The effects of two types of clothing on seasonal heat tolerance.

The aim of this study was to look at changes in seasonal heat tolerance due to acclimatization produced by different types of clothing. A group of 12 female adults served as subjects in the study which lasted for 3 months from April to June during which the ambient temperature gradually rose. Of the group 6 of them (skirt group) wore knee-length skirts daily, and the others (trouser group) were dressed in full trousers during this acclimatization period. The heat tolerance before and after the acclimatization period was compared between the two groups under conditions in which relative humidity was 30% and ambient temperature was raised to 37 degrees C. Rectal temperature, mean skin temperature and the loss of body mass caused by sweating were measured in the two groups. Before the acclimatization period, no significant differences were found between the two groups. However, observations after the acclimatization period showed higher rectal temperatures in control conditions (ambient air temperature 28 degrees C, relative humidity 60%) in the skirt group. A lower increment of rectal temperature during heat exposure (ambient air temperature 37 degrees C, relative humidity 30%) was also found in this group. Finally, the subjects in the skirt group lost less body mass due to sweating during heat exposure. Consequently, the overall index of physiological strain in the skirt group tended to show a lower value after the period of warm acclimatization. It was concluded that the subjects wearing knee-length skirts improved their heat tolerance with the advance of the seasons.