Moseley, L., Lancaster, G. I., Jentjens, R. L., Achten, J., & Jeukendrup, A. E. (2002). The effect of time of pre-exercise carbohydrate feedings on metabolism and cycling performance. Medicine and Science in Sports and Exercise, 34(5), Supplement abstract 1145.

This study investigated the metabolic and performance responses of pre-exercise carbohydrate (CHO) feedings. Hypoglycemia might be caused by early ingestion. Ss (N = 8) ingested 75 gm of glucose in 500 ml of water on several occasions. Post-ingestion rest periods of 15, 45, and 75 minutes were experienced before exercising for 20 minutes at 65% Wmax followed by a time trial.

There were no differences in performance or ratings of perceived exertion between the conditions. There were significant differences in plasma glucose between the 15-min and 45 and 75-min conditions. All conditions differed in the amount of insulin at the start of exercise. Those differences disappeared within 10 minutes into exercise. No Ss became hypoglycemic in the 15-min condition while two were slightly hypoglycemic in the 45 and 75-min conditions.

Implication. The occasional experience of hypoglycemia after ingesting pre-performance CHO does not appear to affect aerobic performance.

Return to Table of Contents for this issue.