ERYTHROCYTE FREE-RADICAL SCAVENGER ENZYMES IN BICYCLE PROFESSIONAL RACERS - ADAPTATION TO TRAINING

This study was designed to investigate the influence of endurance training on the activities of the scavenger enzymes superoxide dismutase (SOD), catalase (CAT) and glutathion peroxidase (GSH-Px) measured in erythrocytes from sedentary subjects, amateur bicycle racers and in professional bicycle racers who were cycling in two real cyclist contests including the top-class race Vuelta a Espana (VCE). Under resting conditions the SOD activity was higher (p < 0.01) in cyclists than in controls. The activities of CAT and GSH-Px were higher (p < 0.05 and p < 0.01, respectively) under resting conditions in professional cyclists versus measured both in sedentary subjects and amateur cyclists. The enzyme activities were not modified significantly in professional cyclists after a bout of exercise of 22 km in 5 hrs, but the SOD activity was increased (p < 0.05) and CAT activity reduced (p < 0.05) after 2800 km in 20 days (VCE). The present results shown that aerobic endurance training, when at a professional level, produces an increase in the erythrocyte activities of the main free radicals scavenger enzymes.