Hydration is recommended in order to decrease the overload on the cardiovascular system during endurance exercise. The amount of water that an individual may consume is often restricted during mountaineering. Fifteen hypertensive (resting systolic blood pressure, SBP≥140 mmHg and/or diastolic blood pressure, DBP≥90 mmHg) and 8 normotensive (NT) volunteers, aged 64.0±4.2 yr, participated in mountain hiking (elevation 935.9 m) to determine whether or not a sufficient amount of water was normally consumed in order to prevent the effects of dehydration. The hyperetensive subjects were divided into two groups at random. One group took water freely (8 hypertensive group: HT), while the other group were told to consume 4000ml of water (7 hypertensive supplied water group: HT-W) while hiking. The NT group consumed water freely. All subjects were members of an alpine club and thus had some experience in mountaineering. The SBP and DBP, body weight, and specific gravity of the urine were all measured before and after hiking. In addition, the subjects recorded their blood pressure (BP) at 10 measurement points designated along the climbing route. The heart rate (HR) was recorded every minute continuously during mountaineering. The total climb took about 7 hours, there were no differences in the time between three groups. The amount of water which subjects drank were HT-W 4000ml, NT 1138±366ml, HT 1450±832ml, respectively. The average change in body weight from before hiking was -1.0±0.7kg in NT, -1.1±0.4kg in HT, and -0.1±0.7kg in HT-W after hiking, respectively. There was a significant difference between the HT-W and the other groups (p<0.05). Repeated measures ANOVA exhibited a main effect among the groups regarding the HR responses (HT>HT-W>NT). Repeated measures ANOVA exhibited a main effect among the groups and the BP responses (HT-W>HT>NT). Our findings suggested that dehydration during mountaineering in hypertensive trekkers may thus result in an inability to maintain cardiac output due to a reduced blood volume when only consuming water freely. In conclusion, it is important for hypertensive elderly trekkers to maintain their hydration levels by sufficient fluid replacement during mountaineering.

DESCENTE SPORTS SCIENCE Vol.27/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE