Petteys, C. L., Foster, C., Brice, G., Doberstein, S., & Porcari, J. P. (2003). Effect of pre-exercise feedings on endurance performance. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1663.

This study evaluated the effect of 35 gm carbohydrate consumption 30 minutes before a 40 km cycling time trial. Well-trained cyclists (N = 10) performed an intensive warm-up, ingested either CHO or placebo, and then performed the well-practiced time trial. Water was freely available during the time trial.

There were no differences between the two pre-exercise ingestion conditions for the following variables: time trial performance, mean power output, mean velocity, blood lactate, or blood glucose. Pre-exercise feeding with CHO is effectively neutral which contradicts findings that suggest it is harmful. The difference could be that harmful results are obtained in studies that use time to exhaustion as the performance criterion whereas here, time trial performance was used.

Implication. Pre-time trial CHO ingestion does not affect time trial performance.

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