Hot Baths May Offer Greater Health Benefits Than Saunas, Research Suggests
Soaking in a hot bath ("hot water immersion") and using a sauna are both popular ways to ease muscle aches and feel warm. However, new research indicates that taking a hot bath might provide greater physiological health benefits than sitting in a sauna.
This conclusion comes from a study conducted by the Bowerman Sports Science Center at the University of Oregon. The research directly compared the physiological effects of immersing oneself in a hot tub versus sitting in either a traditional dry heat sauna or a modern far-infrared sauna. The findings were recently published in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.
The study demonstrates that soaking in hot water works by significantly elevating core body temperature. This core heating triggers beneficial responses, including lowered blood pressure, stimulation of the immune system, and, over time, improved adaptation to heat stress. Importantly, these effects persist for some time after the "heat therapy" session ends.
"We compared the passive heating modalities most commonly used in daily life and explored in scientific research," explained Jessica Atencio, the study's lead author and a PhD student at the University of Oregon. The research focused on isolating the physiological responses of each heating method in a young, healthy population (20 participants, aged 20-28, who exercised regularly).
Under the guidance of Professor Christopher Minson, Director of the Bowerman Sports Science Center, researchers monitored participants before and after each session. Measurements included:
Core body temperature
Blood pressure
Heart rate
Cardiac output (the volume of blood pumped by the heart per minute)
Immune cell counts
Blood biomarkers for inflammation
Key Findings:
Superior Core Heating: "We found that hot water immersion was the most effective method at increasing core body temperature," stated Atencio. "Elevating core temperature is the primary stimulus driving the subsequent physiological responses." This increase promotes greater blood flow, benefiting vascular health.
Unique Inflammatory Response: Blood samples taken after each session revealed a crucial difference: only hot water immersion produced a detectable inflammatory response, measured by changes in inflammatory cytokine levels and immune cell counts.
Mechanism Explained: Atencio noted the reason for the superior heating: "Hot water immersion causes the most dramatic change in core temperature because when you're immersed in water, you can't dissipate heat as effectively as you can in air. The efficiency of sweating – your main cooling mechanism – is greatly reduced in water."
Implications for Health:
"If people are willing to do a little heat therapy, doing it in moderation can help improve health," said Professor Minson. "That's something that's been shown in our lab and in many other studies."
Minson added that while regular exercise provides benefits similar to, and often exceeding, those of heat therapy, passive heating like baths or saunas presents an attractive alternative for individuals who are unable or unwilling to exercise. "It's a very peaceful experience. We want people to do it wisely and safely," he concluded.