The Science of Sauna
Sauna use associated with reduced risk of cardiac and all-cause mortality.
Taking a sauna for the purposes of purification, cleansing, and healing is an ancient human practice dating back thousands of years across many cultures around the world. Societies have long used sauna because they noticed that it relaxed the mind and body, reduced pain and improved flexibility and sleep.
But how does sauna work and what does modern science tell us about this ancient practice that continues to be so popular today?
Metabolic and physiological responses to heat stress:
1. The heat from sauna increases heart rate and causes blood vessels to relax and dilate. Skin and then core body temperature increase. Under these conditions, cardiac output (measure of the amount of work the heart performs in response to the body's need for oxygen) increases by 60-70%, while the heart rate increases and the stroke volume (amount of blood pumped with each beat) remains unchanged. In sum, the amount of blood being circulated around the body per minute is dramatically increased. This increased blood circulation will deliver more valuable oxygen and micronutrients to every organ of the body, enhancing their function and performance!
2. Sauna not only relaxes smooth muscle in the vascular system but also in the airways or bronchial tubes. This can benefit chronic conditions such as chronic bronchitis, asthma and COPD.
3. Repeated sauna use acclimates the body to heat and optimizes the body's response to future exposures. This is likely due to a biological phenomenon known as hormesis, a compensatory defense response following exposure to a mild stress that is disproportionate to the magnitude of the stressor itself. Hormesis triggers a vast array of protective mechanisms that not only repair cell damage but also provide protection from subsequent exposures to more devastating stress.
4. Passive exposure to extreme heat induces a thermoregulatory response involving neurologic, hormonal, cardiovascular, and cytoprotective mechanisms that work together to decrease inflammation and restore equilibrium to body and mind.
5. The physiological gains associated with sauna use are remarkably like those derived from exercise. In fact, sauna use has been proposed as an alternative to exercise for people who are unable to engage in physical activity because of chronic disease, physical limitations, or injury.
Do you notice a common theme? With sauna, we see again the positive metabolic, physiological and biochemical effects on our body and mind just like with movement, exercise and cold showers.
Interesting outcomes data in sauna research:
The effects of sauna are not just skin deep. Sauna research emerging today from around the world suggests that sauna could be used to increase lifespan and improve overall health, based on compelling data from observational, interventional, and mechanistic studies. There is compelling evidence that sauna is linked to decreased prevalence of high blood pressure, improved measures in congestive heart failure, decreased cardiovascular disease and improved mental and cognitive health. For example:
--An ongoing prospective population-based cohort studies of health outcomes in more than 2,300 middle-aged men from eastern Finland, has identified strong links between sauna use and reduced incidence of death and disease.
--Other studies show findings that men who used the sauna two to three times per week were less likely to die from cardiovascular-related causes compared to non users. In addition, frequent sauna users were found to be 40 percent less likely to die from all causes of premature death. These findings held true even when considering age, activity levels, and lifestyle factors that might have influenced the men's health.
--One study revealed that frequent sauna use reduced the risk of developing dementia and Alzheimer's disease.
--Men participating in the KIHD study who used sauna 4-7 times per week were 77% less likely to develop psychotic disorders, regardless of their dietary habits, socioeconomic status, physical activity, and inflammatory status (as measured by C-reactive protein).
--Additional interesting points were that sauna duration and temperature play a role in outcomes as might be expected. One study found a dose-dependent reduction in cardiovascular-related mortality, all-cause mortality, and Alzheimer's disease.
--Studies conducted in Finland have shown that people using sauna 2-3 times per week, are 27% less likely to die from cardiovascular-related causes, and frequent users (4-7 times per week) are 50% less likely to die from cardiovascular-related causes. In addition, the frequent sauna users were found to be less likely to die from all causes of premature death, regardless of age, activity levels.
--Findings from a prospective, multi-centered, randomized controlled trial involving 149 patients with advanced congestive heart failure demonstrated that 4 weeks of sauna therapy improved the patients' endurance, heart size, and disease status compared to those who received standard medical care.
--Men who used sauna 2-3 sessions every week were found to had a 24% lower risk of developing hypertension and men who used the sauna 4-7 times per week had a 46% lower risk of hypertension compared to men who used sauna only once per week. Even a single sauna session has been shown to lower blood pressure and improve arterial compliance.
--In a study involving 19 healthy adults, the effects of a single 25-minute sauna session were comparable to moderate physical exercise with respect to cardiovascular measures. During sauna use or moderate exercise, the participants' heart rate and blood pressure increased immediately, but after the sauna or exercise session, participants' blood pressure and heart rate began to drop below baseline levels. Like exercise, long-term sauna use generally improves overall blood pressure, endothelial function, left ventricular function, and reduces inflammation.
--Contraindications to sauna bathing include unstable angina pectoris, recent heart attack and significant valvular heart disease. Alcohol consumption during sauna bathing increases the risk of low blood pressure, arrhythmia and should be avoided.
If this is not enough to want you to take a sauna...Grab a towel and enjoy!