EFFECT OF INCREASES IN PLASMA LACTATE CONCENTRATION ON INTRAVASCULAR HEOLYSIS DURING EXHAUSTIVE EXERCISE

A study was performed to examine the effect of plasma lactate concentration on intravascular hemolysis during exercise. Seven men performed maximal and submaximal exercise on a cycle ergometer. The maximal exercise was performed as a graded exercise until exhaustion. The mean performance time of the maximal exercise was 15 min and 4 s. The submaximal exercise was performed for 30 min at 50% HRmax. Blood samples were obtained before, immediately after, and one hour after exercise. Plasma lactate concentration, hematocrit (Ht), and serum haptoglobin concentration (Hp) were measured. Hp was corrected by Ht for hemoconcentration and expressed as HpC. Plasma lactate concentration was elevated significantly (p<0.05) immediately after maximal exercise, and returned to the baseline values one hour after exercise, whereas plasma lactate concentration did not change after submaximal exercise. Hp and HpC did not change even after maximal exercise. These results suggest that the elevation in plasma lactate concentration may not affect intravascular hemolysis during exercise.