Temesi, J., Johnson, N., Raymond, J., & O'Connor, H. (June 2, 2010). Performance benefit of carbohydrate ingestion during endurance exercise A systematic review. Presentation 1584 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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This study systematically reviewed the research on carbohydrate ingestion during exercise and performed a meta-analysis to determine the performance benefit of carbohydrate ingestion in accordance with current ACSM guidelines. Relevant databases were searched from inception to October 2009 using combinations of terms related to carbohydrate and exercise performance. To be included, studies needed to be placebo-controlled, randomized, crossover designs; meet current ACSM guidelines for carbohydrate ingestion during exercise; and employ a time-trial or exercise to exhaustion performance measure. Of the 37,354 studies from the initial search, 44 met the inclusion criteria. Within each category of performance trial (time-trial (TT), timed exercise to exhaustion (TTE), submaximal exercise followed by either TT (submax+TT) or TTE (submax+TTE)), standardized mean differences (effect sizes) between carbohydrate and placebo were calculated and analyzed.

The effect size for submax+TT with ingestion of 30-80g carbohydrate per hour was significant (N = 13 studies) translating into a mean improvement in exercise performance of 8.2% favoring carbohydrate ingestion. TT (N = 10 studies) and TTE (N = 19 studies) also showed significant effects. These translated into mean improvements of 1.9 and 15.9% with carbohydrate ingestion for TT and TTE respectively. Similar effects were calculated for ingestion of 30-60 g carbohydrate per hour, except for a non-significant effect for TT (N = 7).

Implication. The ingestion of carbohydrate according to current ACSM guidelines significantly and meaningfully enhances endurance exercise performance.

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