Renal function parameters during early and late recovery periods following an all-out 21-km run in trained adolescent runners

Background: This study investigated the changes in biomarkers of renal function and the corresponding estimated glomerular filtration rate (eGFR) in 10 male adolescent (16.2±0.6 years) trained runners during early and late recovery periods after an all-out 21-km run. Methods: Venous blood samples were taken immediately before, and at 2-h, 4-h, and 24-h following the 21-km run. Samples were analyzed for hemoglobin (Hb) and hematocrit (Hct), and serum urea (U), creatinine (Cr), creatine kinase (CK) and lactate dehydrogenase (LDH). U/Cr ratio, eGFR, and plasma volume change (%ΔPV) were calculated based on the associated measured variables. Results: At 2-h and 4-h, there were increases (26%-146%) in U, Cr, U/Cr, CK, and LDH, and decreases (8%-13%) in Hb and Hct, as compared with the corresponding pre-exercise values. The calculated %ΔPV increased by 17% while the eGFR decreased 20% from the corresponding pre-exercise value, respectively. At 24-h, the changes of the blood variables and renal function parameters observed at early recovery period were sustained. Conclusions: Taken together, the findings of this study suggest that mild decline in renal function occurred during the early recovery period following the 21-km run. The decline in renal function did not return to normal during the later recovery period.