Studies on Human Adaptability to Climatic Conditions Reprt 7

Abstract

This study was undertaken to investigate the level of basal metabolic rate (BMR) and its seasonal variation in people living in Okinawa. Determination of BMR was conducted in summer and winter during 1972 and 1973 on the same subjects consisting of 39 natives of Okinawa and 22 natives of the Japanese mainland. The results obtained were as follows:1) It was observed that the skinfold thickness and fat tissue mass were lower in the subjects native of Okinawa than in those native of the Japanese mainland (Table 1, 2). Whereas, BMR in natives of Okinawa was almost the same as that in natives of the mainland, and both were compatible with the Japanese BMR standard reported by the Ministry of Health and Welfare (Fig. 1).2) In agreement with the results of past experimental studies on Japanese, BMR of residents in Okinawa showed seasonal variations, being low in summer and high in winter (Fig. 1, Table 3). The mean variation rate of all the subjects in terms of the annual mean of BMR was 3.2%.3) Seasonal variation rate was higher in office workers with uncomplete cooling system than in those who worked and lived in airconditioned rooms (Maritime Self-Defence Force personnel) or in those receiving hard physical training (Police school students). (Table 6).4) The seasonal variation range of the outdoor temperature was about 27.99°C∼16.76°C in Okinawa and 27.16°C∼6.43°C in the Japanese mainland according to the data of the Weather Bureau. The seasonal variation range in the present study was compared to those obtained in mainland as follows;From the results reported recently in Sasebo and Nagasaki, both in mainland, by Yosida and Chen, respectively, the variation range of BMR in two months with the temperature comparable to the summer mean (27°C)and the winter mean (17°C) in Okinawa, was calculated by the present auther as ±2.6% This figure is almost the same as the value of 3.2% in summer and winter for the residents in Okinawa, obtained by the author.In view of the results of the present study, it is suggested that the range of seasonal variation of BMR for the Southwest Japanese people is controlled by the annual range of the outdoor temperature and their living environmental temperature, irrespective of Okinawa and the Japanese mainland.