Carbohydrate/electrolyte drinks: effects on endurance cycling in a warm environment

ABSTRACT On three occasions cyclists completed, as fast as possible, two exercise tasks (T1 and T2) separated by 30 mm rest. T, and T2 were equivalent to the work performed during 2 h cycling at 75 % VO2max and 30 mm at 75 % VO2max, respectively. Every 20 mm subjects drank 275 mL ofa 6 % (MC) or 2.5 % (LC) carbohydrate-electrolyte beverage or a water placebo (F). The initial drink during both T1 and the rest period contained 20 g D20 as a marker for entry of ingested fluid into blood. No differences in drink effects were found for heart rate, sweat rate, change in plasma volume, rectal temperature, or D2O accumulation in blood. Blood glucose and respiratory exchange ratios were higher and T2 was performed faster with MC than with P. Ingestion of MC can help maintain blood glucose and enhance performance of prolonged cycling exercise without compromising fluid replenishment. Am J C/in Nutr 1988;48: 1023-30. KEY WORDS Fluid replenishment, deuterium oxide (D20) accumulation, temperatur