THE EFFECT OF PHYSICAL CONDITIONING ON ANTIPYRINE CLEARANCE

The effects of physical conditioning on antipyrine clearance were stud ied in two groups of subjects. Healthy men not engaged in the systemat ic practice of any sport were compared with endurance runners (defined as men running > 80 km/week). Studies were carried out at three diffe rent periods of the annual plan training at 4-month intervals, Antipyr ine was administered orally and pharmacokinetic parameters were obtain ed from saliva samples by the multiple-sample method. Endurance perfor mance, expressed in terms of the maximal oxygen uptake ((V) over dot O -2max), the ventilatory threshold and the 4-mM . l(-1) lactate thresho ld (OBLA), was higher in trained than in control subjects at each of t he three periods. Antipyrine clearance was also significantly elevated and antipyrine half-life reduced in runners during all periods. No si gnificant difference in (V) over dot O-2max or antipyrine clearance wa s found between the various periods in either trained or control subje cts, Both ventilatory threshold and OBLA increased significantly along the training period in conditioned subjects. Significant correlations were found between antipyrine clearance and (V) over dot O-2max, vent ilatory threshold and OBLA. In summary these results indicate an assoc iation between aerobic conditioning and increased hepatic oxidative me tabolism of low-clearance drugs.