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Far-infrared sauna exposure at 65°C elevates core temperature
Elliott J Jenkins1, Joseph A Killick1, Sally R Grimm1
1Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK.
Experimental Physiology
|July 31, 2026
Summary
Far-infrared (FIR) saunas at 65°C significantly raise core body temperature and cause physiological heat strain. This study confirms FIR saunas effectively increase body heat when used at higher temperatures.
Area of Science:
- Physiology
- Environmental Health
- Thermoregulation
Background:
- Far-infrared (FIR) saunas are popular wellness tools, but their ability to elevate core body temperature is not well understood.
- Previous studies at lower temperatures (around 45°C) showed limited heat storage, raising questions about FIR sauna efficacy.
Purpose of the Study:
- To investigate if FIR sauna exposure at a higher temperature (65°C) increases core body temperature.
- To assess the thermoregulatory, cardiovascular, and perceptual responses to FIR sauna bathing at 65°C.
Main Methods:
- Twelve healthy adults (6 female) underwent a single 45-minute FIR sauna session at 65°C.
- Measurements included rectal temperature, skin temperature, heart rate, blood pressure, plasma volume, and subjective perceptions of heat and discomfort.
Main Results:
- Rectal temperature increased by 1.4°C, with significant elevations observed from 20 minutes.
- Heart rate doubled, plasma volume decreased by 11.6%, and participants reported extreme heat and discomfort.
- Skin temperature rose rapidly, and mean arterial pressure decreased post-exposure.
Conclusions:
- FIR sauna use at 65°C induces significant increases in core body temperature and systemic physiological strain.
- The study supports the potential of FIR saunas as a heat-based intervention when applied at sufficiently high temperatures.
- Effectiveness in raising core temperature is dependent on the thermal load imposed by the sauna environment.
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