Tanjaniina Laukkanen

Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events

IMPORTANCE Sauna bathing is a health habit associated with better hemodynamic function; however, the association of sauna bathing with cardiovascular and all-cause mortality is not known. OBJECTIVE To investigate the association of frequency and duration of sauna bathing with the risk of sudden cardiac death (SCD), fatal coronary heart disease (CHD), fatal cardiovascular disease (CVD), and all-cause mortality. DESIGN, SETTING, AND PARTICIPANTS We performed a prospective cohort study (Finnish Kuopio Ischemic Heart Disease Risk Factor Study) of a population-based sample of 2315 middle-aged (age range, 42-60 years) men from Eastern Finland. Baseline examinations were conducted from March 1, 1984, through December 31, 1989. EXPOSURES Frequency and duration of sauna bathing assessed at baseline. RESULTS During a median follow-up of 20.7 years (interquartile range, 18.1-22.6 years), 190 SCDs, 281 fatal CHDs, 407 fatal CVDs, and 929 all-cause mortality events occurred. A total of 601, 1513, and 201 participants reported having a sauna bathing session 1 time per week, 2 to 3 times per week, and 4 to 7 times per week, respectively. The numbers (percentages) of SCDs were 61 (10.1%), 119 (7.8%), and 10 (5.0%) in the 3 groups of the frequency of sauna bathing. The respective numbers were 89 (14.9%), 175 (11.5%), and 17 (8.5%) for fatal CHDs; 134 (22.3%), 249 (16.4%), and 24 (12.0%) for fatal CVDs; and 295 (49.1%), 572 (37.8%), and 62 (30.8%) for all-cause mortality events. After adjustment for CVD risk factors, compared with men with 1 sauna bathing session per week, the hazard ratio of SCD was 0.78 (95% CI, 0.57-1.07) for 2 to 3 sauna bathing sessions per week and 0.37 (95% CI, 0.18-0.75) for 4 to 7 sauna bathing sessions per week (P for trend = .005). Similar associations were found with CHD, CVD, and all-cause mortality (P for trend ≤.005). Compared with men having a sauna bathing session of less than 11 minutes, the adjusted hazard ratio for SCD was 0.93 (95% CI, 0.67-1.28) for sauna bathing sessions of 11 to 19 minutes and 0.48 (95% CI, 0.31-0.75) for sessions lasting more than 19 minutes (P for trend = .002); significant inverse associations were also observed for fatal CHDs and fatal CVDs (P for trend ≤.03) but not for all-cause mortality events. CONCLUSIONS AND RELEVANCE Increased frequency of sauna bathing is associated with a reduced risk of SCD, CHD, CVD, and all-cause mortality. Further studies are warranted to establish the potential mechanism that links sauna bathing and cardiovascular health.

Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men

Background there are no previous studies linking repeated heat exposure of sauna and the risk of memory diseases. We aimed to investigate whether frequency of sauna bathing is associated with risk of dementia and Alzheimers disease. Setting prospective population-based study. Methods the frequency of sauna bathing was assessed at baseline in the Kuopio Ischaemic Heart Disease population-based prospective cohort study of 2,315 apparently healthy men aged 42-60 years at baseline, with baseline examinations conducted between 1984 and 1989. Hazard ratios (HRs) with 95% confidence intervals (CIs) for dementia and Alzheimers disease were ascertained using Cox-regression modelling with adjustment for potential confounders. Results during a median follow-up of 20.7 (interquartile range 18.1-22.6) years, a total of 204 and 123 diagnosed cases of dementia and Alzheimers disease were respectively recorded. In analysis adjusted for age, alcohol consumption, body mass index, systolic blood pressure, smoking status, Type 2 diabetes, previous myocardial infarction, resting heart rate and serum low-density lipoprotein cholesterol, compared with men with only 1 sauna bathing session per week, the HR for dementia was 0.78 (95% CI: 0.57-1.06) for 2-3 sauna bathing sessions per week and 0.34 (95% CI: 0.16-0.71) for 4-7 sauna bathing sessions per week. The corresponding HRs for Alzheimers disease were 0.80 (95% CI: 0.53-1.20) and 0.35 (95% CI: 0.14-0.90). Conclusion in this male population, moderate to high frequency of sauna bathing was associated with lowered risks of dementia and Alzheimers disease. Further studies are warranted to establish the potential mechanisms linking sauna bathing and memory diseases.

Sauna Bathing and Incident Hypertension: A Prospective Cohort Study

BACKGROUND Sauna bathing is associated with reduced cardiovascular risk, but the mechanisms underlying this beneficial effect are not entirely understood. We aimed to assess the relationship between sauna bathing and risk of incident hypertension. METHODS Frequency of sauna bathing was ascertained using questionnaires in the Kuopio Ischemic Heart Disease Study, a prospective cohort study conducted in Eastern Finland that comprised a population-based sample of 1,621 men aged 42 to 60 years without hypertension at baseline. The incidence of hypertension was defined as a physician diagnosis of hypertension, systolic blood pressure (SBP) >140 mm Hg, diastolic blood pressure >90 mm Hg, or use of antihypertensive medication. RESULTS During a median follow-up of 24.7 years, 251 incident cases (15.5%) were recorded. In Cox regression analysis adjusted for baseline age, smoking, body mass index, and SBP; compared to participants reporting 1 sauna session per week, the hazard ratio for incident hypertension in participants reporting 2 to 3 sessions and 4 to 7 sessions was 0.76 (95% confidence interval: 0.57-1.02) and 0.54 (0.32-0.91), respectively. The corresponding hazard ratios were similar after further adjustment for glucose, creatinine, alcohol consumption, heart rate, family history of hypertension, socioeconomic status, and cardiorespiratory fitness: 0.83 (95% confidence interval: 0.59-1.18) and 0.53 (0.28-0.98), respectively. CONCLUSIONS Regular sauna bathing is associated with reduced risk of hypertension, which may be a mechanism underlying the decreased cardiovascular risk associated with sauna use. Further epidemiological and experimental studies could help elucidate the effects of sauna bathing on cardiovascular function.

Acute effects of sauna bathing on cardiovascular function

Emerging evidence suggests beneficial effects of sauna bathing on the cardiovascular system. However, the effects of sauna bathing on parameters of cardiovascular function and blood-based biomarkers are uncertain. We aimed to investigate whether sauna bathing induces changes in arterial stiffness, blood pressure (BP), and several blood-based biomarkers. We conducted an experimental study including 102 participants (mean age (SD): 51.9 (9.2) years, 56% male) who had at least one cardiovascular risk factor. Participants were exposed to a single sauna session (duration: 30 min; temperature: 73 °C; humidity: 10–20%). Cardiovascular as well as blood-based parameters were collected before, immediately after, and after 30-min recovery. Mean carotid–femoral pulse wave velocity was 9.8 (2.4) m/s before sauna and decreased to 8.6 (1.6) m/s immediately after sauna (p < 0.0001). Mean systolic BP decreased after sauna exposure from 137 (16) to 130 (14) mmHg (p < 0.0001) and diastolic BP from 82 (10) to 75 (9) mmHg (p < 0.0001). Systolic BP after 30 min recovery remained lower compared to pre-sauna levels. There were significant changes in hematological variables during sauna bathing. Plasma creatinine levels increased slightly from sauna until recovery period, whereas sodium and potassium levels remained constant. This study demonstrates that sauna bathing for 30 min has beneficial effects on arterial stiffness, BP, and some blood-based biomarkers. These findings may provide new insights underlying the emerging associations between sauna bathing and reduced risk of cardiovascular outcomes.

Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study

Objective To assess the association between frequency of sauna bathing and risk of future stroke. Methods Baseline habits of sauna bathing were assessed in 1,628 adult men and women aged 53–74 years (mean age, 62.7 years) without a known history of stroke in the Finnish Kuopio Ischemic Heart Disease prospective cohort study. Three sauna bathing frequency groups were defined: 1, 2–3, and 4–7 sessions per week. Hazard ratios (HRs) (95% confidence intervals [CIs]) were estimated for incident stroke. Results During a median follow-up of 14.9 years, 155 incident stroke events were recorded. Compared with participants who had one sauna bathing session per week, the age- and sex-adjusted HR (95% CI) for stroke was 0.39 (0.18–0.83) for participants who had 4–7 sauna sessions per week. After further adjustment for established cardiovascular risk factors and other potential confounders, the corresponding HR (95% CI) was 0.39 (0.18–0.84) and this remained persistent on additional adjustment for physical activity and socioeconomic status at 0.38 (0.18–0.81). The association between frequency of sauna bathing and risk of stroke was not modified by age, sex, or other clinical characteristics (p for interaction > 0.10 for all subgroups). The association was similar for ischemic stroke but modest for hemorrhagic stroke, which could be attributed to the low event rate (n = 34). Conclusions This long-term follow-up study shows that middle-aged to elderly men and women who take frequent sauna baths have a substantially reduced risk of new-onset stroke.

Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study

Abstract Purpose: We aimed to evaluate the joint impact of cardiorespiratory fitness (CRF) and frequency of sauna bathing (FSB) on the risk of cardiovascular and all-cause mortality. Design: CRF measured by respiratory gas analyses and sauna exposure were assessed at baseline in a prospective study of 2277 men. CRF was categorized as low and high (median cut-offs) and FSB as low and high (≤2 and 3–7 sessions/week, respectively). Results: During a median follow-up of 26.1 years, 520 cardiovascular and 1124 all-cause deaths occurred. Comparing high versus low CRF, the multivariate-adjusted hazard ratios (HRs) 95% CIs for cardiovascular and all-cause mortality were 0.51 (0.41–0.63) and 0.65 (0.57–0.75), respectively. Comparing high versus low FSB, the corresponding HRs were 0.74 (0.59–0.94) and 0.84 (0.72–0.97), respectively. Compared to low CRF & low FSB, the HRs of CVD mortality for high CRF & high FSB; high CRF & low FSB; and low CRF & high FSB were 0.42 (0.28–0.62), 0.50 (0.39–0.63) and 0.72 (0.54–0.97), respectively. For all-cause mortality, the corresponding HRs were 0.60 (0.48–0.76), 0.63 (0.54–0.74) and 0.78 (0.64–0.96), respectively. Conclusions: A combination of high CRF and frequent sauna bathing confers stronger long-term protection on mortality outcomes compared with high CRF or high FSB alone. KEY MESSAGES Cardiorespiratory fitness (CRF) and frequency of sauna bathing are independently associated with reduced mortality risk; a combination of good CRF and frequent sauna bathing may confer additional survival benefits. In a population-based prospective cohort study, a combination of high CRF levels and frequent sauna bathing (3–7 sessions per week) was associated with a substantial risk reduction in fatal cardiovascular and all-cause mortality events compared with good CRF or frequent sauna bathing alone. A combination of good fitness levels produced by aerobic exercises and frequent sauna bathing may have added health benefits and confer more protection on the risk of mortality.

Longitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort study

Abstract Purpose: We sought to determine cross-sectional and longitudinal associations of frequency of sauna bathing with high sensitivity C-reactive protein (hsCRP), fibrinogen, leucocyte count and gamma-glutamyltransferase (GGT). Design: Baseline sauna bathing habits were assessed in 2269 men aged 42–61 years. Concentrations of hsCRP, fibrinogen, leucocyte count, and GGT were determined at baseline and 11 years later. The associations of sauna bathing frequency with baseline and 11-year hsCRP, fibrinogen, leucocyte count, and GGT levels were examined using robust multivariate regression analyses. Results: In baseline analysis, 4–7 sauna sessions/week (compared with 1 sauna session/week) was associated with −0.84 mg/l (95% CI, −1.55, −0.14; p = .019) lower hsCRP; −0.07 g/l (95% CI, −0.15, 0.02; p = .112) lower fibrinogen; and −0.28 × 109/l (95% CI, −0.51, −0.06; p = .015) lower leucocyte count, after multivariable adjustment. In longitudinal analysis, the corresponding estimates were −1.66 mg/l (95% CI, −3.13, −0.19; p = .027); −0.16 g/l (95% CI, −0.31, −0.02; p = .031); and −0.49 × 109/l (95% CI, −0.85, −0.14; p = .007) respectively. Sauna bathing frequency was not associated with GGT at baseline and 11 years. Conclusion: Observational evidence supports the hypothesis that reduction in inflammation may be one of the pathways linking frequent sauna bathing with decreased risk of acute and chronic disease conditions. KEY MESSAGES Cross-sectional evidence or short-term studies suggest Finnish sauna bathing may exert its beneficial health effects via reduction in inflammation and oxidative stress; however, the long-term effects of sauna bathing on these outcomes are uncertain. In this population-based prospective cohort study, frequent sauna sessions significantly decreased levels of inflammatory markers at baseline and 11-year follow-up; but had no effect on oxidative stress. The health benefits of sauna bathing may in part be mediated via reduced systemic inflammation.

Combined Effect of Sauna Bathing and Cardiorespiratory Fitness on the Risk of Sudden Cardiac Deaths in Caucasian Men: A Long-term Prospective Cohort Study

Both cardiorespiratory fitness (CRF) and frequency of sauna bathing (FSB) are each strongly and independently associated with sudden cardiac death (SCD) risk. However, the combined effect of CRF and FSB on SCD risk has not been previously investigated. We evaluated the joint impact of CRF and FSB on the risk of SCD in the Kuopio Ischemic Heart Disease prospective cohort study of 2291 men aged 42-61 years at recruitment. Objectively measured CRF and self-reported sauna bathing habits were assessed at baseline. CRF was categorized as low and high (median cutoffs) and FSB as low and high (defined as ≤2 and 3-7 sessions/week respectively). Multivariable adjusted hazard ratios (HRs) with confidence intervals (CIs) were calculated for SCD. During a median follow-up of 26.1 years, 226 SCDs occurred. Comparing high vs low CRF, the HR (95% CIs) for SCD in analysis adjusted for several established risk factors was 0.48 (0.34-0.67). Comparing high vs low FSB, the corresponding HR was 0.67 (0.46-0.98). Compared to men with low CRF & low FSB, the multivariate-adjusted HRs of SCD for the following groups: high CRF & high FSB; high CRF & low FSB; and low CRF & high FSB were 0.31 (0.16-0.63), 0.49 (0.34-0.70), and 0.71 (0.45-1.10) respectively. In a general male Caucasian population, the combined effect of high aerobic fitness (as measured by CRF) and frequent sauna baths is associated with a substantially lowered risk of future SCD compared with high CRF or frequent sauna bathing alone.

Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence

&NA; Sauna bathing, an activity that has been a tradition in Finland for thousands of years and mainly used for the purposes of pleasure and relaxation, is becoming increasingly popular in many other populations. Emerging evidence suggests that beyond its use for pleasure, sauna bathing may be linked to several health benefits, which include reduction in the risk of vascular diseases such as high blood pressure, cardiovascular disease, and neurocognitive diseases; nonvascular conditions such as pulmonary diseases; mortality; as well as amelioration of conditions such as arthritis, headache, and flu. The beneficial effects of sauna bathing on these outcomes have been linked to its effect on circulatory, cardiovascular, and immune functions. It has been postulated that regular sauna bathing may improve cardiovascular function via improved endothelium‐dependent dilatation, reduced arterial stiffness, modulation of the autonomic nervous system, beneficial changes in circulating lipid profiles, and lowering of systemic blood pressure. This review summarizes the available epidemiological, experimental, and interventional evidence linking Finnish sauna bathing and its effects on cardiovascular outcomes and other disease conditions on the basis of a comprehensive search for observational studies, randomized controlled trials, and non–randomized controlled trials from MEDLINE and EMBASE from their inception until February 24, 2018. An overview of the postulated biological mechanisms underlying the associations between sauna bathing and its health benefits, areas of outstanding uncertainty, and implications for clinical practice is also provided.

Cardiorespiratory fitness is associated with reduced risk of future psychosis: A long-term prospective cohort study

Psychosis is a severe disabling condition and associated with increased morbidity as well as premature mortality (McGrath et al. 2008). Though little is known about the etiology of psychosis, it is a partly preventablemental illness and life-style factors have been implicated in its development. Cardiorespiratory fitness (CRF), as measured by maximal oxygen uptake (VO2max), is considered the gold standard for assessing aerobic capacity and is an index of cardiac and respiratory functioning (Noonan and Dean 2000). Cardiorespiratory fitness is well known to be strongly inversely and independently associated with the risk of cardiovascular disease (CVD) (Kodama et al. 2009) and allcause mortality (Kodama et al. 2009). Individuals with psychotic disorders have been shown to have lower CRF (Vancampfort et al. 2015). Accumulating evidence suggests that people with psychotic disorders such as schizophrenia are at high cardiovascular risk and CVDs are the major contributing factors for the increased mortality rates in these individuals (Olfson et al. 2015). Given that CRF is a major modifiable risk factor for CVD in the general population, we hypothesized that CRF could be related to the development of psychosis. In this context, we aimed to assess the association of CRF with future risk of psychosis, using a population-based cohort of 2212 Caucasian men, who were apparently free from any mental illness during baseline assessments. The current analysis employed the Finnish Kuopio Ischemic Heart Disease (KIHD) risk factor studywhich comprised a representative sample of middle-aged men aged 42–61 years recruited from eastern Finland. Details of recruitment methods, ethical permissions, and assessment of risk markers have been described in a previous report (Kunutsor et al. 2017). Maximal oxygen uptake was used as a measure of CRF, which was assessed using respiratory gas exchange analyzers during cycle ergometer exercise testing. Repeat measurements were performed several years apart in a random subset of participants. A detailed description of the measurement of VO2max has been reported elsewhere (Kunutsor et al. 2017). Data on hospitalizations due to psychotic disorders were ascertained by linkage to the National Hospital Discharge Register. The diagnoses of psychotic disorders were made by qualified psychiatrists and details have been previously described (Kunutsor and Laukkanen 2017). For the current analysis, men on antipsychoticmedication at study entry (n=54)were excluded. Hazard ratios (HRs) with 95% confidence intervals (CIs) for psychosis were calculated using Cox proportional hazardmodels. All statistical analyses