J. Schmid
2018
Citations
0
Influential Citations
6
Citations
Quality indicators
Journal
European Journal of Preventive Cardiology
Abstract
In Finland, sauna bathing has been practised for centuries, either for pleasure, but more importantly also for reasons of hygiene and maintenance of health. Many curative and magical effects have been attributed to its practice and seldom has it been thought to cause any disease. In fact, in a general Finnish male population, sauna bathing has been shown to be a protective factor against the occurrence of sudden cardiac death, fatal coronary heart and cardiovascular disease, as well as all-cause mortality. While the short-term cardiovascular and hormonal effects of Finnish sauna are quite well studied, the long-term mechanisms are still incompletely understood. In contrast, another particular form of thermal therapy, developed in Japan and applied in the treatment of patients with cardiovascular disease for the past 20 years, is quite well studied: the so-called Waon therapy, ‘wa’ meaning soothing and ‘on’ meaning warmth. It is a dry sauna with a temperature maintained at 60 C and defined as a warming of the entire body in a uniformly heated chamber (far-infrared ray) for 15 minutes, increasing the core temperature by 1.0–1.2 C, followed by a 30-minute rest outside the sauna. Waon therapy has been reported to improve the haemodynamics, cardiac function, ventricular arrhythmia, vascular endothelial function, neurohormonal factors, sympathetic nervous system function and symptoms in patients with chronic heart failure and peripheral artery disease. The molecular mechanism by which Waon therapy improves vascular flow and endothelial function involves the increased expression of endothelial nitric oxide synthase. Due to the difference in temperature and humidity as well as the intermittent cooling during traditional Finnish sauna, the question of similar effects of this type of heat exposure compared with the milder form of Waon therapy remains. In this issue of the European Journal of Preventive Cardiology, Lee et al. now report about the effect of Finnish sauna on arterial compliance and the dynamics of blood flow and pressure. The experiment was conducted with a temperature of 73 2 and a relative humidity of 10–20%. One single 30-minute session, interspersed with a short, 2-minute shower after 15 minutes was performed in 102 asymptomatic participants with a mean age of 51.9 years and at least one cardiovascular risk factor. The study showed an improvement of different parameters of arterial stiffness (pulse wave velocity, mean blood pressure, left ventricular ejection time and diastolic time) and hence similar potential effects for long-term protection of cardiovascular function as does Waon therapy. Interestingly, these effects reported by heat exposure are the same as postulated by the practice of regular aerobic physical exercise, and one might suggest that sauna bathing could substitute for limited exercise options, e.g. during the winter months in Nordic countries or for exercise at all. To disentangle the potential interaction between exercise training and sauna practice, Kunutsor et al. evaluated 2277 men in a prospective study for the joint effects of cardiovascular fitness (low vs. high: median cutoffs) and frequency of sauna bathing (low vs. high: two or less and three to seven sessions/week) on the risk of fatal cardiovascular disease and all-cause mortality. During a median follow-up of 26.1 years, it turned out that cardiorespiratory fitness and frequency of sauna bathing are independently associated with a reduced mortality risk and that a combination of good cardiovascular fitness and frequent sauna bathing may confer additional survival benefits. Regarding the recommendations to practise Finnish sauna in patients with cardiovascular disease, due to the alternation between heat exposure and cold water immersion, there still remains concerns related to