Influence of Postexercise Glucose Ingestion upon Serum Potassium Levels and ECG Function

in International Journal of Sport Nutrition and Exercise Metabolism
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Thirteen trained runners were studied to determine whether postexercise glucose ingestion contributes to electrocardiogram (ECG) alterations by enhancing decreases in serum potassium (K+) concentrations. For the two randomly ordered trials, subjects ingested a 100 g (25% w/v glucose polymer) drink, either alone or with the addition of 3 g of potassium chloride (KCI), within 15 min following a 90-min run. ECG parameters, serum K+, and glucose concentrations were measured preexercise (Time 0), 2-3 min postexercise (Time 1), and 25 (Time 2) and 60 (Time 3) min postexercise. The data suggest that postexercise glucose ingestion may cause ECG changes that are not directly related to the return of K+ to muscle, and that these changes, although characteristic of hypokalemia, may be related to serum glucose excursions rather than to absolute levels of serum K+. The addition of KCl may have prevented these changes by delaying gastric emptying of glucose.

H.C. Reynolds, L. Cordain, and S. Linnell are with the Department of Exercise and Sport Science, and M.A. Harris is with the Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, CO 80523. Direct correspondence to L. Cordain.