Renin-angiotensin-aldosterone system and physical exercise.

The renin-angiotensin-aldosterone system plays a primary role in regulating the physiological response and adaptation of fluid-electrolyte balance as well as cardiovascular function to exercise in man. We reviewed the main mechanisms leading to stimulation of the renin-angiotensin-aldosterone axis during physical stress, i.e. the decrease in renal perfusion and in the NaCl load to the macula densa, the enhancement of sympathetic activity, and the reduction in hormone clearance rate. Interpretation of hormonal changes is difficult because of the variability in environmental conditions and exercise protocols, and the different subjects characteristics. We analyzed these confounding variables reported in literature studies, showing their influence on renin-angiotensin-aldosterone response. Possible implications of these hormonal alterations for performance and health, and the evaluation of new mechanisms of hormones regulation, i.e. receptor changes, require further research.