breathe at all. The good news — breathing is automatically controlled by your body, which adjusts naturally during exercise.

Why Nasal Breathing Is Trendy

Nasal breathing allows for filtration and humidification as air passes through your nose, making it increasingly popular among fitness enthusiasts.

What the Studies Say

1. Recinto et al., 2017 Nose vs mouth breathing didn’t impact power output or performance during all-out anaerobic exercise. Heart rate was higher with nasal breathing, but respiratory exchange ratio and hyperventilation were lower.
2. Rappelt et al., 2023 During low-intensity exercise, nasal breathing resulted in lower ventilation, CO2 release, O2 uptake, breathing frequency, and lactate. Participants reported higher discomfort, though RPE (rate of perceived exertion) was unchanged. Intensity of the session was similar between nasal and mouth breathing.
3. Morton et al., 1995 Nasal-only breathing during VO2 max testing slightly reduced maximal ventilation and tidal volume, with a large reduction in breathing frequency. Reduced FEO2 and increased FECO2, but all subjects achieved sufficient aerobic workload.
4. Niinimaa et al., 1980 Transition from nasal to mouth breathing occurs around 38% of maximal capacity in men and 55% in women (moderately trained subjects).
5. Other Findings Nasal breathing tends to decrease as exercise intensity increases (Wheatley 1991, James 1997, Bennet 2003). The switch supports higher oxygen delivery for faster exercise.

Key Takeaway

• Nasal breathing is fine during early-stage exercise.
• Your body naturally shifts to mouth breathing when needed — no overthinking required.
• Focus on comfort and efficiency rather than forcing nasal-only breathing at higher intensities.