CONGRESS ABSTRACT

Background: Nasal and oral exclusive breathing modes have benefits and drawbacks during submaximal exercise. It is less known whether these responses would extend to anaerobic work performed at high intensity. The purpose of this study is to find the most efficient mode of breathing during different phases of a maximal exercise at cardiopulmonary exercise test (CPET). Methods Healthy subjects were recruited to perform 4 consecutive maximal CPETs using the same ramp protocol on an electronically braked cycle ergometer. The execution order (standard conditions (STD), exclusively nasal breathing (eNAS), exclusively oral breathing (eOR), partial nasal breathing (pNAS) with just one blocked nostril) were assigned in randomized order. Before the exercise a standard spirometry was executed in the same order. Results 12 healthy subjects (28.6±5.2 y, 50% males) performed the 4 CPETs within one month. Variables were analyzed at rest, at anaerobic threshold (AT) and at peak exercise. Compared to STD, eOR, and pNAS conditions, eNAS was associated with a significant lower peakVO2, peakVCO2, peak ventilation, respiratory rate, VE/VCO2slope, respiratory exchange ratio, and workload (Figure and table). Moreover, forced expiratory volume and vital capacity at rest were significantly lower, while peak inspiration and peak expiration time were significantly augmented. On opposite, no significant difference was detected at rest or AT. eNAS breathing Borg scale was significantly higher in all phases of the exercise. Spirometry showed a significant reduction in FEV1 in the eNAS condition.   Conclusion In young healthy subjects, an exclusively nasal respiration is related with a significant impairment on peak exercise capacity measured at CPET due to a ventilatory limitation, while is not significantly affecting metabolic parameters at rest and in a submaximal exercise.