As an index of bodily adaptation development for muscular exercise two groups of subjects (T-group, trained, and U-group, untrained) were studied under a fixed environmental condition. All the member of T-group responded with quicker rises in the sweat rate, as if their bodies anticipated and took measures against the impending rise of body temperature, and attained early at the individual steady levels, in moderate or low load exercise ; moreover their Cl losses in the sweat were remarkably low, thus effectively keeping the internal environment of the body (this time the ion concentration of the blood) less disturbed. Together with other findings, we infer that physical training sets our body more efficient in dealing with the excessive heat produced by muscular exertion.

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.

To study the age difference in sweating during muscular exercise, two series of experiments were conducted under constant climatic conditions (29 ± 1°C DB, 60 ± 5 % RH, 0.45±0.05 m/sec air flow) . In series A, 7 to 20 years old male subjects undertook 5-minute running or pedalling of a bicycle ergometer in various seasons. In this series of experiments, pectoral sweat volume, sweat chloride concentration, rectal and mean skin temperatures were in general determined every 5 minutes and, when necessary, the total body sweat volume was calculated from the body weight loss. In series B, the age difference in the sweating in relation to physical training was studied. Subjects, 3 to 20 years old received experimental physical training of 5-minute or 500m-running. Before and after the training, a work load of 3- or 5-minute outdoor running was assigned to them. Furthermore, before and after the training, 10 and 11 years old subjects were given a fixed mechanical work rate on a bicycle ergometer. In these experiments, most of the parameters described above were measured. In series A, age differences in sweating during exercise were noticed to be dependent on the intensity of work load between pre- and post-adolescents. When the work load was heavy enough to cause a rapid increase in rectal temperature, the sweat volume became significantly less, the mean skin temperature was far higher, and the sweat chloride concentration was remarkably smaller in the pre-adolescent subjects than in the post-adolescent ones. In series B, an age difference in the effect of physical training was also found on sweating during exercise. The effect of physical training on sweating in the pre-adolescent individuals was generally less significant than in adults and sometimes showed a different pattern from that of adults. From these results, it can be concluded that sweating in the pre-adolescents is less adaptive, particularly to continuous severe exercise and that physical training is less effective in them than in the post-adolescents.