VENTILATORY KINETICS DURING TREADMILL RUNNING IN CHINESE MALES

Abstract

Although a number of studies have investigated the effects of external nasal dilators on peak oxygen uptake and other tests of peak performance, none appear to have reported data from ventilatory kinetics studies, particularly during treadmill running. Even though the nasal dilator strip appears not to affect steady-state measurements taken during these moderate-to-high intensity exercises, it may decrease the time taken to reach a ventilatory steady-state by reducing nasal resistance early in exercise when nasal breathing is more likely to occur. PURPOSE: To investigate the effect of an external nasal dilator on the time constant of the ventilatory response to treadmill running. METHODS: Twenty young Chinese male athletes (mean ± SD, age: 21 ± 2y; height: 173 ± 4cm; mass: 66 ± 8kg) with normal lung function had their ventilatory kinetics (single exponential model) monitored on three separate days. Exercise consisted of 6 discontinuous 5-min increments up to near-maximal treadmill exercise, under a randomly assigned control, placebo or nasal strip condition. Oral and nasal ventilation were separately monitored using a new lightweight mask and data-acquisition system (Macfarlane and Liu, 2001). RESULTS: The ventilatory time constant gradually increased from Stage 1 (∼31s) up to Stage 6 (∼67s) of exercise. With only one exception, no statistically significant differences between the control, placebo and nasal strip conditions were seen during the first 5 stages of exercise (p > 0.05, ANOVA). At near-maximal exercise (Stage 6), the time constant in the nasal strip condition (58 ± 8s) was significantly faster than the placebo condition (76 ± 13s), but not when compared to the control condition (68 ± 17s). CONCLUSION: These results suggest that the external nasal dilator has no physiological benefit in reducing the time taken for ventilation to reach a steady-state during treadmill exercise of less than near-maximal effort. At near-maximal effort a small benefit may occur, although further well-controlled studies are needed to clarify whether this effect does exist.