Measurements of heart rates during usual activities, maximal aerobic power and skinfold thickness were carried out as a basic research for the comparative study of the optimal load for successful living in modern society or in future ages. 18 urban sedentary male workers who came to work by car and were 19-38 years of age were selected as subjects. The mean and S.D. of the maximal aerobic power was 35.8±5.2ml/kg/min, and those of 15 subjects (83%) were below 40ml/kg/min. The means of 12-hr heart rates during usual activities ranged within 71.5-95.0 beats/min. The mean and S.D. of the maximal heart rate during usual activities was 113±10 beats/min; 61±4% of their maximal heart rates during exhaustive exercises. Significant correlation was found between the maximal heart rate during usual activities and maximal aerobic power.
A study was performed to elucidate the effect of physical training on the cold tolerance in human beings. Physically well trained men (T group) and untrained ones (U group) were exposed to cold stress in summer and winter. Each subject was dressed in experimental clothes and exposed to 10°C DB for 60 minutes in both seasons. Moreover, he was exposed in the semi-nude to 20°C DB in summer and to 17°C DB in winter for 60 minutes. During the period of exposure to cold, rectal and mean skin temperatures and respiratory metabolic rate were measured. To confirm the training effect further, the untrained men were asked to follow an experimental training program of daily routine which consisted of about 7 km outdoor running for 40 consecutive days in July and August. Before and after the training, they were exposed to the same cold stress as in the aforementioned summer experiments and subjected to the same measurement. Resting metabolic rate was higher in the T group than in the U group. Although no significant group differences were shown in the metabolic rate during the period of exposure to cold, the rate of increase from the resting value was lower in the T group than in the U group. There were no group differences in rectal or mean skin temperature during this period. When the untrained men were subjected continually to physical training, the resting metabolic rate was higher and the rate of increase from the resting value during the period of exposure to cold lower after the training than before. It was concluded that physical training could be a means to increase the cold tolerance.