The effects of nasal breathing on ventilation and gas exchange during submaximal and maximal exercise

Abstract

Background: Nasal breathing during endurance exercise has become increasingly popular over the past few years. One argument favoring nasal breathing is its possibility to reduce asthma and exercise-induced asthma due to the ability of the nose to regulate temperature and humidity. Published research on how nasal breathing affects ventilation and gas exchange, compared to mouth breathing, in individuals who are accustomed to nasal breathing during endurance exercise is limited.

Aim: To investigate how nasal breathing during endurance exercise affects ventilation and gas exchange compared to mouth breathing in individuals accustomed to nasal breathing.

Method: Six recreational runners (5 male, 1 female) who were accustomed to nasal breathing during endurance exercise completed a submaximal and a maximal test using both mouth and nasal breathing. Ventilatory and gas exchange variables were measured both from inspired and expired air and in arterial blood samples during both submaximal and maximal exercise.

Results: Despite a significant reduction in VE during both submaximal and maximal exercise during nasal breathing (up to 32% during maximal exercise) (both p<0.001), VO2 during submaximal exercise and VO2max remained unaffected by the breathing method. The similar O2-uptakes during nasal breathing were substantiated by a significant decrease in FEO2 (both p<0.001). The reduction in VE was due to a lower RR (both p<0.001) and sustained Vt during both submaximal and maximal exercise. Compared to mouth breathing, nasal breathing resulted in lower PaO2 and SaO2, and higher FECO2 and PaCO2 during both submaximal and maximal exercise (all p<0.001). TTE was shorter during nasal breathing during maximal exercise (p<0.001).

Conclusion: Nasal breathing leads to a reduced VE, however it is still possible to produce a similar VO2 and VO2max. This indicates that the body compensates for the reduced VE trough an increase in Q and/or by maintaining a-vO2diff. The latter is expected to have the greatest impact. Nasal breathing is a feasible breathing method if warranted, mainly during submaximal exercise.