Changes in selected physiological indicators and thermal stress assessment under the influence of baths in a dry and wet sauna in young healthy women

Abstract

Background There are differences between dry and wet sauna baths because of the heat load and human body’s reactions. High humidity in a wet sauna makes evaporation of sweat from the skin surface more difficult. In addition, the dynamics of sweating is different in men and women. The aim of the study was to assess changes in physiological indicators and to compare the impact of dry and wet saunas on the thermal comfort feeling, which was assessed using the Bedford thermal scale, and the physiological strain index (PSI) and the cumulative heat stress index (CHSI) in young healthy women. Material and Methods Ten women aged 22−24 years took part in the study. A session in each sauna lasted 60 min and consisted of 3 thermal 15-min exposures, in 5-min intervals for rest and cooling with water. The temperature in the dry sauna was 91±1.2°C and in the wet sauna 59±1.3°C, while the humidity was 18±0.7% and 60.5±0.8%, respectively. Body weight, systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), rectal temperature (T re ) and the thermal sensation (Bedford scale) were also measured. The PSI and CHSI values were both calculated. Results The average weight loss after a dry sauna bath was significantly higher than after a wet sauna bath. Significantly higher increases in T re , as well as in HR were observed after treatment in the wet sauna, compared to the dry sauna. Both treatments resulted in an increase in SBP and a decrease in DBP. The arduousness of thermal discomfort and the levels of PSI and CHSI were skurgreater in the wet sauna bathing than in the dry sauna. Conclusions Heat exposure in the wet sauna creates a greater burden for young women’s bodies than the same dry sauna treatment, and the changes observed in the examined traits were higher than in men subjected to similar thermal loads. Med Pr. 2019;70(6):701–10

Keywords

• body temperature
• dry sauna
• wet sauna
• heat stress
• temperature sense
• physiological strain