Resumen de Duathlon Performance Unaltered by Short-Term Changes in Dietary Fat and Carbohydrates
José Moncada Jiménez, Eric P. Plaisance, Michael L. Mestek, Lance A. Ratcliff, Felipe Araya Ramirez, J. Kyle Taylor, Peter W. Grandjean, Luis F. Aragón-Vargas
Purpose: This study investigated the effects of short-term dietary changes on metabolism and duathlon performance. Methods: Eleven men underwent a high-fat (HF; >65% fat from energy) or a high-carbohydrate (CHO; HC) diet (>60% CHO from energy). Energy intake was individualized, and commercially available foods were prepared and packaged for each participant 48 hr before they completed a laboratory-based duathlon (5-km run, 30 km cycling, and 10-km run). Blood samples were obtained before, immediately after, and 1 and 2 hr after the duathlon for determination of glucose, insulin, and glucagon. Oxygen consumption, ratings of perceived exertion (RPE), and respiratory-exchange ratio were assessed, and fat and CHO oxidation were estimated before, during, and after the duathlon. Results: Dietary records indicated a significant difference in fat content ingested before the duathlons (p < .05). Time to complete the duathlon did not differ between the HC- and the HF-diet trials. CHO-oxidation rate was higher during the HC-diet trial than during the HF-diet trial (p = .006). Fat-oxidation rates were higher in the HF-diet trial than in the HC-diet trial (p = .001). No differences in RPE were found between dietary trials. Blood glucose concentration was higher immediately after the duathlon in the HC-diet trial than in the HF-diet trial and remained higher 1 and 2 hr after the duathlon (p < .05). Conclusion: Duathlon performance was not altered by short-term changes in dietary fat or CHO composition despite higher blood glucose concentrations under the HC condition.
