The effect of pre-exercise diesel exhaust exposure on cycling performance and cardio-respiratory variables.

PURPOSE To determine the effect of pre-exercise exposure to diesel exhaust (DE) on 20-km cycling performance, pulmonary function, and cardio-respiratory variables during exercise. METHODS Eight endurance-trained males participated in the study. Test days consisted of a 60-min exposure to either filtered air (FA) or DE, followed by a 20 km cycling time trial. Exposures to DE were at a concentration of 300 µg/m³ of PM(2.5). Forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) were measured before and after exposure, and after exercise. Oxygen consumption (VO₂) and carbon dioxide production (VCO₂), minute ventilation (V(E)), tidal volume (V(T)), breathing frequency (F(B)), heart rate and oxyhemoglobin saturation (SpO₂), were collected during the time trials. The effect of condition on time trial duration, an order effect, and mean cardio-respiratory variables were each analysed using paired T-tests. Repeated-measures ANOVA were used to assess the effect of DE exposure on pulmonary function. RESULTS There was a main effect of condition (FA vs. DE) on the change in FEV₁ from baseline, and in exercise heart rate. Post hoc tests revealed that exercise-induced bronchodilation was significantly attenuated following DE compared to FA. There were no main effects of condition on 20 km cycling performance, or VO₂, VCO₂, V(E), V(T), F(B) and SpO₂ during a 20 km time trial. CONCLUSION A 60-min exposure to DE prior to exercise significantly attenuated exercise-induced bronchodilation and significantly increased heart rate during exercise. Pre-exercise exposure to diesel exhaust did not significantly impair 20 km cycling time trial performance.