Nasal dilator strips delay the onset of oral route breathing during exercise

The external nasal dilator strip (ENDS) device (Breathe Right^®, CNS Inc., Chanhassen, MN, USA) has been adopted by athletes to promote nasal route breathing during exercise. We studied the influence of ENDS on the switching point from nasal-only to oro-nasal breathing during exercise in 4 healthy men (age 25 ± 2 yrs, mean ± SEM) and 5 women (age 30 ± 5 yrs). Resting inspiratory nasal airflow resistance decreased from 0.33 ± 0.02 kPa/L/s without ENDS to 0.22 ± 0.01 kPa/L/s with ENDS (p < 0.01). ENDS delayed the onset of oro-nasal breathing such that the time from commencement of exercise to switching increased by 15.2%, and maximum levels of inspiratory nasal airflow and ventilation achieved prior to switching increased by 14.9% and 14.3%, respectively (all p < 0.05). We conclude that, in normal healthy subjects, ENDS does promote nasal route breathing during exercise, but any delay in the onset of oral route breathing during a progressive exercise task appears relatively small.