A study was conducted to determine the effect of water running exercise (WRE) on renal function. The study involved 5 healthy males who performed maximal work by both WRE and bicycle ergometer exercise (BEE), and 6 males who performed head-out water immersion.
The results obtained were as follows;
1) The values of VO₂max and maximum heart rate (HRmax) during WRE and BEE were approximately similar, and blood lactate concentration after exercise was significantly higher then the basal value in both types of exercise, although the value was significantly higher after WRE than after BEE.
2) Compared with the resting values on land, significant decreases in HR and plasma aldosterone (Ald) concentration were noted in head-out water immersion, but plasma antidiuretic hormone (ADH) concentration and urinary volume were not changed significantly from the resting values.
3) The secretion of both plasma ADH and Ald was significantly increased at the end of both types of exercise. However, a larger increase in Ald and ADH was observed after BEE than after WRE.
4) The rate of urine flow was obviously decreased soon after both types of exercise; this was positively correlated with changes in creatinine clearance and negatively correlated with changes in Ald concentration.
The results of the present study suggest that a better venous return is induced by the water pressure and cardiac output during WRE, possibly inducing the release of atrial natriuretic fsctor (ANF) . ANF may inpair the release of ADH and Ald to a greater extent in WRE than in BEE.