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<0.01). Hematocrit at rest slightly rose after training, and if exercise constantly induced increases in hematocrit before (p<0.001) and after training (p<0.005), the per cent increase after training was lower than before (p<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<0.01).