Effect of Oral Prednisolone on Sport Performance and Urine Doping Test

The purpose of this study was to investigate that the effect of oral administration of prednisolone (Pred) on the changes of urine Pred concentrations following a single bout of exercise and to determine the sport performance in young men. Seven healthy male volunteers (age, 19.6 ± 1.0 yr; height, 170.1 ± 2.8 cm; weight, 65.5 ± 2.3 kg) with regular exercise activities were participated in this study. All subjects were undertaken three different treatment trials. In the first trial, subjects received 5 mg Pred with 400 mg maltodextrin, and then urine Pred concentration was estimated during 24 hours (PredC). In the second and third trials, subjects were assigned into either placebo (400 mg maltodextrin) with exercise (PLE) or Pred (5 mg plus 400 mg maltodextrin) with exercise (PredE) trials. A 70% VO2max endurance exercise test to exhaustion was performed immediately after supplementation. Respiratory related markers, blood sample and 24 hours urine prednisolone concentrations were measured. The results showed that there was no significant difference in the urinary Pred concentration between PredC and PredE trials during 24 hours. The urinary Pred concentration in PredC trial at 12 hours was below 30 ng/ml, while, it was above 30 ng/ml in PredE trial at the same time point. No significant differences in respiratory related markers, rate of energy utilization and exercise time to exhaustion were observed between PLE and PredE trials. The concentration of blood free fatty acid at 15 min during exercise was significantly lower in PLE than PredE trial. The blood glucose level in PLE was significantly lower than PredE trial at 45 min and 60 min during exercise, and also immediately after exercise. The main finding of this study was that sub-maximal exercise may not accelerate urinary elimination rate of Pred, and may cause positive test result after 12 hours in young men. Besides, ingestion of low-dose Pred could not increase the time to exhaustion during the sub-maximal exercise test.