THE INFLUENCE OF PREEXERCISE GLUCOSE-INGESTION ON ENDURANCE RUNNING CAPACITY

Drinking a concentrated glucose solution less than Ih before the start of prolonged submaximal exercise has been reported to reduce endurance capacity during cycling. The purpose of this study was to re-examine the influence of pre-exercise ingestion of a concentrated glucose solution on endurance running capacity. Nine recreational runners (five men and four women) ran to exhaustion on a level treadmill, at speeds equivalent to 70% Vo(2max), on two occasions separated by at least 1 week. The runners ingested either a solution containing 75g of glucose in 300ml of water (G trial), or 300ml of sweetened water (P trial) 30 min before each trial. As a consequence, the blood glucose concentrations were 55% higher at the beginning of the G trial compared with those recorded for the P trial (G trial, mean(s.e.) blood glucose = 6.3(0.7) mmol l(-1) versus P trial, mean(s.e.) blood glucose = 4.1(0.3) mmol l(-1); P < 0.01). Nevertheless, there were no differences in the running times to exhaustion between the two trials (G trial, mean(s.e.) 133.79(11.0) min versus P trial, mean(s.e.) 121.16(8.1) min). The results of this study show that ingesting a 25% glucose solution 30 min before exercise does not reduce the recreational runners when the equivalent to 70% Vo(2max).