Age-specific features in renal response to food intakes and training loads in young professional skiers

Abstract

The age-specific features of renal functions have been studied in older adolescents and young adults training in ski racing before and after their water and food intake and training loads. Baseline renal functions in the morning demonstrated higher glomerular filtration rate (GFR) and more mature development of the osmoregulatory mechanisms (higher excretion of osmotically active substances, osmotic concentration index, and reabsorption of solute-free liquid) in young adults, compared with adolescents. After food intake, the osmoregulatory mechanisms provided in young adults an adequate renal response—increased excretion of ions in exchange for urea, which preserves osmolality. At the same time, increased excretion of osmotically active substances synchronously with growth in the rate of urine output, higher GFR and reabsorption of solute-free liquid was marked in adolescents, which points to less mature development of the osmoregulatory system. The similar trend of renal homeostatic responses after physical training indicated the activation of volume regulatory mechanisms which did not differ between age groups. Our conclusion is that the definitive volume regulation develops ahead of osmoregulation.