The influence of extreme thermal stress on the physiological and psychological characteristics of young women who sporadically use the sauna: practical implications for the safe use of the sauna.
Level 3 - non-randomized controlled study
Non-randomized within-subject comparative experimental trial.
PubMed 38344040 · doi:10.3389/fpubh.2023.1303804
What was done
Twenty-two full-time female university students who sporadically used saunas underwent two 20-minute sauna sessions at 80°C and 120°C. Baseline physical activity (Polish short IPAQ) and body composition (InBody270) were evaluated. Physiological parameters, including heart rate, energy expenditure, and blood pressure (SBP and DBP), were measured indirectly via Polar V800 heart rate monitors and Omron M6 Comfort blood pressure monitors. Mood was assessed using the Profile of Mood States (POMS) questionnaire. Predictors of heat exhaustion, heat stress, and syncope during the 120°C session were analyzed using classification and regression trees (CRT) with cross-validation.
What was found
No baseline or post-exposure absolute numbers were reported in the abstract. Both 80°C and 120°C sessions led to statistically significant (p < 0.001) decreases in DBP and body mass, as well as significant increases in heart rate and forehead temperature. SBP decreased significantly at 80°C (p < 0.001) but not at 120°C. Sauna bathing at 80°C significantly (p < 0.001) increased vigor while decreasing tension, depression, anger, fatigue, and confusion; bathing at 120°C produced the opposite psychological effect. Syncope occurred in some participants during the 120°C session, with vomiting and confusion identified as the primary predictors.
Why it matters
While 80°C sauna bathing improves mood and hemodynamics in sporadic female users, extreme heat exposure at 120°C causes acute heat stress, syncope, and mood deterioration, indicating that 120°C is unsafe for this demographic.
Limits
The abstract reports no exact physiological or psychological numerical values, only directional p-values. The sample size is very small (n = 22) and restricted to young, healthy female university students who use saunas sporadically. The abstract does not specify whether the order of temperature exposure was randomized.
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