[Effect of physical exercise on glycolysis in human red blood cells (author's transl)]

Untrained healthy male volunteers were studied to observe the effects of physical exercise (bicycle ergometer, 920 kpm/min for 10 min, 15 min and 30 min) upon glycolytic intermediates in red blood cells. The levels of glucose 6-phosphate, fructose 6-phosphate, pyruvate and lactate increased after each exercise. The levels of fructose 1,6-diphosphate increased and phosphoenolpyruvate decreased respectively only after 30 min of exercise. At the rest period of 30 min after 30 min of exercise the lactate level still remained unchanged, however all the other intermediates returned to the preexercise values. A negative crossover point seemed to exist between fructose 6-phosphate and fructose 1, 6-diphosphate after 15 min of exercise. A positive crossover point was observed between phosphoenolpyruvate and pyruvate after 30 min of exercise. There were significant increases in hexokinase and pyruvate kinase activities, but not in phosphofructokinase activity after 30 min of exercise. These facts suggested that the increase in pyruvate kinase activity was due to the elevated fructose 1,6-diphosphate level after 30 min of exercise. A significant increase in plasma dopamine-beta-hydroxylase activity was found after each exercise. A close positive correlation was observed between pyruvate-phosphoenolpyruvate ratio and dopamine-beta-hydroxylase activity after 30 min of exercise. It was suggested that pyruvate-phosphoenolpyruvate ratio provided a reliable index of physical exercise.