# Ventilatory Responses to Progressive Treadmill Speeds in Women: A Comparative Analysis of Nasal, Oral, and Oronasal Breathing Conditions

## TL;DR

The study compares how breathing through the nose, mouth, or both affects ventilation and exercise performance in women at different treadmill speeds.

## Contribution

It reveals that nasal breathing becomes inefficient at higher exercise intensities, suggesting oral or oronasal breathing is better for vigorous activity.

## Key findings

- Nasal breathing led to reduced ventilatory efficiency at higher treadmill speeds (10–11 km/h).
- Oral and oronasal breathing supported better ventilation with increased exercise intensity.
- Nasal breathing may cause CO2 accumulation and early fatigue during vigorous exercise.

## Abstract

Background: Breathing conditions influence ventilatory efficiency and exercise performance, but little research has examined how different breathing conditions affect cardiorespiratory responses in women. Despite the growing popularity of nasal-only breathing in fitness culture, its physiological benefits remain unclear. The purpose of the current study is to examine the ventilatory responses to nasal, oral, and oronasal breathing during treadmill exercise at speeds of 5 to 11 km/h in 10 healthy females. Methods: Participants completed sessions under each breathing condition while heart rate (HR), oxygen uptake (VO2), ventilatory equivalent for CO2 (VE/VCO2), respiratory frequency (Rf), tidal volume (VT), minute ventilation (VE), and respiratory timing variables were measured. Results: Breathing condition had minimal impact at lower speeds (5–7 km/h). However, at higher intensities (10–11 km/h), nasal breathing resulted in lower Rf and VE but elevated VE/VCO2, indicating reduced ventilatory efficiency. In contrast, oral and oronasal breathing facilitated greater VE and shorter inspiratory and expiratory times, supporting ventilation under vigorous exercise. Conclusions: While nasal breathing may suffice at low intensities, it is inadequate at higher intensities, potentially leading to carbon dioxide accumulation and early fatigue. These findings support the use of oral or oronasal breathing during higher-intensity activity and highlight the need for individualized breathing strategies.