The mechanism of post-exercise hypotension (PEH) is not still established. One of the postulated mechanisms is the lowered pre-load induced by the reduced plasma volume (PV) due mainly to the sweating during the long-lasting moderate exercise. We, therefore, aimed to clarify the effect of prior exercise with and without water intake to post exercise blood pressure. Seven young male subjects performed 60-min cycling exercise at the intensity of 60 % heart rate (HR) reserve following 30-min supine rest, and subsequently kept the supine rest recovery for 60-min, as a control (C) protocol without any water drinking throughout the protocol. Then, as the interventional protocol, i.e. water intake (W) protocol, same exercise was performed with concomitantly oral water intake ad lib (797±116 ml; mean±S.E.M.) to adjust the body weight to that before the exercise onset. Throughout both protocols, HR and arterial blood pressure (BP) were measured. In addition, at the timing of just before and after the exercise, and at 30th and 60th min of recovery, the capillary blood was sampled to estimate the relative change of PV (ΔPV) using by hematocrit and hemoglobin concentration. Mean BP was substantially decreased approximately during the later half of recovery (〜5mmHg) in C protocol, compared to that of the prior-exercise rest. In contrast, BP in W protocol during recovery had no apparent reduction, rather elevation of diastolic BP, and was significantly higher to those of C protocol. The relative changes of PV did not show so much different change during recovery between both protocols, i.e., −17.1±2.2 and −9.8±2.7 % (P<0.05) just after the exercise, −0.6±1.3 and 1.5±3.7 % (P>0.05) at 30th min and −3.1±2.8 and 2.6± 4.7 % (P>0.05) at 60th min of recovery in C and W, respectively. These results indicate that PEH seems to be no direct linkage to the pre-load via PV change, rather the unresolved effect of water intake itself during exercise might have an essential influence to BP of the following resting recovery.

DESCENTE SPORTS SCIENCE Vol.30/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE