Lactate, Fructose and Glucose Oxidation Profiles in Sports Drinks and the Effect on Exercise Performance

Exogenous carbohydrate oxidation was assessed in 6 male Category 1 and 2 cyclists who consumed CytoMax (TM) (C) or a leading sports drink (G) before and during continuous exercise (CE). C contained lactate-polymer, fructose, glucose and glucose polymer, while G contained fructose and glucose. Peak power output and VO2 on a cycle ergometer were 408+/-13 W and 67.4+/-3.2 mlO(2).kg(-1).min(-1). Subjects performed 3 bouts of CE with C, and 2 with G at 62% VO(2)peak for 90 min, followed by high intensity (HI) exercise (86% VO(2)peak) to volitional fatigue. Subjects consumed 250 ml fluid immediately before (-2 min) and every 15 min of cycling. Drinks at -2 and 45 min contained 100 mg of [U-C-13]-lactate, -glucose or -fructose. Blood, pulmonary gas samples and (CO2)-C-13 excretion were taken prior to fluid ingestion and at 5,10,15,30,45,60,75, and 90 min of CE, at the end of HI, and 15 min of recovery. HI after CE was 25% longer with C than G (6.5+/-0.8 vs. 5.2+/-1.0 min, P<0.05). (CO2)-C-13 from the -2 min lactate tracer was significantly elevated above rest at 5 min of exercise, and peaked at 15 min. (CO2)-C-13 from the -2 min glucose tracer peaked at 45 min for C and G. (CO2)-C-13 increased rapidly from the 45 min lactate dose, and by 60 min of exercise was 33% greater than glucose in C or G, and 36% greater than fructose in G. (CO2)-C-13 production following tracer fructose ingestion was greater than glucose in the first 45 minutes in C and G. Cumulative recoveries of tracer during exercise were: 92%+/-5.3% for lactate in C and 25+/-4.0% for glucose in C or G. Recoveries for fructose in C and G were 75+/-5.9% and 26+/-6.6%, respectively. Lactate was used more rapidly and to a greater extent than fructose or glucose. CytoMax significantly enhanced HI.