Influence of exercise intensity and nasal flow resistance on activities of human nasal dilator muscles

Abstract

Ten healthy subjects exercised on a cycle ergometer at 60, 120, and 150-180 W while breathing nasally. Nasal inspiratory flow, nasal dilator muscle (alae nasi; A.N.) EMG activities, and alveolar CO₂ and O₂ were measured at rest and at each work rate. On separate days six of the subjects exercised at 30-60, and 60-120 W while nasal airway resistance was measured by anterior rhinomanometry. In both protocols, 12-15 breaths of a He:O₂ (79:21%) gas mixture were substituted surreptitiously for air under each condition. He:O₂ breathing resulted in a decrease in flow turbulence and intranasal pressure, and therefore, resistance, as indicated by lower calculated Reynold's numbers. He:O₂ evoked an increase in nasal inspiratory flow, and reductions in nasal pressure and A.N. EMG activities (25-50%) at each work rate. These results suggest that A.N. EMG during exercise is controlled by increases in intranasal pressure, not by nasal flow. Thus, the data suggest that sensory information from pressure sensitive nasal receptors in the nasal lumen serve to modulate A.N. EMG activities during exercise.