The case for including the hot tub in your heat-therapy regimen.
There might be more to gain from hot tubs than whole-body relaxation and stress relief. New research out of the University of Oregon found that submerging in hot water may have health benefits comparable to, if not greater than, popular therapies like saunas.
In the study, researchers compared the effects of three popular methods of heat therapy: soaking in a hot tub, sitting in a traditional dry heat sauna, or sitting in a far-infrared sauna. They collected data (body temperature, blood pressure, heart rate, immune cell populations, inflammation biomarkers, and more) from 20 young, healthy participants before, during, and after their heat exposure.
The results? Soaking in a hot tub most significantly elevated core body temperature, which leads to an increase in blood flow that the researchers say is beneficial for vascular health. What's more, the hot tub therapy was the only method studied that stimulated an immune system response; concentrations of immune cell populations increased up to 48 hours after the treatment.
The effect on core temperature has to do with your body’s primary cooling mechanism: sweating. As your temperature elevates, your body produces sweat to cool you down via evaporation. But that evaporation can’t occur when you’re floating in a vat of water, surrounded by humid air. Cue a greater rise in body temperature.
James Gu, Equinox’s senior director of spa, says to think of it this way: If you were to place your hand in an oven that’s 212°F, you might be able to hold it there for a few minutes before it gets uncomfortable. But if you were to stick your hand into water of the same temperature (read: boiling), it’s going to cause some damage, he explains. “It comes down to thermal dynamics,” he adds. “The reason why a cold plunge is so much more effective than standing in cold air is because you have thermal transfer at a much higher rate in moisture; the thermal potential of water is much higher than that of air.”
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Though the study group was small, to Gu, this research is exciting, as it builds upon the many studies showcasing potential health benefits of heat therapy. For instance, a 2022 study from the University of Eastern Finland found that frequent sauna baths may offset the increased risk of all-cause mortality related to high levels of hsCRP (high-sensitivity C-reactive protein). Elevated CRP may be a marker of hidden chronic inflammatory conditions, according to the researchers. Another 15-year follow-up study from the University showed that people who took a sauna four to seven times a week were 61 percent less likely to experience a stroke than those who took a sauna once a week. This was attributed to potential mechanisms like a reduction in blood pressure, improved cardiovascular function, and a positive impact on the autonomic nervous system, among others.
“There has been [some] research done on hot tubs or steam rooms, but kind of conceptually and theoretically, it makes sense that those should not only be as good, but potentially better [than saunas], because of the moist heat,” says Gu.
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To reap safely the hot tub’s potential perks, cap your hot tub session at 20 minutes with a water temperature no higher than 104°F. Look out for signs of heat-related illness, including dizziness, racing heart, nausea, weakness, tiredness, headache, and confusion, among other symptoms.
Thanks to its associations with spas and vacations, plus the feelings of relaxation it tends to bring about, the hot tub may feel like an easy first step into heat therapy. But why stick with just one? Once you’re acclimated, add some variety to your routine and rotate between a steam, a sauna, and a soak — all available at your Equinox Club.