A new University of Oregon study shows hot tubs raise core body temperature more than saunas, delivering greater cardiovascular and immune benefits
Hot tubs may be more than just a luxury. A new study from the University of Oregon’s Bowerman Sports Science Center found that soaking in hot water outperforms both traditional dry saunas and far-infrared saunas in raising core body temperature and triggering positive physiological effects.
Researchers say that temperature boost leads to greater increases in blood flow, improved vascular function and even an enhanced immune response, offering potential health benefits for those unable or unwilling to exercise.
“We compared the most commonly utilized modalities of passive heating as they’re used in everyday life and studied in scientific research,” said lead author Jessica Atencio, a doctoral student in the lab of Christopher Minson. “No studies have compared the acute responses between the three.”
The findings, published last month in the American Journal of Physiology, examined how 10 men and 10 women ages 20 to 28 (and all regular exercisers) responded to dry heat saunas, far-infrared saunas and hot tubs. Researchers monitored key health indicators including blood pressure, heart rate, cardiac output and biomarkers tied to inflammation and immune function before, during and after each session.
Hot-water immersion proved to be the most effective in raising core body temperature, the key factor driving downstream benefits.
“Increasing body temperature causes an increase in blood flow, and just the force of blood moving across your vessels is beneficial for your vascular health,” Atencio said.
Notably, only hot water immersion triggered a measurable inflammatory response.
“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,” she said. “When you’re submerged in water, the sweat mechanisms aren’t efficient.”
Christopher Minson, director of the Bowerman Sports Science Center and the Kenneth M. and Kenda H. Singer Endowed Professor of Human Physiology, believes the benefits of passive heating are both physical and psychological.
“There’s no doubt in my mind that if people are willing to do some heat therapy, it’s going to align with improved health, as long as it’s done in moderation,” Minson said. “If you repeat these stresses over time, our lab and many others have shown that they are consistent with improved health.”
Although exercise remains the gold standard, the findings offer a promising alternative for individuals who are unable or unwilling to work out. And as connection becomes a central theme in the fitness and wellness conversation, Minson noted that the social nature of heat therapy may offer added value. Whether it’s part of a cultural ritual or simply shared time in a hot tub, the communal aspect may amplify its health benefits.
Still, he emphasized the importance of safety and medical clearance before beginning any heat regimen.
“We want people to be smart and safe about it,” he said. “We need to make sure that they are cleared by their physicians or others for heat therapy or for exercise, whether it’s mild to moderate walking or jogging or strength training. Then they’ll be fine to do heat therapy.”
Atencio, a runner herself, added that many athletes already incorporate heat therapy into their routines and for others, it may be the next best thing.
“We always say that exercise is the primary nonpharmacological treatment that people should be doing to promote health, but some people can’t or just won’t exercise,” she said. “Heat therapy is good supplementation.”
For the fitness and wellness industry, the study reinforces the growing interest in hydrotherapy as more than a luxury or an add-on amenity at a gym, but a science-backed method.
