Physiological Responses to Diesel Exhaust Exposure Are Modified by Cycling Intensity.

• Autores: Luisa V. Giles, Jason P. Brandenburg, Christopher Carlsten, Michael S. Koehle
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 46, Nº. 10, 2014, págs. 1999-2006
• Idioma: inglés
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• Resumen

  • AB Background: Outdoor exercisers are frequently exposed to diesel exhaust (DE) that contains particulate matter (PM) air pollution. How the respiratory and metabolic responses to exercise are affected by DE exposure and how these responses change with exercise intensity are unknown. Purpose: This study aimed to determine the respiratory and metabolic responses to low- and high-intensity cycling with DE exposure containing high levels of PM. Methods: Eighteen males age 24.5 +/- 6.2 yr performed 30-min trials of low-intensity (30% of power at V[spacing dot above]O2peak) and high-intensity (60% of power at V[spacing dot above]O2peak) cycling as well as rest. Each trial was performed once while breathing filtered air (FA) and once while breathing DE (300 [mu]g[middle dot]m-3 of PM2.5) for a total of six trials, each separated by 7 d. During the trials, minute ventilation (V[spacing dot above]E), oxygen consumption (V[spacing dot above]O2), CO2 production (V[spacing dot above]CO2), RER, and perceived exertion for lungs (RPELungs) and legs (RPELegs) were measured. Work of breathing, respiratory muscle V[spacing dot above]O2, ratio of O2 consumption to power output, and gross efficiency were estimated. Results: The RER was significantly lower (0.02 lower, P = 0.008), and the RPELungs (0.9 greater, P = 0.001) and the RPELegs (0.6 greater, P = 0.017) were significantly greater, in DE compared with FA. During low-intensity exercise, V[spacing dot above]E (44.5 +/- 8.9 vs 40.5 +/- 8.0 L[middle dot]min-1, P < 0.001), V[spacing dot above]O2 (27.9 +/- 5.4 vs 24.9 +/- 4.4 mL[middle dot]kg-1[middle dot]min-1, P = 0.001), and V[spacing dot above]CO2 (25.9 +/- 5.3 vs 23.5 +/- 4.5 mL[middle dot]kg-1[middle dot]min-1, P = 0.006) were significantly greater in DE. This pattern was not seen during high-intensity cycling. Conclusions: Respiratory and metabolic responses to low-intensity, but not high-intensity, cycling in DE exceed FA. Practically, the greater responses during low-intensity exercise in DE could have implications for individuals with cardiopulmonary disease. Also, the elevated RPE during DE could impair performance in self-paced exercise