One of the earliest studies of heat therapy showed that both sauna and hot water bathing, once or twice per day, five times per week, over four weeks, enhanced the function and wall structure of the heart in patients with chronic heart failure.

It was also found that four weeks of sauna use improved blood pressure, exercise tolerance, fitness levels and reduced hospital admissions.

And research into daily hot tub therapy for three weeks was shown to lower blood glucose levels in patients with type 2 diabetes.

These findings all indicate that heat therapy can benefit both diseased and healthy populations in a variety of different ways.

According to the review’s authors, it is thought that repeated elevation in core body temperature increases blood flow to the skin, which has the following effects: “The elevation in blood flow results in an increase in the frictional force between the blood and the inside of your blood vessel walls. This triggers the release of molecules into the bloodstream. When this response is repeated over months, these molecules assist in the formation of new blood vessels and repair damaged ones. This can help lower blood pressure as well as increase oxygen and glucose delivery to the muscle, which collectively can reduce cardiovascular disease risk and improve fitness.”

At the end of the day, the authors find that both exercise and heat therapy can promote cardiovascular health by comparable amounts in improvements in fitness.

But before you cancel your gym membership and invest the savings in a hot tub, it’s important to note that regular hot water bathing isn’t a substitute for all of the benefits of exercise, such as fat loss and building muscle mass.

However, for the committed couch potato or the exercise adverse, soaking in the hot tub is scientifically better than nothing.