Plasma vasopressin, renin activity, and aldosterone: effect of exercise and training

The influence of endurance-training on hematocrit, plasma vasopressin, renin activity, and aldosterone changes at rest and at the end of an exercise performed until exhaustion at a given and constant relative work-load (87% of maximal oxygen uptake) has been studied in four untrained subjects submitted to a 5-month training. At the end of this period, maximal oxygen uptake increased of 15.2% (p less than 0.01). Hematocrit at rest slightly rose after training, and if exercise constantly induced increases in hematocrit before (p less than 0.001) and after training (p less than 0.005), the per cent increase after training was lower than before (p less than 0.05). Comparison between the importance of weight loss and hematocrit variation showed that when untrained subjects become trained the variation of hematocrit after exercise becomes smaller while weight loss is more important (p less than 0.01). Plasma renin activity (PRA), aldosterone (Aldo) and vasopressin (AVP) levels, compared to control values, displayed a significant increase after exercise before as well as after training. Control values remained unchanged after training for aldosterone and AVP, but were significantly lower (p less than 0.05) for PRA. This latter observation could be explained by the change in blood volume induced by exercise.