Schabort, E. J., Bosch, A. N., Weltan, S. M., & Noakes, T. D. (1999). The effect of a preexercise meal on time to fatigue during prolonged cycling exercise. Medicine and Science in Sports and Exercise, 31, 464-471.

Ss (N = 7) exercised to exhaustion on a bicycle ergometer at a workload corresponding to an intensity of 70% maximal oxygen uptake (VO2max). On one occasion (FED), Ss consumed a preexercise carbohydrate breakfast (CHO; 100 g CHO) three hours before exercise. On the other occasion (FASTED), Ss exercised after an overnight fast.

Exercise time to fatigue was significantly longer for the breakfast condition (136 14 min) compared to the fasted state (109 12 min). There were no differences between pre- and post-exercise muscle glycogen concentrations, respiratory exchange ratio, carbohydrate and fat oxidation, and lactate and insulin concentrations for the two trials. Insulin concentrations decreased significantly and free fatty acid concentrations increased significantly in all Ss in both trials.

It was concluded that CHO meal ingestion increased time to fatigue with no negative effects ascribed to increased insulin concentrations and decreased free fatty acid concentrations after consumption.

Implication. A CHO breakfast meal increased endurance performance without provoking insulin or free fatty acid problems.

Return to Table of Contents for this issue.