Superior endurance performance with ingestion of multiple transportable carbohydrates

Med Sci Sports Exerc. 2008 Feb;40(2):275-81. doi: 10.1249/mss.0b013e31815adf19.

Abstract

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(-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.

Conclusion: Ingestion of GF led to an 8% improvement in cycling time-trial performance compared with ingestion of G.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bicycling
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Carbohydrates / metabolism*
  • Drinking
  • Exercise Test
  • Fructose / administration & dosage
  • Fructose / metabolism
  • Glucose / administration & dosage
  • Glucose / metabolism
  • Humans
  • Male
  • Physical Endurance / physiology*
  • Placebos
  • Task Performance and Analysis
  • United Kingdom

Substances

  • Dietary Carbohydrates
  • Placebos
  • Fructose
  • Glucose