I have a client who recently brought me a brochure from a spa which reads:
"The Sauna soothes and relaxes tired muscles, helps maintain clear healthy skin, provides a cardiovascular workout, burns as many as 300 calories in a session, increases metabolic rate, improves circulation and provides an after glow of a rosy complexion."
Thank goodness my client is educated enough to know that this claim regarding "cardiovascular workout etc." is hogwash. She asked the director of the club to submit "proof" of this claim after which she was handed something from the manufacturer Finlandia. She asked me to bring her evidence that disputes this claim, which of course, I am happy to do but don't exactly know how to debunk this obvious myth. Can you help?
Oh, it's not hogwash nor a debunkable myth. The truth is that there is actually a cardiovascular training effect from saunas.
JAMA, the Journal of the American Medical Association (8/7/81), reported that "Regular use of a sauna may impact a similar stress on the cardiovascular system, and its regular use may be as effective, as a means of cardiovascular conditioning and burning of calories, as regular exercise."
The study also states, "A moderately conditioned person can easily sweat off 500 grams in a sauna, consuming nearly 300 kcal, which is equivalent to running 2-3 miles."
A similar study in the Journal of the American College of Cardiology (J Am Coll Cardiol. 2002 Mar 6;39(5):754-9) concluded: "Repeated sauna treatment improves vascular endothelial function, resulting in an improvement in cardiac function and clinical symptoms."
Even NASA has looked at infrared stimulation (similar in principle to saunas) as an effective way to maintain cardiovascular conditioning during long space flights.
PTontheNET.com author Gray Cook recommends the sauna in his outstanding book, "Athletic Body in Balance" saying that:
"Dry heat causes all of the blood vessels close to the surface of the skin to dilate, moving heat away from the center of your body to the surface of your body. That heat then leaves the body through evaporation into the dry atmosphere of the sauna. To move this blood and produce sweating, your heart has to work as hard as it would in response to low level exercise. Your heart rate will often get as high in a sauna as it does when you are leisurely riding a stationary bike."
Your body responds to the sauna by increasing your heart rate, cardiac output (as much as double your resting output) and metabolic rate - just like it responds to traditional CV exercises. This beneficial stress does indeed lead to a cardiovascular training effect.