Introduction: The aim of the present study was to investigate the effect of ingesting a glucose plus fructose drink compared with a glucose-only drink (both delivering carbohydrate at a rate of 1.8 g/min and a water placebo on endurance performance. Methods: Eight male trained cyclists were recruited (age 32 +/- 7 yr, weight 84.4 +/- 6.9 kg, VO2max 64.7 +/- 3.9 mL/kgmin, Wmax 364 +/- 31 W). Subjects ingested either a water placebo (P), a glucose (G)-only beverage (1.8 g/min), or a glucose and fructose (GF) beverage in a 2:1 ratio (1.8 g/min) during 120 min of cycling exercise at 55% Wmax followed by a time trial in which subjects had to complete a set amount of work as quickly as possible (~1 h). Every 15 min, expired gases were analyzed and blood samples were collected. Results: Ingestion of GF resulted in an 8% quicker time to completion during the time trial (4022 s) compared with G (3641 s) and a 19% improvement compared with W (3367 s). Total carbohydrate (CHO) oxidation was not different between GF (2.54 +/- 0.25 g[middle dot]min-1) and G (2.50 g[middle dot]min-1), suggesting that GF led to a sparing of endogenous CHO stores, because GF has been shown to have a greater exogenous CHO oxidation than G. Conclusion: Ingestion of GF led to an 8% improvement in cycling time-trial performance compared with ingestion of G.
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