INFLUENCE OF POSTEXERCISE GLUCOSE-INGESTION UPON SERUM POTASSIUM LEVELS AND ECG FUNCTION

Thirteen trained runners were studied to determine whether postexercis e glucose ingestion contributes to electrocardiogram (ECG) alterations by enhancing decreases in serum potassium (K+) concentrations. For th e two randomly ordered trials, subjects ingested a 100 g (25% w/v gluc ose polymer) drink, either alone or with the addition of 3 g of potass ium chloride (KCl), within 15 min following a 90-min run. ECG paramete rs, serum K+, and glucose concentrations were measured preexercise (Ti me 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 hypok alemia, may be related to serum glucose excursions rather than to abso lute levels of serum K+. The addition of KCl may have prevented these changes by delaying gastric emptying of glucose.