From ancient Roman baths to modern infrared saunas, passive heat therapy has become an increasingly popular therapeutic tool for improving health and reducing the risk and/or severity of disease. As the heat seeps in, your core temperature rises. The result? Your cardiovascular system kicks into gear, your blood vessels expand, your heart rate elevates – like a brisk jog without leaving the bench.
Call it a spa day with benefits; it’s this thermal tug-of-war that prompts powerful physiological responses.
But not all heat is created equal. In a new study from the University of Oregon, scientists turned up the temperature to see which type of passive heat therapy packs the most health punch: hot baths, traditional saunas, or those fancy far-infrared saunas.
The winner? Hot water immersion.
Among young, healthy adults, soaking in hot water triggered the strongest responses across the board, helping the body regulate temperature, boost circulation, and even enhance the immune system more effectively than either sauna style.
A group of 20 fit, health-conscious young adults (ages 20 to 28, non-smokers, and without medication) signed up for the study.
Guided by human physiology expert Christopher Minson, the researchers tracked a range of body signals – core temperature, blood pressure, heart rate, the heart's workload, and even the immune system’s activity.
Each person visited the lab 10 times; taking turns soaking in a hot tub (45 min at 40.5 °C/105 °F), sweating it out in a traditional sauna (3 × 10 min at 80 °C/176 °F), and basking in the warmth of a far-infrared sauna (45 min at 45–65 °C/113–149 °F). The team collected data before, during, and after each heat session to see what gets the body fired up – literally.
Among all methods, the change in temperature from baseline was greater in hot water immersion. Increased body temperature means increased blood flow and a greater inflammatory response. The team was not surprised by the study results.
"Hot water immersion gives you the most robust changes in core temperature because you can’t effectively dissipate heat as you can if you have contact with the air and you’re sweating to cool the body," explained lead author Jessica Atencio. "When you’re submerged in water, the sweat mechanisms aren’t efficient."
Minson does note regular physical activity can offer similar or in fact better results than heat therapies. But, for those who are unable to exercise, heat therapy can be a great alternative.
The study is published in in the American Journal of Physiology.
Source: University of Oregon via Science Daily
