Changes in Renal Parameters during a Training Camp among Handball Players in the Sub-Saharan Environment

The aim of the study was to describe the changes in kidney parameters induced by 10 days of tapering (TP) during a training camp (TC), where the players were preparing for a group competition, in 15 female handball team members of a Division 1 Amateur of Benin, in the sub-Saharan environment. Measures were taken in all the players before and after the intensive training (IT) and tapering (TP) phases in an intervention study. The estimated glomerular filtration rate (eGFR) with the CKD-EPI 4-level race formula, the fractional excretions of sodium (FeNa) and potassium (FeK), the urine potassium-to-sodium ratio (Na/K urine), and the hemoglobin rate [Hb] were determined for all participants. At the end of IT, eGFR and FeNa increased, respectively, by 22.39% (P < 0.01) and 143.85% (P < 0.01), but the variation of FeK is not significant (P > 0.05). The number of abnormally low eGFR values (<90 mL/min/1.73 m²) was reduced from 11 to 5 (P < 0.05). At the end of TP, the eGFR and urine Na-to-K ratio remained on average constant (P > 0.05) but FeNa decreased by 96.32% (P < 0.001) and FeK increased by 144.41% (P < 0.001). The [Hb] rate increased by 9.80% (P < 0.001), and players had inadequate hydration practice. The results suggested that in addition to its already known effects, TP preserves the positive effects of IT on glomerular function in athletes preparing for a competition that presents a major challenge.