Stimuli for aldosterone secretion during an intense, long duration physucak activity

Abstract

Objective: To establish the possible causal factors of aldosterone secretion during an intense, long duration physical activity, under neutral environmental conditions in nine long-distance runners.

Methods: After a 10-minute warm-up period on a treadmill, 1% grade and at 55% of PWCmax, followed by 90 minutes test in six stages, at 80% of PWCmax, there was a final 90 minute passive recovery period. No water was replenished during the dehydration procedure (DH) but during rehydration (RH) 51% of the body weight lost during the DH procedure was replaced.

Results: In the DH phase weight loss and reduction of the relative plasmatic volume (%VP) were found. Blood osmolarity, potassium, sodium and aldosterone concentrations were increased, whereas renin concentration was normal. When hemoconcentration correction was done and change percentage of variables was calculated, only potassium and aldosterone concentrations were increased. There was less body weight loss during RH compared to DH period, whereas plasmatic osmolarity and sodium concentration did not increase. Potassium concentration increased during excercise and aldosterone concentration increased in both excercise and recovery periods. Similar results were found with hemoconcentration correction.

Conclusions: Plasmatic aldosterone concentration increased proportionally to excercise duration and was not related to reduction of plasmatic volume during an intense physical activity. Aldosterone hypersecretion seems to be the result of multiple factors, and potassium concentration was one of them.