King Grub
2013-05-23, 12:35
Recent studies have demonstrated a direct link between increased exogenous CHO oxidation (CHOexog) and enhanced performance. The limiting factor for CHOexog appears to be at the level of intestinal transporters, with sodium/glucose cotransporter 1 (SGLT1) and glucose transporter type 5 (GLUT5) responsible for glucose and fructose transport, respectively. Studies in animal models have shown that SGLT1 and intestinal glucose uptake are up-regulated by high carbohydrate diets or non-caloric sweeteners. The aim of this study was to determine the effect of pre-exercise ingestion of non-caloric sweeteners on CHOexog during exercise in athletes. In a randomized, cross-over, double-blind fashion twenty-three healthy male cyclists (age=29±7yrs, mass=73.6±7.4kg, VO2peak=68.3±9.3 ml/kg/min) consumed 8 x 50ml doses of either placebo (CON) or 1mM sucralose (SUCRA) every 15 min starting 120 min before the onset of exercise. This was followed by 2h of cycling at 48.5±8.6% of VO2peak with continual ingestion of a maltodextrin drink (1.2g/min; 828ml/h). Average CHOexog during the first hour of exercise did not differ between SUCRA and CON conditions (0.226±0.081 g/min vs. 0.212±0.076 g/min, Δ=0.015 g/min, 95%CI -0.008 g/min, 0.038 g/min, p=0.178). Blood glucose, plasma insulin and lactate, CHO and fat substrate utilization, heart rate, ratings of perceived exertion, and gastro-intestinal symptoms did not differ between conditions. Our data suggest that consumption of non-caloric sweeteners in the immediate period prior to exercise does not lead to a significant increase in CHOexog during exercise.
Int J Sport Nutr Exerc Metab. 2013 May 20. Effects of Pre-Exercise Sucralose Ingestion on Carbohydrate Oxidation During Exercise.
Int J Sport Nutr Exerc Metab. 2013 May 20. Effects of Pre-Exercise Sucralose Ingestion on Carbohydrate Oxidation During Exercise.