By Richard Beever
OBJECTIVE To review the literature about the health benefits of far-infrared sauna (FIRS) use.
QUALITY OF EVIDENCE A search of Web of Science, EBSCO, Ovid MEDLINE, Ovid HealthSTAR, and EMBASE using the terms far-infrared and sauna, refined by limiting the search to studies of humans published in English, yielded 9 relevant papers (level I or level II evidence).
MAIN MESSAGE Far-infrared saunas are approved by the Canadian Standards Association and are sold to the public. The manufacturers claim numerous health benefits; however, the published evidence to substantiate these claims is limited. Four papers support the use of FIRS therapy for those with congestive heart failure and 5 papers support its use for those with coronary risk factors.
CONCLUSION There is limited moderate evidence supporting FIRS efficacy in normalizing blood pressure and treating congestive heart failure; fair evidence, from a single study, supporting FIRS therapy in chronic pain; weak evidence, from a single study, supporting FIRS therapy in chronic fatigue syndrome; weak evidence, from a single study, supporting FIRS therapy for obesity; and consistent fair evidence to refute claims regarding the role of FIRSs in cholesterol reduction.
Far-infrared saunas (FIRSs) are approved by the Canadian Standards Association and are sold to the public as recreational saunas. Manufacturers advertise numerous therapeutic effects, including weight loss, improved cardiovascular health, normalized blood pressure (BP), lowered cholesterol, and reduced pain, stress, and fatigue.1 These saunas are also being advertised in publications targeting Canadian physicians.1 The current North American market for FIRSs is valuated at approximately $60 million to $75 million and is growing rapidly, according to Aaron Zack, President and Chief Executive Officer of Sunlight Saunas (written communication, May 2009).
Traditional saunas use either wood stoves or 220-V heaters to heat the air to approximately 85°C, which then heats the occupant, mainly via convection. Some people find this heat uncomfortable. In contrast, FIRSs heat to approximately 60°C, providing a more comfortable and relaxing experience. They utilize 120-V infrared elements, similar to the infrared warmers on neonatal resuscitation beds, to radiate heat with a wavelength of around 10 μm (Figure 12). As infrared heat penetrates more deeply than warmed air, users develop a more vigorous sweat at a lower temperature than they would in traditional saunas. The cardiovascular demand imparted by thermoregulatory homeostasis (sweating, vasodilation, decreased afterload, increased heart rate, increased cardiac output) is similar to that achieved by walking at a moderate pace. As such, FIRS might be of particular benefit to those who are sedentary due to various medical conditions, such as osteoarthritis or cardiovascular or respiratory problems.
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