Soaking in hot water has many surprising and long-lasting health benefits

After a long day or an intense workout, few things are more inviting than the warmth of a hot tub or the dry embrace of a sauna. But beyond relaxation, which heat therapy actually benefits your body the most?

According to a new study from the University of Oregon’s Bowerman Sports Science Center, hot tubs may do more than just soothe sore muscles – they might deliver the most powerful boost to your overall health.

Hot tubs vs. saunas

The study explored the physiological effects of three common types of passive heating: hot tubs, traditional dry saunas, and modern far-infrared saunas.

Researchers set out to see how these different approaches affect core body temperature, cardiovascular health, and immune responses.

Jessica Atencio is a lead author of the study and a doctoral student in the Department of Human Physiology at the University of Oregon.

“We compared the most commonly utilized modalities of passive heating as they’re used in everyday life and studied in scientific research,” she said. “No studies have compared the acute responses between the three.”

How the body reacts

To get answers, Atencio and her team recruited ten men and ten women between the ages of 20 and 28. All participants were regular exercisers and generally healthy.

This narrow focus allowed the researchers to isolate how young, active bodies respond to each type of heat exposure.

Over the course of the study, the team monitored a range of physiological indicators. These included heart rate, blood pressure, cardiac output (how much blood the heart pumps per minute), and levels of inflammatory biomarkers. Blood samples were taken before, during, and after each session to track changes.

What they found was striking: hot-water immersion raised core body temperature more significantly than either sauna type. With that rise came a host of benefits.

“We saw that hot water immersion was the most impactful in increasing core body temperature, which is the main stimulus for these subsequent responses,” Atencio said.

“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.”

Heat you can’t sweat away

Part of what makes hot water so effective is that it limits the body’s ability to cool itself down. In a sauna, for example, you sweat and that sweat evaporates, carrying heat away from your body.

But in a hot tub, sweat doesn’t evaporate – it just mixes with the surrounding water. This inefficiency in heat loss means your body stays hotter longer, triggering more physiological change.

“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,” Atencio said. “When you’re submerged in water, the sweat mechanisms aren’t efficient.”

Only hot water immersion led to measurable changes in immune function. These included spikes in inflammatory cytokines – small proteins that play a key role in cell signaling. They also triggered boosts in immune cell activity.

Hot tubs benefit health

For study lead author Professor Christopher Minson, who has studied heat therapy for over twenty years, the implications are both exciting and practical.

“There’s no doubt 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,” he said.

“If you repeat these stresses over time, our lab and many others have shown that they are consistent with improved health.”

While he emphasizes that regular exercise still offers broader health benefits, he also sees heat therapy as a useful alternative. This is especially true for people who can’t, or won’t, commit to exercise.

“It can be a very peaceful, sometimes religious, sometimes cultural and sometimes social experience,” Minson added. “And I think those aspects contribute to the health benefits and are critically important.”

Know your limits – and options

That said, both Minson and Atencio stress the importance of safety. “We want people to be smart and safe about it,” Minson said.

“We need to make sure that they are cleared by their physicians 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, knows people who combine workouts with post-exercise heat therapy. But even if you’re not training for a marathon, she sees value in incorporating passive heating into your wellness routine.

“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.”

So the next time you’re choosing between a soak or a sit in dry heat, science suggests the hot tub may give you more than relaxation – it might offer a better shot at long-term health.

The study is published in the American Journal of Physiology.

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