ABSTRACT
A study was designed to examine the effects of exercise intensity on renal clearance parameters. Five healthy male subjects underwent exercise tests on an bicycle ergometer at 4 different work loads for 15 min. The indicators of exercise intensity employed were the percentage of maximal oxygen uptake (%VO<SUB>2</SUB>max), heart rate (HR) and blood lactate level (La) . As parameters of renal clearance, para-aminohippurate clearance (CPAH), thiosulfate clearance (C<SUB>thio</SUB>) and creatinine clearance (C<SUB>cr</SUB>) were measured by the continuous infusion technique during the exercise.<BR>1) The renal clearance parameters during exercise decreased linearly as the exercise intensity increased. The percentage of maximal oxygen uptake at the onset of the decreases in %C<SUB>PAH</SUB>, %C<SUB>chiu</SUB> and %C<SUB>cr</SUB> were 36, 45 and 47%VO<SUB>2</SUB>max, respectively.<BR>2) Among the indicators of exercise intensity, the decrease in La showed the closest correlation with renal clearance during the exercise.<BR>3) The renal plasma flow, which was measured as C<SUB>PAH</SUB>, began to decrease linearly at a significantly lower exercise intensity than the glomerular filtration rate, which was measured as both C<SUB>thio</SUB> and C<SUB>cr</SUB>.<BR>The above results suggest that renal clearance parameters begin to decrease at the threshold as exercise intensity increases.