If we are to believe the advertising of saunas, they have many health benefits and hardly any disadvantages. But are all these allegations?

Most people probably use the sauna because of the relaxing and relaxing effect, because they like it here with their bodies involved, to be naked around, to enjoy the warmth in winter, because their skin clean and smooth after a sauna session …
If we are to believe the advertisements, it is not only fun and nice sauna but it also has many health benefits. However, those allegations prove to be inaccurate.
On the other hand quite a few misconceptions circulate about the possible dangers of sauna for heart patients, diabetics, children, pregnant women …
Two types of sauna

There are two types of sauna: the classical (Finnish) sauna and infrared sauna.
In the classical (Finnish) sauna, the air warmed by a heat source. The operation is based on the interaction between hot, dry air (temperatures between 50-100 ° C, relative humidity of 15 to 30% and cold water.
The operation of an infrared sauna is based on the infrared heat generated by electric heaters. The characteristic of infrared heat is that heat is transferred to the skin without the hot air in sight. An Infrared Sauna is sauna, but not really a (radiation) heat cabin. The double walls of the Infrared cabin temperature will also rise to 40 ° to 60 ° C.

see also article: Infrared Sauna: panacea or gadget?
1. What happens in the (traditional) saunas

The sauna has a number of physiological effects on the body.

Heart function
The human body has a built-in thermostat that kind of body temperature at about 37 ° C hold. In the sauna heats the skin faster than that of the body from about 32 ° C to about 42 ° C (after 20 minutes), while the body temperature by up to 1 to 2 ° centigrade. This is going to sweat production, causing the skin temperature drops in an attempt to slow the temperature rise. The drier the air around the body, the faster the sweat evaporates, and the faster it cools off. Simultaneously dilate blood vessels in the skin, letting the blood flow to the skin increases, and warm blood is removed and replaced by colder blood. This increases the internal temperature again. Where normally only 5 to 10% of the blood flowing through the skin, the sauna can reach 50-70%.
To preserve this mechanism, the heart starts pumping faster and increases the cardiac performance (cardiac output). The heart rate in the sauna is twice as high than the resting heart rate, while cardiac performance (the amount of blood the heart pumps per minute) two to three times may be greater. This roughly corresponds to an increase in cardiac performance during a long walk.
The effects on blood pressure are minimal: the diastolic blood pressure fell slightly, the systolic blood pressure remains fairly constant.
Besides the heat also causes the cooling phase for a load of cardiac function. That depends on the type of cooling. Immersion in ice water, the skin temperature drops very quickly from about 40 ° C to 33 ° C, while the body very rapidly with 1 to 2 ° Celsius to return to normal temperature. This leads to a rapid increase in blood pressure.

Moisture Loss
The moisture loss after a sauna session is approximately 0.5 to 1 liter Sweat contains less salt than blood and potassium, causing a slight increase in salt and potassium in the blood occurs. The concentration of hemoglobin (the red pigment in red blood cells) increases slightly. Hemoglobin is necessary for transporting oxygen from the lungs to the organs and tissues. The moisture loss is also the renin-angiotensin-aldosterone hormonal system prepayments. When this hormone system is ‘encouraged’ increases blood pressure, squeezing the blood vessels in the kidney and salt together and moisture retention.

Hormonal changes
Sauna has an impact on our hormones. Thus, the hypothalamic-pituitary-adrenal hormonal axis (HPA) axis is activated. As a result, a number of so-called stress hormones Fri put. In particular, there is an increased production of norepinephrine, prolactin, beta-endorphins and growth hormone. The production of cortisol, epinephrine, ACTH (adrenocorticotropic hormone or corticotropin) and testosterone (male sex hormone) remains virtually unchanged. This leads to a reduced pain sensation, increased alertness and a mild euphoria.
2. Health claims of (classical) sauna

Muscle and joint disorders / pain

Claims
- Sauna accelerates healing of muscle injuries by improving blood flow.
- Sauna has a beneficial effect in rheumatic complaints. This certainly applies to arthritis, involving pain and movement restrictions in joints and back and where we are tense and sore muscles.
- Sauna reduce gout symptoms
- Sauna has analgesic effect