Respiratory function during physical exercise in normal and obstructed noses.

Four healthy adults with normal nose were asked to pedal an ergometer for 3 min or more at a load of 25, 50, and 75 W/min, respectively. The same procedure was repeated on the same subjects whose nostrils were plugged. Air-flow and pressure difference between the mesopharynx and the nares, FO2 and FCO2, percutaneous-PO2 and ScO2 were recorded on a polygraph. At the start of the exercise, respiration deepened. Nasal resistance (Rn) decreased within 30 s and kept low while the exercise lasted. TcPO2 initially increased slightly for 1 min, then decreased. ScO2 also showed the same pattern, but of very slight range. At the end of the exercise Rn returned to pre-exercise level after slight rebound increase. Recovery of tcPO2 delayed for 30 s and its rebound increase lasted for more than 5 min. In case of nasal obstruction, such sequential changes of these parameters were of the same pattern as those in normal noses but were more evident. The results demonstrated that in case of moderate or severe nasal obstruction the exercise created hypoventilation despite a marked increase in the breathing activity if nasal breathing was continued.