Effects of bathroom temperature on thermal responses during whole-body bathing, half-body bathing and showering

This study examined the effect of bathroom thermal conditions on physiological and subjective responses before, during and after three kinds of bathing. Bathing methods were as follows: whole-body bath (W-bath), half-body bath (H-bath) and showering. The air temperature of the dressing room and bathroom was kept at 10, 17.5 and 25°C. Eight healthy males bathed for 10 min under nine conditions on separate days. Water temperature of the bathtub and shower was kept at 40 or 41°C, respectively. Rectal temperature (T_re), skin temperature (T_sk), blood pressure (BP), heart rate (HR), body weight loss and blood characteristics (hematcrit: Hct) were measured. Thermal sensation (TS) and thermal comfort (TC) were also recorded. During bathing, BP decreased rapidly during W-bath and H-bath, and HR during a W-bath was significantly higher than during a H-bath or showering. The double products (systolic blood pressure × heart rate) due to W-bath during bathing were also greater than for a H-bath and showering. There was no distinct difference in Ht among the nine conditions. However, significant differences in body weight loss were observed among the bathing methods: W-bath > H-bath > showering. The changes in T_re after a H-bath at 25°C were similar to those of W-bath at 17.5 and 10°C. The large differences in T_re were due to the room temperature for the H-bath. TS and TC after bathing significantly differed with the three kinds bathing at 17.5 and 10°C. Especially with showering, TS and TC were significantly cooler and more uncomfortable than W-bath and H-bath. These results suggest that the physiological strains of a H-bath and showering were less than a W-bath. However, it is particularly important with a H-bath and showering to maintain an acceptable temperature in the dressing room and bathroom, in order to bathe comfortably and keep the body warm.