For the Finns it is part of everyday life, for us it is most likely to be found in a thermal bath, in the wellness area of a good hotel or in a well-equipped gym - the sauna. But also in our country more and more people appreciate the sauna or the steam bath and enjoy the pleasant warmth again and again, especially in the cold winter months. In addition to the relaxing effect, science has now been able to uncover other health-promoting aspects of sauna bathing.
The sauna and the steam bath:
Finnish sauna culture has been a UNESCO intangible cultural heritage site since 2020. However, sweating for cleansing, relaxation or healing had also been part of many other cultures. What they have in common is that the body is passively exposed to a high temperature for a short time. Temperatures of 45-100°C are typically used. While a Finnish sauna usually aims for 80-90°C and a comparatively low humidity (10-20%), a steam bath involves sweating at about 60°C and a humidity of over 50%. Due to the high humidity and the thus limited own cooling of the body, the steam bath is subjectively perceived as warmer and represents a greater burden for the cardiovascular system.
Hormesis:
In both cases a briefly increased core body temperature is achieved, like it is the case with physical activity. The body reacts to this not only with an increased sweating rate, but also with an increase in cardiac output (increase in heart rate for the same stroke volume) and an increase in blood plasma volume to cool the body. Regular sauna use leads to acclimatization and improved body response to future heat exposures, which can be explained by the biological model of hormesis. Hormesis describes that a small dose of a stressor has a positive, adaptive effect on the organism, which can make it more resistant to a new stress. This principle also explains why we become stronger or more enduring through regular exercise. Hormesis as a result of sauna bathing also leads to a number of other protective mechanisms within the body, often comparable to moderate to intense aerobic intensity exercise.
The effects in the body:
If there is an increase in core body temperature in the body, there is an increased release of so-called heat shock proteins. These proteins are of great importance for many cellular processes and immune function. They not only protect our existing cells from denaturation under stressful environmental conditions, but also assist in the repair or degradation of defective, non-functional cells and proteins. In addition to heat shock proteins, the immune system also responds to heat exposure with regulation of various pro- and anti-inflammatory messengers (e.g. the cytokines IL-6 and IL-10). On the hormonal level, increased levels of plasma renin, cortisol and growth factors can be observed. These have the task of regulating blood pressure and fluid volume, controlling metabolic processes for the provision of energy, or promoting the growth of muscles and soft tissue.
Influence of sauna on our health:
Various health-promoting aspects can also be derived from these acute adaptive reactions to sauna bathing and proven by scientific studies. Some of these reactions resemble those of physical exertion. For example, heart rate and blood pressure increase during the sauna session. Afterwards, however, the values drop back below the initial level. In the long run, there seems to be an improvement in blood pressure levels thanks to improved ejection rate of the ventricles and more dynamic blood vessel function. Furthermore, heat exposure is associated with alleviations of pain and symptoms in musculoskeletal conditions such as osteoarthritis, rheumatoid arthritis and fibromyalgia.
The benefits for our performance:
In addition to the health aspects, an influence of sauna bathing on physical performance can also be seen. Improved endurance performance can be explained by the increase in blood plasma and red blood cells. The heat shock protein already described may also contribute to preventing muscle breakdown during inactivity, releasing growth hormones, and improving insulin sensitivity due to its cell-protective properties.
Contraindications to going to the sauna:
Consequently, going to the sauna provides positive benefits to the body and is generally considered safe. Nevertheless there are contraindications where sauna bathing should be avoided, such as acute illness. If you are taking medication, a doctor should be contacted in advance for clarification. This also applies to people with diseases of the cardiovascular system. Children should not enter the sauna before the age of 12 because of their lower sweat rate. Pregnant women should also refrain from using the sauna, as it has not been sufficiently clarified what influence the high temperatures may have on the development of the fetus.
If you have any questions about the sauna or would like to try it out, please contact your inicio team in Basel or Kaiseraugst.
Literature:
Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence. (2018). J.A. Laukkanen et al
Sauna use as a lifestyle practice to extend healthspan. (2021). R.P. Patrick und T.L. Johnson
Elevating body temperature to reduce chronic low-grade inflammation: a welcome strategy for those unable to exercise? (2020). S.P. Hoekstra et al.