Effects of an external nasal dilator on the work of breathing during exercise

Purpose: The effect of an external nasal dilator on the work of breathing ( WOB) was measured during exercise in 14 untrained college students (age, 23 +/- 2.7 yr). Methods: Two maximal, incremental ergometer tests were perfor med to exhaustion. Subjects wore a placebo or an active nasal dilator strip , in random order, during each test. An esophageal balloon was placed throu gh each of the subject's mouth into the esophagus for measurement of inspir atory elastic work (INEW), inspiratory resistance work (INRW), and expirato ry resistive work (EXRW). Subjects breathed through a Hans Rudolph(R) face mask that covered both the mouth and nose during both tests. Measured varia bles included oxygen uptake ((V) over dot O-2), ventilation ((V) over dot ( E)), tidal volume (V-T), frequency of breathing (f), INEW, INRW, and EXRW ( work expressed in joules). An alpha level was set at P < 0.05. Results: No significant differences were found in INEW, INRW, and EXRW between conditio ns at 70% of (V) over dot O-2max (mean +/- SD; Placebo: INEW, 25.6 +/- 17.8 J.min(-1); INRW, 22.4 +/- 15.8 J.min (1); EXRW, 16.7 +/- 12.3 J.min(-1): A ctive: INEW, 24.7 +/- 12.9 J.min (1); INRW, 19.7 +/- 11. J.min(-1); EXRW, 1 5.2 +/- 8.6 J.min(-1); P > 0.05). No difference was found in INEW, INRW, an d EXRW at maximal exercise between conditions (mean +/- SD; Placebo: INEW, 50.2 +/- 29.9 J.min(-1); INRW, 67.3 +/- 42.3 J.min (1); EXRW, 102.3 +/- 78. 4 J.min(-1); Active: INEW, 45.7 +/- 19.6 J.min(-1); INRW, 62.6 +/- 36.7 J.m in (1); EXRW, 86.3 +/- 50.9 J.min (1); P > 0.05). There were no differences in (V) over dot O-2, (V) over dot (E), V-T, or f between conditions.