Superior endurance performance with ingestion of multiple transportable carbohydrates.
BACKGROUND
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(-1)) and a water placebo on endurance performance.


METHODS
Eight male trained cyclists were recruited (age 32 +/- 7 yr, weight 84.4 +/- 6.9 kg, .VO(2max) 64.7 +/- 3.9 mL.kg(-1).min(-1), Wmax 364 +/- 31 W). Subjects ingested either a water placebo (P), a glucose (G)-only beverage (1.8 g.min(-1)), or a glucose and fructose (GF) beverage in a 2:1 ratio (1.8 g.min(-1)) 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 (approximately 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.min(-1)) and G (2.50 g.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.


CONCLUSIONS
Ingestion of GF led to an 8% improvement in cycling time-trial performance compared with ingestion of G.
Currell
Kevin
K
Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Birmingham, UK.
Jeukendrup
Asker E
AE
D000328:Adult; D001642:Bicycling; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism*; D004326:Drinking; D005080:Exercise Test; D005632:Fructose / Q000008:administration & dosage / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D010919:Placebos; D013647:Task Performance and Analysis; D006113:United Kingdom
D004040:Dietary Carbohydrates; D010919:Placebos; D005632:Fructose; D005947:Glucose