Reduced aldosterone and sodium excretion in endurance-trained athletes before and during immersion
- 37 Downloads
Aldosterone excretion (AE) and plasma renin activity (PRA) were measured in eight untrained (UT) and eight endurance-trained (TR) male subjects before and during 4 h head-out immersion to study the mechanism of reduced renal sodium excretion in athletes. AE was significantly lower before immersion, and decreased less during immersion, in TR than in UT. Fractional sodium excretion, too, was lower and increased less during immersion in TR than in UT. PRA decreased in the water bath in all subjects (p<0.001) with no significant difference between the groups. During immersion, plasma sodium concentration oscillated whereas potassium concentration showed a temporary rise in TR (p<0.001). The attenuated response of AE in TR may be due partly to this increase of plasma potassium concentration. The generally reduced aldosterone release in TR might be caused by a training induced adaptation of the adrenals to corticotropin. The lowered renal sodium excretion of TR in spite of the decreased AE suggests an intensified aldosterone effect in these subjects, diminishing the salt loss during exercise.
Key wordsAldosterone Renin Electrolytes Physical fitness
Unable to display preview. Download preview PDF.
- Böning, D., Ulmer, H.-V., Meier, U., Skipka, W., Stegemann, J.: Effects of a multi-hour immersion on trained and untrained subjects.: I. Renal function and plasma volume. Aerospace Med.43, 300–375 (1972a)Google Scholar
- Böning, D., Ulmer, H.-V., Meier, U., Stegemann, J.: Effects of a multi-hour immersion on trained and untrained subjects: II. Blood protein and electrolyte concentrations. Aerospace Med.43, 415–418 (1972b)Google Scholar
- Korge, P., Seene, T.: Zur Bestimmung des extrarenalen Natrium- und Kalimverlustes bei Sportlern. Med. Sport12, 204–206 (1973)Google Scholar
- Külpmann, W. R., Siekman, L., Breuer, H.: An improved gas chromatographic method for the determination of aldosterone in urine. Acta Endocrinol. [Suppl.] (Kbh.)159, 34 (1972)Google Scholar
- Sundsfjord, J. A., Stromme, S. B., Aakvaag, A.: Plasma aldosterone (PA), plasma renin activity (PRA), and cortisol (PF) in exercise. In: Metabolic adaptation to prolonged physical exercise, Howald, H., Poortmans, J. R. (eds.), pp. 308–314. Basel: BirkhÄuser 1975Google Scholar