Don’t Like Exercise? Try a Hot Tub Soak

Study finds similar post-recovery cardiovascular responses in cycling and heat therapy

Rockville, Md. (March 16, 2021)—Research suggests that soaking in a hot tub for 60 minutes may provide similar post-activity cardiovascular benefits as 60 minutes of cycling. This news could help people who are not able to exercise due to their health. The study is published ahead of print in the Journal of Applied Physiology.

“There are cardiovascular disease patient populations that would stand to gain tremendously from exercise, yet cannot do so. Heat therapy may be a viable alternative to exercise for these patient populations.”

Exercise improves cardiorespiratory and blood vessel health by lowering blood pressure and reducing the amount of work the heart needs to do to pump blood throughout the body. Previous research has shown that heat immersion, such as in a hot tub, also improves these factors, but less is known about how long after exertion the benefits last. Understanding the beneficial effects of heat therapy is important because many people do not meet recommended physical activity guidelines or cannot exercise due to underlying health conditions or mobility issues.

In a new study from the University of Oregon, a small group of healthy, young adults participated in two trial conditions on two separate days. One condition consisted of cycling at 60% maximum effort for an hour. In the other condition, the volunteers sat almost up to their shoulders in a hot tub with 105-degree F water until they felt very hot, then were submerged to just above their waist for a total of an hour. During both trial conditions, the volunteers drank 16.9 ounces of water to replace fluid loss from sweat. The researchers measured the participants’ heart rate, core body temperature and blood pressure throughout the trial. After each activity was complete, the research team took ultrasound images of blood flow in the participants’ thigh and upper arm arteries and continued to take vital signs.

The researchers found increased heart rate and dilation of the arteries, and lower blood pressure during both the cycling exercise and heat conditions. "We know that the post-exercise period is an important timeframe that links exercise with long-term cardiovascular benefits. That similar post-stress cardiovascular responses were observed following exercise as following hot water immersion is compelling," said Christopher Minson, PhD, corresponding author of the study. “This is important because there are cardiovascular disease patient populations that would stand to gain tremendously from exercise, yet cannot do so. Heat therapy may be a viable alternative to exercise for these patient populations,” the researchers wrote.

Read the full article, “Hemodynamics of post-exercise vs. post hot water immersion recovery,” published ahead of print in the Journal of Applied Physiology.

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