Effect of nostril dilatation on prolonged all-out intermittent exercise performance

Background. This study was designed to examine whether nostril dilatation would affect the ventilatory muscle (VM) function and the mean power output (PO) during prolonged all-out intermittent exercise. Methods. Eight untrained young male subjects each completed 30 bouts of all-out exercise 20-sec each on a cycle ergometer interspersed with 40-sec recovery periods under (i) normal breathing and (ii) nostril dilatation conditions. For nostril dilatation, external nasal dilator (END) was used. Pre-exercise peak nasal inspiratory flow (PNIF), pre- and postexercise maximum inspiratory (MIP) and expiratory pressures were assessed in all trials. During exercise, ratings of perceived magnitude of breathing effort (RPMBE) and exertion (RPE) were recorded at 5-min intervals while ventilation, tidal volume, breathing frequency and oxygen consumption (V̇O₂) were measured at 20-sec intervals. Results. Inspiratory muscle fatigue occurred during control trial as MIP reduced from 155.1±25.3 cm H₂O to 140.5±31.2 cm H₂O after the exercise. Pre-exercise PNIF was increased with END from 3.1±0.8 l·sec^-1 to 3.8±1.0 l·sec^-1 showing that the nasal airflow resistance was reduced. Using END during exercise eliminated inspiratory muscle fatigue (no change in post-exercise MIP), and resulted in low average RPMBE and RPE, and high PO in comparison with the control values. In addition, the augmentation of PO was concomitant with no change in the average values of the V̇O₂ and the ventilatory parameters. Conclusions. Exercise-induced VM fatigue occurs during the prolonged all-out intermittent exercise. Nostril dilatation with END during the exercise results in eliminating the VM fatigue and improving the PO.