Background: The purpose of this paper was to examine the fate of K+ released from contracting muscles during supramaximal exercise repeated three times, which is known to be associated with a large efflux of K+ and lactate into plasma.Material/Methods: Nineteen healthy students of physical education volunteered for the study. All participants performed 30s Wingate Anaerobic Test three times with 7 min rest break. During the exercise test indices of anaerobic capacity were assessed. Parameters characterizing acid base status and potassium ion concentration in plasma, whole blood and erythrocytes were measured before the exercise test, during each break between bouts and 15 min after the end of the exercise.Results: The result showed that plasma and intraerythrocyte ion potassium concentrations were significantly increased after each bout of exercise, but exercise induced plasma hiperkalemia was levelled during the first 5 min of recovery. Simultaneously, ion potassium concentration increased in erythrocytes, but not in urine. Post exercise potassium excretion to urine was lower during 24 hours of recovery than before the exercise.Conclusions: Obtained results suggest that erythrocytes take part in rapid changes of blood potassium level after extreme exercise. We also considered that the rapid decrease in exercise - elevated K+ concentration in plasma due to their transport to erythrocytes as a prevention of the loss of potassium ion by the renal system.