A recent study suggests we can all quit the gym and get in the spa instead. Say goodbye to treadmills; no need to buy that expensive new Peloton; just get in your hot tub for an hour.
Really?
Well…not exactly, but close.
In an article appearing in the Journal of Applied Physiology, entitled “The health benefits of passive heating and aerobic exercise: To what extent do the mechanisms overlap?”, researchers from Coventry University make the case that soaking in a hot tub or sitting in a sauna can provide some of the same fitness advantages as actual exercise.
From the abstract: “Several recent studies have shown that passive heating induces numerous health benefits, many of which are comparable with exercise, such as improvements to cardiorespiratory fitness, vascular health, glycemic control, and chronic low-grade inflammation.”
According to the authors, globally, about 25% of adults don’t meet the minimum recommended physical activity levels of 150 minutes of moderate intensity activity or 75 minutes of vigorous intensity activity per week, or a combination of both.
Meanwhile, although the health benefits of heat therapy have been extolled though out human history, until recently those benefits were largely viewed as unscientific.
For example, the ancient Greeks and Romans were famous for their love of hot baths. The Greek physician, Hippocrates, is known to have celebrated the therapeutic properties of heated water. Other Greek philosophers including Plato wrote of the benefits of hydrotherapy.
In Japan, hydrotherapy has also long been a part of the culture – indeed they have revered hot water’s healing power for centuries.
The Japanese have a saying, Mizuno- Kokoro, which translates to “mind like water,” referring to a state of peace and harmony.
Dry saunas are a popular pastime in many Nordic countries, and have been since sometime around 2,000 BC. Once fueled by wood burning fires and now with electrical heating elements, these are usually heated to 70-110°C with a humidity between 5-20%. Today, in Finland alone, a country of 5.5 million people, there are about 3 million saunas.
Similarly, in the Native American traditions, sweat lodges have long been used to purify the body and mind, and to uplift the spirit. Believed to be an ancient and pure medicine, hot rocks are placed in a center pit and medicinal herbs are added. Water is poured on the rocks which produce a steam that is believed to purify and heal.
The symbolism of the steam and the structure of the sweat lodge is meant to represent the womb, life’s starting place.
These cultures and many others have all noted the health benefits of heat therapy, but until recently, evidence was anecdotal.
In their recent review, the Coventry University authors cite a variety of studies that have looked into the healing powers of heat therapy.
For example, in a 2015 long-term study of middle-aged Finnish men, it was found that sauna bathing frequency was associated with a decreased risk of fatal cardiovascular disease.
Those who participated in four to seven sauna sessions per week had an 50% reduction in the risk of fatal cardiovascular disease when compared to those who went once a week.
Moreover, researchers from Japan have shown that higher frequencies of habitual hot tub bathing are also beneficial against fatal and non-fatal cardiovascular events.
Photo credit: Master Spas 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.
