Not All Heat Is Equal: Sauna and Hot Tub Affect the Human Body in Different Ways

Key Points:

• A University of Oregon study directly compared the physiological effects of hot water immersion, traditional sauna, and far-infrared sauna on healthy young adults, measuring core temperature, cardiovascular responses, and immune markers.
• Hot water immersion caused a greater rise in core body temperature and stronger cardiovascular responses, such as increased heart rate and cardiac output, compared to both types of saunas due to reduced heat dissipation through sweat evaporation.
• Only hot water immersion triggered a measurable increase in inflammatory cytokines and specific immune cells, indicating a temporary mild inflammatory state similar to that induced by exercise.
• The findings suggest hot water immersion provides the most robust heat stress stimulus, which may have implications for passive heat therapy as a complementary approach for improving cardiovascular health, especially in individuals unable to exercise.
• The study focused on short-term effects in healthy adults and cautions that prolonged heat exposure can be risky for people with heart or blood pressure conditions, emphasizing the need for medical clearance before regular heat therapy.