Effects of Rehydration During Physical Exercise on Acute Kidney Injury Biomarkers

1. Intervention: rehydration with glucose solution. Glucose will be administered at a dose of 35 mg (500 ml of 7% solution) taken orally once, in the middle of soccer training session, at approximately 10.00 a.m. 2. Intervention: rehydration with fructose solution. Fructose will be administered at a dose of 35 mg (500 ml of 7% solution) taken orally once, in the middle of soccer training session, at approximately 10.00 a.m. 3. Intervention: rehydration with xylitol solution. Xylitol will be administered at a dose of 35 mg (500 ml of 7% solution) taken orally once, in the middle of soccer training session, at approximately 10.00 a.m. 4. Intervention: rehydration with sucrose solution Saccharose will be administered at a dose of 35 mg (500 ml of 7% solution) taken orally once, in the middle of soccer training session, at approximately 10.00 a.m.