Effect of micro mist sauna bathing on thermoregulatory and circulatory functions and thermal sensation in humans

To examine the effects of micro mist sauna bathing, produced by water crushing method, we exposed ten male subjects to five cases of micro mist sauna, namely (1) room temperature (RT) 38 °C with 100 % (actually 91 %) relative humidity (RH), (2) RT 41.5 °C with 80 % (actually 81 %) RH, (3) RT 41.5 °C with 100 % (actually 96 %) RH, (4) RT 45.0 °C with 64 % (actually 61 %) RH, and (5) RT 45.0 °C with 100 % (actually 86 %) RH, and measured tympanic temperature, mean skin temperature, heart rate (HR), and cheek moisture content, as well as ratings of thermal and sweating sensation tympanic temperatures at RT 45 °C were significantly higher at 86 % RH than those at 61 % RH; however, those at RT 45 °C with 61 % RH were higher than those with 86 % RH during recovery. There were no significant differences at RT 41.5 °C between with 81 % RH and with 96 % RH. Mean skin temperature was the highest at RT 45 °C 86 % RH case, followed by at RT 41.5 °C 96 % RH, RT 45 °C 61 % RH, RT 41.5 °C 81 % RH, and finally at RT 38 °C 91 % RH. HR change showed the same order as for mean skin temperature. A significant difference in cheek moisture content was observed between RT 41.5 °C with 81 % RH and RT 45 °C with 86 % RH 10 min after the micro mist bathing. There were no significant differences between ratings of thermal sensation at RT 41.5 °C with 81 % RH and at RT 45 °C with 61 % RH and RT 45 °C with 61 % RH and RT 45 °C with 86 % RH. Between RT 45 °C with 86 % RH and RT 41.5 °C with 81 % RH, there was a tendency for interaction (0.05