After a demanding workout, there’s little better than recovering with a nice dip in the hot tub, or sitting inside a sweat-inducing sauna. But which one stimulates the heart and boosts our immune system the most? Experts at the University of Oregon have the answer. In a recent study published in the American Physiological Society, researchers from the Bowerman Sports Science Center at the University of Oregon pitted the effects of relaxing in a hot tub against sitting in a traditional heat driven dry sauna, or spending time in a more modern far infrared sauna. “No studies have compared the acute responses between the three,” said the study’s lead author, Jessica Atencio.
How was the study carried out?
The benefits of raising the core body temperature include lowering our blood pressure and are thought to extend to stimulating a better immune response. To find out whether hot tubs, dry saunas, or infrared saunas worked best the scientists worked with a relatively small sample of 20 people (10 male and 10 female) between the ages of 20 and 28 years. Before the participants engaged in the three different recovery methods, measurements such as body temperature, blood pressure, heart beats per minute, immune cell and blood biomarkers were collected. This data was then measured again during each recovery method, and finally once the activity was completed.
Which Wins? Hot Tub, Dry Sauna, or Far Infrared Sauna?
The experts found that all three methods were beneficial to a certain degree. “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,” explained Atencio. But when it came to choosing a clear winner, one method went further than the rest. “We saw that hot water immersion was the most impactful in increasing core body temperature, which is the main stimulus for these subsequent responses,” she added.
The hot tub was the only method associated with measurably increased cytokine levels—the body’s response to inflammation. “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 Atencio of the hot tub. “When you’re submerged in water, the sweat mechanisms aren’t efficient.”
The study was overseen by Chris Minson, a professor in human physiology. “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,” he explained. “If you repeat these stresses over time, our lab and many others have shown that they are consistent with improved health.”
The report concluded that a single session of hot water immersion leads to the greatest physiological strain compared with both traditional and far infrared saunas. The significant increase in core temperature, bolstered by hot water immersion, resulted in “cardiovascular strain and immunological alterations, which may lead to beneficial health adaptations with repeated exposures.”
