Wong, S. H., Lok, A., & Morris, J. (2003). Influence of pre-exercise carbohydrate meals on a 21-km run. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1663.

This study investigated the effect of pre-exercise low and high glycemic index carbohydrate meals on running performance. Male endurance runners (N = 8) completed two trials separated by at least seven days. Two hours before the level treadmill run, Ss consumed an isocaloric meal of low (GI = 37) or high (GI = 77) carbohydrate foods of a weight equivalent to 1.5 gm per kg of body weight. Ss were required to run at 70% VO2max for the first 5-km of the task.

All Ss performed a faster time after the low glycemic index meal. Compared to the high glycemic index condition, carbohydrate oxidation was 9.5% lower and fat oxidation 17.9% higher during low glycemic trial.

Implication. Endurance running performance is likely to be improved if a low glycemic index meal is consumed two hours before exercise.

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