Kirwan, J. P., O'Gorman, D., Campbell, D., Sporay, G., & Evans, W. J. (1996). A low glycemic meal 45 minutes before exercise improves performance. Medicine and Science in Exercise and Sports, 28(5), Supplement abstract 768.

Whether foods with a high soluble fiber content and low glycemic index optimize glucose availability and improve performance were evaluated. Active females (N = 6) ate 75 gm of available carbohydrate (CHO) in the form of breakfast cereals (sweetened whole grain rolled oats (RO) or sweetened whole oat flour (OF) and 300 ml of water) or water alone (CON). These were consumed 45 minutes prior to performing semi-recumbent cycling exercise to exhaustion (intensity of 60% VO2max). Blood free-fatty acids (FFA), glycerol, insulin, epinephrine, norepinephrine, and muscle glycogen (through biopsies of vastus lateralis) were measured before the meal and after exercise. Diet was controlled by having Ss reside under supervision for 3 days before each trial.

At 90 and 120 min of exercise, plasma FFA levels were lower in the RO and OF conditions than CON. At exhaustion there was do difference between conditions in the measures. The RO trial produced enhanced performance when compared to the CON trial. OF performance was similar to CON performance.

Implication. Eating a meal with a high soluble fiber content and low glycemic index 45 minutes prior to a prolonged moderately intense level of exercise enhances performance.

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