The use of carbohydrates during exercise as an ergogenic aid.

N.M. Cermak, L.J.C. van Loon*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Carbohydrate and fat are the two primary fuel sources oxidized by tissue during prolonged (endurance-type) exercise. The relative these fuel sources largely depends on the exercise intensity and greater contribution from carbohydrate as exercise intensity is Consequently, endurance performance and endurance capacity are largely by endogenous carbohydrate availability. As such, improving carbohydrate availability during prolonged exercise through carbohydrate ingestion dominated the field of sports nutrition research. As a result, it has well-established that carbohydrate ingestion during prolonged (>2 h) moderate-to-high intensity exercise can significantly improve endurance performance. Although the precise mechanism(s) responsible for the effects are still unclear, they are likely related to the sparing of muscle glycogen, prevention of liver glycogen depletion and subsequent development of hypoglycemia, and/or allowing high rates of carbohydrate oxidation. Currently, for prolonged exercise lasting 2-3 h, athletes are to ingest carbohydrates at a rate of 60 g.h-1 (~1.0-1.1 g.min-1) to maximal exogenous glucose oxidation rates. However, well-trained athletes competing longer than 2.5 h can metabolize carbohydrate up to (~1.5-1.8 g.min-1) provided that multiple transportable carbohydrates ingested (e.g. 1.2 g.min-1 glucose plus 0.6 g.min-1 of fructose). small amounts of carbohydrate ingestion during exercise may also enhance performance of shorter (45-60 min), more intense (>75 % peak oxygen VO2peak) exercise bouts, despite the fact that endogenous carbohydrate unlikely to be limiting. The mechanism(s) responsible for such ergogenic properties of carbohydrate ingestion during short, more intense exercise has been suggested to reside in the central nervous system. Carbohydrate ingestion during exercise also benefits athletes involved in sports. These athletes are advised to follow similar carbohydrate strategies as the endurance athletes, but need to modify exogenous intake based upon the intensity and duration of the game and the endogenous carbohydrate stores. Ample carbohydrate intake is also those athletes who need to compete twice within 24 h, when rapid endogenous glycogen stores is required to prevent a decline in support rapid post-exercise glycogen repletion, large amounts of carbohydrate (1.2 g.kg-1.h-1) should be provided during the acute from exhaustive exercise. For those athletes with a lower threshold for carbohydrate ingestion immediately post-exercise, and/or muscle re-conditioning, co-ingesting a small amount of protein (0.2-0.4 g.kg-1.h-1) with less carbohydrate (0.8 g.kg-1.h-1) may provide a to achieve similar muscle glycogen repletion rates.
Original languageEnglish
Pages (from-to)1139-1155
JournalSports Medicine
Volume43
Issue number11
DOIs
Publication statusPublished - 1 Jan 2013

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