SCIENCE FRIDAY: FREQUENT SAUNA BATHS

Sauna by annchristin, taken September 13,2006 https://flic.kr/p/npBH6

THE HEALTH BENEFITS TO BE GAINED FROM TAKING SAUNA BATHS HAVE BEEN STUDIED BY SCANDIANVIAN RESEARCHERS for years. This week another study was released which might boost resolve to pay for a fitness center membership just for the sauna use.
 
Scientists from the University of Eastern Finland published a study in the journal Neurology which found that among both men and women participants who took saunas, those who visited 4-7 times per week had a 61% lower risk of stroke than those who visited once a week. 
 
The effect on stroke prevention was first noted when 2-3 sauna baths/week were taken, associated with a 14% stroke reduction. Thus, the more saunas per week, the greater the effect, strengthening the association.
 
After making adjustments for “established cardiovascular risk factors and other potential confounders like physical activity and socio-economic status”, the results did not change.  The “association between frequency of sauna bathing and risk of stroke” persisted and “was not modified by age, sex, or other clinical characteristics.”
 
The study followed 1,628 men and women* subjects in the Finnish Kuopio Ischemic Heart Disease Risk Factor prospective cohort study, who self-reported their sauna bathing frequency. They were aged 53-74 years (mean 62.7 years), followed over roughly 15 (14.9) years, and without a known history of stroke at the time of enrollment. Data was collected on blood pressure, body mass index, blood lipids, smoking habits, and alcohol intake.  Other information regarding participant characteristics that effect health was obtained, including exercise level and socio-economic status. 
 
Three sauna bathing frequency groups were studied 1, 2-3, and 4-7 sessions per week. The full study was not available to Earned Runs.  It would be helpful to have a comparison group of Finnish persons who did not regularly take saunas, as well as other details about race/ethnicity. An editorial, discussed below, seems to indicate that it would be uncommon for a person in Finland NOT to take a sauna at least once a week. The editorial doesn’t describe an average sauna session in terms of length of time or other parameters.
 
Previous scientific studies have demonstrated that having a sauna ‘habit’ may be good for health. Regular sauna bathing has been linked to a lowered risk of heart disease and sudden cardiac death, and a later onset of Alzheimer’s disease and dementia. The possible mechanisms underlying these effects involve reducing blood pressure and improving the function of the heart and circulatory system, achieved by the making arterial walls more compliant (less stiff), and stimulating the immune system.
 
[In one experimental study, the heat (73 degrees Celcius (10-20% humidity) of a 30-minute sauna session lead to a two-degree increase in body temperature in subjects and a rise in heart rate equivalent to what occurs with moderate exercise.]
 
An editorial in the same journal by Josef G. Heckmann and Katriina Kukkonen-Harjula,
explains the long tradition of sauna bathing in Finland and other “circumpolar countries”. In Finland, it says there are about 1 million saunas used by 5.5 million people! The practice starts in childhood; most Finns take one sauna/week as a “method of hardening” their bodies and increasing resistance.  The editorial’s author references beliefs that the positive effects of sauna bathing include prevention and treatment of diabetes and cardiovascular disease, improved nervous system health, blood lipid reduction, boosted antioxidant activity, and musculoskeletal pain relief.  Improved well-being from the feelings of pleasure and social camaraderie are also cited as benefits. Other studies of the same FKIHD subjects reported decreased risk of pneumonia and chronic pulmonary disease (COPD and asthma in middle-aged Caucasian men.
 
Because the studied population in the FKIHD research is Finnish, often men-only, it’s not certain that this warming therapy will result in the same benefits for all groups. However, to recreate this longitudinal research in other non- Scandinavian cultures could be nearly impossible (where else do you find people who have taken a daily sauna, since childhood?).  Other investigations can provide more information on acute effects and mechanisms perhaps. The safety guidelines for children or persons with pre-existing medical conditions, not discussed in the abstract, need to be established. 
 
On the surface, sauna bathing seems like an enjoyable and relaxing medical prescription for prevention and sometimes treatment of quite a few ailments. 
 
If it’s safe for me, I’m in!
 
RUN & MOVE HAPPY!
 
https://www.nytimes.com/2018/05/02/well/live/saunas-may-reduce-stroke-risk.html
 
https://yle.fi/uutiset/osasto/news/study_regular_sauna_bathing_significantly_reduces_the_risk_of_stroke/10188716
 
https://yle.fi/uutiset/osasto/news/sauna_improves_health_by_lowering_blood_pressure_and_artery_stiffness_study_finds/10010271
 
http://n.neurology.org/content/early/2018/05/02/WNL.0000000000005606
 
http://n.neurology.org/content/early/2018/05/02/WNL.0000000000005592
 
https://link.springer.com/article/10.1007%2Fs10654-017-0311-6

https://1www.ncbi.nlm.nih.gov/pubmed/29229091

*FKIHD Risk Factor Study enrolled men only according to the official descriptions. https://www.uef.fi/en/web/nutritionepidemiologists/kuopio-ischaemic-heart-disease-risk-factor-study-kihd-1984-
 
Women seem to have been included in the study but details are not found.  https://clinicaltrials.gov/ct2/show/NCT03221127