Resumen de Physiological Impact of a Single Serving Slow Absorption Carbohydrate on Metabolic, Hemodynamic, and Performance Markers in Endurance Athletes During a Bout of Exercise
Patrick M. Davitt, Catherine Saenz, Troy Hartman, Phil Barone, Steven Estremera
The purpose of this study was to determine how a slow-absorbing carbohydrate affected markers of metabolism, hemodynamics, and performance in well-trained endurance athletes. We examined total and exogenous carbohydrate oxidation (CHO ox), glucose, and performance after consuming different glucose beverages, before a treadmill run. Ten male runners (32.4 years; V[Combining Dot Above]O2max, 55.9 ml[middle dot]kg-1[middle dot]min-1) participated on 3 occasions: slow digestion CHO (S), fast digestion CHO (F), and water (W). Subjects consumed a 50 g dose of either S or F before a 3-hour treadmill run at 57% V[Combining Dot Above]O2max. Variables were assessed at -15, 0, 30, 60, 90, 135, and 180 minutes. Immediately postrun, subjects completed a time-to-fatigue test at 110% V[Combining Dot Above]O2max. There was a significant difference in CHO ox for W vs. F and S (C,1.14; S,1.52; F,1.66 +/- 0.2 g[middle dot]min-1, p < 0.05). Fat ox was significantly higher in S vs. F (S,0.54; F,0.47 +/- 0.08 g[middle dot]min-1, p < 0.05). Exogenous CHO ox was significantly higher in F vs. S (F,0.26; S,0.19 + 0.04 g[middle dot]min-1, p < 0.05). There was a significant difference in average blood glucose for trial (F,94.5; S,97.1 vs. W,88.4 + 2.1 mg[middle dot]dl-1) and time x trial for F vs. S (0 minutes, p < 0.05). There were no significant performance differences. Consumption of a single bolus of CHO beverage before a 3-hour run elicits significant alterations in energy metabolism compared with just water, with S CHO oxidizing significantly more fat than a rapidly digested carbohydrate. These findings suggest that slow-digesting modified starch provides a consistent blood glucose level and sustained exogenous energy supply during a sustained, 3-hour endurance run. Significance was set at p < 0.05.
