Renal Excretion of Lactic Acid in Exercise

Abstract

Blood lactate concn. and total urine lactate during exercise and recovery were detd. in 72 expts. on 2 subjects. The expts. covered a wide range of blood lactate concns. and urine flow rates. The data support the concept that lactate is filtered in the glomeruli and variably re-absorbed in the tubules. The apparent renal threshold is approx. 60 mg.%, but small amts. of lactate appear in the urine at blood concns. below this threshold. The lactate clearance is 1-2 ml./ min. at rest and rises to 15-20 ml./min. in exhausting exercise. The clearance is increased during water diuresis. Urine lactate is only an approx. index of total lactate production in exercise, due probably to variability in the renal threshold and in the renal blood flow changes in exercise in different subjects and in the same subject at different times.