The objects were members of a rescue team of a certain ferrous sulfide mine who were engaged in heavy training under high temperature and humidity. In this experiment, they were put to work under the same intensity of labour, carrying blocks (12 Kg) between the same distance wearing closed life saving masks (weighing about 13.2 Kg). Thus comparing the different environmental conditions between the inside and outside of the mine, changes of physiological responses and relative metabolic rate (R. M. R.) were investigated.
In the mine, the air temperature and also humidity were very high (mean value were 38.3°C and 89.9% respectively), but outside, the air temperature was high (32.7°C) but humidity rather low (67.5%).
The results were as follows:
1. Pulse pressure increased when the work was done in the mine at high temperature and high humidity, but did not increase outside in the environment of high temperature and low humidity.
2. In the mine, frequency of pulse increased remarkably at the time of the work and even at rest. But outside the mine, increasing tendency was not so clear.
3. The body temperature measured under the tongue and at the axilla increased markedly in the mine both at work (max. 39.4°C) and rest, but the increase outside was not so considerable.
4. The difference of temperature under the tongue and at the axilla was scarcely recognized in the mine, but outside the difference was considerable.
5. R. M. R. was calculating as 4.2 outside the mine, but 8.4 in the mine, suggesting that R. M. R. changes if the homeostasis does not exist because of the high thermal environmental conditions.