Abstract
It has been suggested that the immersion of subjects into a hot water bath (Bath Method) may be useful and simple method for testing human heat tolerance. It is probable that the bath method may fail to evaluate valid heat tolerance because of the forced uniformization of skin temperature. To confirm the validity of the bath method, sublingual temperature and skin temperature of forehead, chest, back, forearm, thigh and calf were examined when the two adult male subjects were exposed to various hot air environment in the nude for an hour in the sitting position. The following results were obtained.
1) On every skin temperature measured at six different regions, the difference of skin temperature between the two subjects observed under the very hot condition was smaller than that observed under the cooler condition.
2) The range of skin temperature (the difference between the highest and the lowest value among skin temperatures measured at six different regions) was rather small under very hot conditions.
3) Relatively large positive correlations were found among every skin temperature measured at six different regions. It was revealed by the principal component analysis that skin temperatures at various regions were controlled mostly by a single common factor.
The above findings indicate that the forced uniformization of skin temperature brought about by the bath method will not necessarily interfere with the valid evaluation of human heat tolerance.
