PS-C25-3: THE EFFECT OF MOUNTAINEERING ON THE ASSOCIATION BETWEEN BLOOD PRESSURE AND PHYSICAL ACTIVITY. THE MOUNT FUJI STUDY

Abstract

Objective: It has not been fully investigated whether the response of blood pressure (BP) to activity at high altitudes differs from that at low altitudes or how temperature is involved in these differences. We hypothesized the BP response to activity during mountaineering would be increased compared to that in daily living, and conducted this study to compare physiological BP response to accelerometer measurements during mountaineering and daily living. Design and method: In 15 healthy people (mean age 33 ± 6 years), a new multi-sensor ambulatory BP monitoring (ABPM) device equipped with barometer, thermometer, and accelerometer was used to measure blood pressure responses to activity during a trip to Mt. Fuji and during daily life at low altitudes on another day. Associations between physical activity (log-transformed 5-min average values of accelerometer just before each ambulatory BP) and the corresponding BP were obtained from 843 and 676 readings during the Mt. Fuji trip and daily living, respectively. Result: All ambulatory systolic BP (SBP) parameters were significantly higher during the Mt. Fuji trip than during daily living at low altitudes (all p < 0.01). There were significant positive correlations between physical activity and corresponding BPs in both mountaineering and daily living (all P < 0.01), and there was an interaction between BPs and physical activity according to the two conditions (P < 0.01). On Mt. Fuji, multivariate regression analysis showed that increased physical activity and lower temperature were associated with increased 24-hr SBP and diastolic BP (DBP) (all P < 0.05). The goodness-of-fit values of the association between activity and 24-hr SBP or DBP were improved by adding temperature to the model of both 24-hr SBP and DBP. However, these associations were not found in the daily living model. Conclusions: BP response to activity was more pronounced during mountaineering than daily living. Lower temperature compounded the BP response to activity in the mountains but not in daily living.