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Acute effects of sauna bathing on cardiovascular function

DOI:10.1038/s41371-017-0008-z
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Tanjaniina Laukkanen at University of Eastern Finland
Tanjaniina Laukkanen
Setor Kunutsor at University of Leicester
Setor Kunutsor
Francesco Zaccardi at University of Leicester
Francesco Zaccardi
Earric M Lee at University of Jyväskylä
Earric M Lee
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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.
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Journal of Human Hypertension (2018) 32:129–138
https://doi.org/10.1038/s41371-017-0008-z
ARTICLE
Acute effects of sauna bathing on cardiovascular function
Tanjaniina Laukkanen1●Setor K. Kunutsor2●Francesco Zaccardi 3●Earric Lee 4●Peter Willeit 5,6 ●
Hassan Khan7●Jari A. Laukkanen 1,8
Received: 1 July 2017 / Revised: 3 September 2017 / Accepted: 19 September 2017 / Published online: 21 December 2017
© Macmillan Publishers Limited, part of Springer nature 2018
Abstract
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.
Introduction
Sauna bathing, a form of passive heat therapy, is commonly
used for relaxation and pleasure purposes [1,2]. Repeated
sauna therapy has been shown to increase left ventricular
ejection fraction and reduce plasma levels of norepinephrine
and brain natriuretic peptide and increase the 6-min walk
distance [3]. After 1 week of repeated sauna exposure
(twice a day) in 10 healthy male volunteers, diastolic blood
pressure (DBP) was shown to decrease substantially [4].
Warm water immersion, which is also a form of passive
heat therapy, is associated with health benefits that include
improved endothelial and microvascular function as well as
reduced arterial stiffness (AS) and BP [5,6]. Passive heat
therapy (hot tub) improves cutaneous microvascular func-
tion by enhancing nitric oxide-dependent dilation in
sedentary humans [5]. It has been demonstrated that sauna
exposure results elevations in core temperature and changes
in cardiovascular hemodynamics, such as cardiac output
and vascular shear stress, which are similar to the effects of
exercise, and thus may provide an alternative means of
improving health [6]. In a 2-week trial of once-a-day
infrared-sauna exposure for patients with cardiovascular
*Jari A. Laukkanen
jariantero.laukkanen@uef.fi
1Institute of Public Health and Clinical Nutrition, University of
Eastern Finland, Kuopio, Finland
2Translational Health Sciences, Bristol Medical School, University
of Bristol, Learning and Research 11 Building (Level 1),
Southmead Hospital, Bristol, UK
3Diabetes Research Centre, Leicester General Hospital, University
of Leicester, Leicester, UK
4Department of Biology of Physical Activity, University of
Jyväskylä, Jyväskylä, Finland
5Department of Public Health and Primary Care, University of
Cambridge, Cambridge, UK
6Department of Neurology, Medical University Innsbruck,
Innsbruck, Austria
7Emory University, Atlanta, GA, USA
8Central Finland Health Care District, Department of Internal
Medicine, Jyväskylä, Finland
Electronic supplementary material The online version of this article
(https://doi.org/10.1038/s41371-017-0008-z) contains supplementary
material, which is available to authorized users.
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... Currently, different protocols for HA have been established. They usually consist either of a combination of exercise in heat at [25][26][27][28][29][30][31][32][33][34][35] • C and at an intensity of 50-60% of VO 2max or a heat exposure between 40 and 50 • C after exercise [9]. Nevertheless, other alternative strategies for exposure to heat at extreme temperatures intend to replace exercise stress with heat stress. ...
... However, it was performed after training, so participants would accumulate fatigue. Recent research suggests a 15-bpm increment after a 30 min exposure to 73 ± 2 • C in a sauna with an elevation of tympanic temperature from 36.4 ± 0.5 to 38.4 ± 0.7 • C [26]. In this research, the HR recorded at the end of the third set in S4 was 133.54 ± 21.34 bpm, showing exhaustion due to heat interval exposure and growth in Tcore around 1 • C and Tskin of 2 • C. In this investigation, interval heat stress would act as interval training with accumulated fatigue in each set [27]. ...
... Vuori (1988) reported that the workload of the heart is minor with heat stress than with exercise, despite also accelerating HR [36]. During heat stress, blood pressure does not increase as it does with exercise [26], suggesting that controlled heat stress may be another option for health benefits, even in people with cardiac pathologies. ...
Heart Rate and Body Temperature Evolution in an Interval Program of Passive Heat Acclimation at High Temperatures (100 ± 2 °C) in a Sauna
Article
Full-text available
Heat exposure provokes stress on the human body. If it remains constant, it leads to adaptations such as heat acclimation. This study aims to observe the evolution of heart rate (HR), core temperature (Tcore), and skin temperature (Tskin) in an intervallic program of exposure to extreme heat. Twenty-nine healthy male volunteers were divided into a control group (CG; n = 14) and an experimental group (EG; n = 15). EG experienced nine sessions (S) of intervallic exposure to high temperatures (100 ± 2 • C), whereas CG was exposed to ambient temperatures (22 ± 2 • C). HR, Tskin, and Tcore were monitored in S1, 4, 5, 8, and 9. An important increase in HR occurred in the S4 compared to the rest (p < 0.05) in EG. A lower HR was discovered in S8 and S9 compared to S4 and in S9 in relation to S1 (p < 0.05) in EG. EG experiences a gradual decrease in Tcore and Tskin, which was detected throughout the assessments, although it was only significant in the S8 and S9 (p < 0.05). Interval exposure to heat at 100 ± 2 • C elicits stress on the human organism, fundamentally increasing Tcore, Tskin, and FC. This recurring stress in the full program caused a drop in the thermoregulatory response as an adaptation or acclimation to heat.
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... [84][85][86] Based on numerous prior studies, beneficial cardiovascular responses such as decreases in SBP/DBP and arterial stiffness were expected to be observed with the sauna and exercise activities. 32,40,55,[87][88][89] Of note, these referenced studies were conducted predominantly with men and often involved CVD risk-afflicted populations. 32,40,55,87,88 Yet the blood pressure and arterial stiffness responses of our female participants were not significantly different across all three interventions, including control. ...
... 32,40,55,[87][88][89] Of note, these referenced studies were conducted predominantly with men and often involved CVD risk-afflicted populations. 32,40,55,87,88 Yet the blood pressure and arterial stiffness responses of our female participants were not significantly different across all three interventions, including control. However, we did not measure BPs during the interventions (only at baseline, immediately afterwards and post-recovery), unlike a recent study which tracked increases in HR and BP during a 25-min session of Finnish-style sauna (93 o C, 13% RH), followed by sustained decreases in BP afterwards. ...
Infrared Sauna as Exercise-mimetic? Physiological Responses to Infrared Sauna vs Exercise in Healthy Women: A Randomised Controlled Crossover Trial
Article
Full-text available
Background Passive heat therapies have been reported to have similar effects on the cardiovascular system as exercise. Studies supporting these findings in healthy populations have predominantly been done with men using warm water immersions or traditional saunas, rather than newer infrared-based saunas. Objective To explore short-term thermal and cardiovascular responses in women using an infrared sauna as compared to moderate-intensity exercise. Study design Randomised controlled crossover trial with balanced allocations. Setting Brisbane, Australia (August 2019 - March 2020) Participants Ten healthy women (36 ± 9 years) Interventions 45 minutes of resting, infrared sauna or indoor bicycling Primary outcome measures tympanic/skin temperatures; respiratory rate; blood pressure; arterial stiffness; heart rate variability Results Tympanic temperatures were elevated during infrared sauna as compared to both control (mean diff = +1.05 oC ± SEM 0.12 oC, 95% C.I.: 0.73 – 1.36, p < 0.0005) and exercise (mean diff = +0.79 oC ± SEM 0.12 oC, 95% C.I.: 0.49 – 1.08, p<0.0005). Respiratory rates were higher during exercise as compared to both control (mean diff = +7.66 ± SEM 1.37, 95% C.I.: 4.09 – 11.23, p < 0.0005) and infrared sauna (mean diff = +6.66 ± SEM 1.33, 95% C.I.: 3.20 – 10.11, p < 0.0005). No significant differences in non-invasive measures of blood pressure, arterial stiffness or heart rate variability were detected between any of the interventions. Conclusions These findings suggest the physiological effects of infrared sauna bathing are underpinned by thermoregulatory-induced responses, more so than exercise-mimetic cardiorespiratory or cardiovascular activations.
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... The experiments involve exposure of healthy participants to elevated temperatures using a personal, portable sauna chamber for 20 min. The decrease in BP and increase in arterial compliance would, based on the empirical theory referenced previously, lead to a corresponding increase in PAT consistent with reported studies based on applanation tonometry [61][62][63] . While this trend is modestly observed on initial exposure to heat, after profuse perspiration begins and BP decreases further around 10 min after entry into the sauna, the data from the system reported here and presented in Fig. 3b indicate that a consistent decrease in PAT is observed. ...
Synchronized wearables for the detection of haemodynamic states via electrocardiography and multispectral photoplethysmography
Article
Full-text available
Cardiovascular health is typically monitored by measuring blood pressure. Here we describe a wireless on-skin system consisting of synchronized sensors for chest electrocardiography and peripheral multispectral photoplethysmography for the continuous monitoring of metrics related to vascular resistance, cardiac output and blood-pressure regulation. We used data from the sensors to train a support-vector-machine model for the classification of haemodynamic states (resulting from exposure to heat or cold, physical exercise, breath holding, performing the Valsalva manoeuvre or from vasopressor administration during post-operative hypotension) that independently affect blood pressure, cardiac output and vascular resistance. The model classified the haemodynamic states on the basis of an unseen subset of sensor data for 10 healthy individuals, 20 patients with hypertension undergoing haemodynamic stimuli and 15 patients recovering from cardiac surgery, with an average precision of 0.878 and an overall area under the receiver operating characteristic curve of 0.958. The multinodal sensor system may provide clinically actionable insights into haemodynamic states for use in the management of cardiovascular disease.
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... Although HR was unaffected by HIIE with heat stress, the improved BP profile suggests a cardioprotective benefit to this exercise-heat paradigm, albeit only in a small group of individuals. However, this reduction in BP parallels that observed with long-term PHT protocols, which have demonstrated improvements in vascular function and BP regulation in various populations [52]. For example, Brunt et al. demonstrated a -10-mmHg improvement in MAP, owing to decreased arterial stiffness and improved endothelial function, with eight weeks of passive heat therapy in young sedentary adults [20]. ...
Impact of high intensity interval exercise with and without heat stress on cardiovascular and aerobic performance: a pilot study
Article
Full-text available
  • Jul 2023
Background Heat stress during aerobic exercise training may offer an additional stimulus to improve cardiovascular function and performance in a cool-temperate environment. However, there is a paucity of information on the additive effects of high-intensity interval exercise (HIIE) and acute heat stress. We aimed to determine the effects of HIIE in combination with acute heat stress on cardiovascular function and exercise performance. Methods Twelve active (peak O2 consumption [VO2peak]: 47 ± 8 ml·O2/min/kg) young adults were counterbalanced to six sessions of HIIE in hot (HIIE-H, 30 ± 1 °C, 50 ± 5% relative humidity [RH]) or temperate conditions (HIIE-T, 20 ± 2 °C, 15 ± 10% RH). Resting heart rate (HR), HR variability (HRV), central (cBP) and peripheral blood pressure (pBP), peripheral mean arterial pressure (pMAP), pulse wave velocity (PWV), VO2peak, and 5-km treadmill time-trial were measured pre- and post-training. Results Resting HR and HRV were not significantly different between groups. However, expressed as percent change from baseline, cSBP (HIIE-T: + 0.9 ± 3.6 and HIIE-H: -6.6 ± 3.0%, p = 0.03) and pSBP (HIIE-T: -2.0 ± 4.6 and HIIE-H: -8.4 ± 4.7%, p = 0.04) were lower in the heat group. Post-training PWV was also significantly lower in the heat group (HIIE-T: + 0.4% and HIIE-H: -6.3%, p = 0.03). Time-trial performance improved with training when data from both groups were pooled, and estimated VO2peak was not significantly different between groups (HIIE-T: 0.7% and HIIE-H: 6.0%, p = 0.10, Cohen’s d = 1.4). Conclusions The addition of acute heat stress to HIIE elicited additive adaptations in only cardiovascular function compared to HIIE alone in active young adults in temperate conditions, thus providing evidence for its effectiveness as a strategy to amplify exercise-induced cardiovascular adaptations.
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... Poziom kreatyniny w osoczu wzrósł nieznacznie od czasu kąpieli w saunie do okresu regeneracji,podczas gdy poziom sodu i potasu pozostał stały. Badanie to pokazuje, że kąpiel w saunie przez 30 minut ma korzystny wpływ na sztywność tętnic, ciśnienie tętnicze i niektóre biomarkery występujące we krwi[12].Badanie Brunt i wsp. sugeruje, że pasywna terapia ciepłem może stanowić skuteczną alternatywną metodę zmniejszania ryzyka sercowo-naczyniowego i śmiertelności w populacji pacjentów nie mogących wykonywać ćwiczeń fizycznych ze względów zdrowotnych np. ...
Sauna use as an activity leading to a reduction in modifiable risk factors for the development of hypertension - a systematic review
Article
Full-text available
  • Jun 2023
Background: Hypertension prevalence is disturbingly increasing all over the world. Clinicians and patients are looking for new pharmacological as well as non-pharmacological methods to help fight too-high blood pressure. Aim of this study: The aim of this study is to present the current scientific literature on the potential that sauna bathing may help lower blood pressure, but additional data are needed to confirm these findings. Material and methods: A systematic review of the scientific and medical literature from the PubMed and Google Scholar databases was carried out. This was achieved according to the keywords: hypertension, sauna and sauna bathing. Items of literature were qualified for analysis. State of knowledge: Using the sauna is a pleasant way to spend time, and additionally it can have an impact on lowering blood pressure. During a sauna session, the superficial vessels dilate, which leads to a short-term decrease in blood pressure. And long-term, more frequent sauna use leads to a reduced risk of hypertension. Using the sauna enhances the effect of pharmacotherapy and non-pharmacological methods of fighting hypertension, such as physical activity and a healthy, balanced diet. Most of the research on the above topic was conducted in Finland, where its use has a centuries-old tradition. Summary: Using the sauna has an impact on lowering blood pressure values, thanks to which it can support the treatment of hypertension. Sauna use may be an interesting way to lower blood pressure values in physically disabled people. More studies conducted on larger groups of patients and the influence of other factors on blood pressure values are needed to make more accurate recommendations.
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... (10) There is increasing evidence on the health benefits of frequent sauna bathing. Both epidemiological and intervention studies suggest that frequent Finnish sauna bathing may be protective of several adverse health outcomes (11)(12)(13)(14)(15)(16)(17). Higher frequency of sauna bathing is associated with reduced risk of cardiovascular outcomes such as hypertension (18), CVD mortality (19), stroke (20), dementia (21), as well as all-cause mortality (19). ...
The Interplay between Systolic Blood Pressure, Sauna Bathing, and Cardiovascular Mortality in Middle-Aged and Older Finnish Men: A Cohort Study
Article
Full-text available
Objectives Elevated systolic blood pressure (SBP) is associated with an increased risk of cardiovascular disease (CVD) mortality, whereas frequent sauna bathing reduces the risk. Whether frequent sauna bathing mitigates CVD mortality among adults with elevated SBP has not been previously investigated.Design and SettingWe examined the interactions between SBP and frequency of sauna bathing (FSB) with the risk of CVD mortality in a cohort of Caucasian men.ParticipantsThe Kuopio Ischaemic Heart Disease Study cohort comprising of 2,575 men aged 42–61 years at baseline was employed for this prospective study analysis.MeasurementsResting blood pressure was measured using a standardized protocol and sauna bathing habits were assessed by a self-administered questionnaire. Systolic blood pressure was categorized as normal and high (<140 and ≥140 mmHg, respectively) and FSB as low and high (defined as ≤ 2 and 3–7 sessions/week, respectively).ResultsA total of 744 CVD deaths were recorded during a median follow-up of 27.8 yr. Comparing high vs normal SBP, the multivariable-adjusted HR (95% CI) for CVD mortality was 1.44 (1.23–1.68). Comparing low vs high FSB, the multivariable-adjusted HR (95% CI) for CVD mortality was 1.24 (1.03–1.51). The associations persisted following mutual adjustment for each exposure. Compared with men with normal SBP-high FSB, high SBP-low FSB was associated with an increased risk of CVD mortality 1.81 (1.39–2.36), with attenuated but persisting evidence of an association for men with high SBP and high FSB 1.52 (1.06–2.16). When SBP was categorized as normal and high (<130 and ≥130 mmHg, respectively), there was no evidence of an association for men with high SBP and high FSB 1.11 (0.77–1.61).Conclusion There might be an interaction between SBP, sauna bathing and CVD mortality risk in middle-aged and older Caucasian males. Frequent sauna baths may offset the increased risk of CVD mortality in men with high-normal SBP but not elevated SBP.
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The reliability of a portable steam sauna pod for the whole-body passive heating of humans
Article
Full-text available
Introduction: Passive heating is receiving increasing attention within human performance and health contexts. A low-cost, portable steam sauna pod may offer an additional tool for those seeking to manipulate physiological (cardiovascular, thermoregulatory and sudomotor) and perceptual responses for improving sporting or health profiles. This study aimed to 1) report the different levels of heat stress and determine the pods’ inter-unit reliability, and 2) quantify the reliability of physiological and perceptual responses to passive heating. Method: In part 1, five pods were assessed for temperature and relative humidity (RH) every 5min across 70min of heating for each of the 9 settings. In part 2, twelve males (age: 24±4years) completed two 60min trials of passive heating (3x20min at 44°C/99% RH, separated by 1 week). Heart rate (HR), rectal (Trectal) and tympanic temperature (Ttympanic) were recorded every 5min, thermal comfort (Tcomfort) and sensation (Tsensation) every 10min, mean arterial pressure (MAP) at each break period and sweat rate (SR) after exiting the pod. Results: In part 1, setting 9 provided the highest temperature (44.3±0.2°C) and longest time RH remained stable at 99% (51±7min). Inter-unit reliability data demonstrated agreement between pods for settings 5-9 (intra-class correlation [ICC]>0.9), but not for settings 1-4 (ICC<0.9). In part 2, between-visits, high correlations, and low typical error of measurement (TEM) and coefficient of variation (CV) were found for Trectal, HR, MAP, SR, and Tcomfort, but not for Ttympanic or Tsensation. A peak Trectal of 38.09±0.30°C, HR of 124±15b.min-1 and a sweat loss of 0.73±0.33L were reported. No between-visit differences (p>0.05) were observed for Trectal, Ttympanic, Tsensation or Tcomfort, however HR (+3b.min-1) and MAP (+4mmHg) were greater in visit 1 vs. 2 (p<0.05). Conclusion: Portable steam sauna pods generate reliable heat stress between-units. The highest setting (44°C/99% RH) also provides reliable but modest adjustments in physiological and perceptual responses.
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Injuries related to sauna bathing
Article
Purpose: Awareness of well-being and health issues have contributed to increased popularity of sauna bathing. However, little is known about potential risks and injuries. The aim of this study was to identify the causes for injuries, the affected body regions and to define recommendations for prevention. Methods: A retrospective chart data analysis was conducted among patients treated for an injury related to sauna bathing at the local trauma centre of the Medical University of Innsbruck between January 1, 2005 and December 31, 2021. Patients' demographics, the cause for the injury, the diagnosis, the body region of the trauma and the treatment methods were collected. Results: Two hundred and nine patients with injuries related to sauna bathing (83 female [39.7%] and 126 male [60.3%]) were identified. Fifty-one patients showed more than one injuries leading to a total of 274 diagnosis: contusions/distorsions (113; 41.2%), wounds (79; 28.8%), fractures (42; 15.3%), ligament injuries (17; 6.2%), concussions (15; 5.5%), burns (4; 1.5%) and brain bleeding (3; 1.1%). The most common cause for an injury was a slip/fall (157; 57.5%) followed by dizziness/syncope (82; 30.0%). Interestingly, head and face injuries were mostly caused by dizziness/syncope, whereas slip/fall was the leading cause for injuries of foot, hand, forearm and wrist. Nine patients(4.3%) needed surgical treatment mainly due to fractures. Eight patients got injured by wood splinters. One patient sustained grade IIB-III burns lying unconscious with an alcohol intoxication of 3.6‰ in the sauna. Conclusion: The main causes for injuries during sauna bathing were slip/falls and dizziness/syncopes. The latter one might be prevented by improved of the personal behaviour (e.g. drink enough water before and after each sauna bathing), whereas slip/falls might be prevented by the revision of safety regulations, particularly the obligation to wear slip resistant slippers. Thus, everyone himself as well as the operators can contribute to reduce injuries related sauna bathing.
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Sauna bathing, renal function and chronic kidney disease: Cross‐sectional and longitudinal findings from the KIHD study
Article
Background: It is uncertain if passive heat therapies are associated with adverse renal outcomes. We sought to evaluate the cross-sectional and longitudinal associations of the frequency of sauna bathing with renal function measures and chronic kidney disease (CKD). Material and methods: Baseline self-reported sauna bathing habits were assessed in 2071 men aged 42-61 years with normal kidney function. Baseline estimated glomerular filtration rate (GFR) and serum levels of creatinine, potassium (K) and sodium (Na) were measured, with only 11-year measurements of K and Na 11 years in a random subset of participants due to logistical reasons. Study participants were followed up for CKD diagnosed using KDOQI guidelines, which were collected from the National Hospital Discharge Registry. The associations of frequency of sauna bathing with renal function measures were evaluated using regression analyses. Hazard ratios (HRs) (95% CIs) were estimated for CKD. Results: There were no significant changes in baseline levels of estimated GFR, creatinine and Na comparing 4-7 sauna sessions/week vs 1 sauna session/week; there was a slight increase in K 0.05 mmol/l (95% CI, 0.00, 0.10; p=0.033). There were no significant changes in levels of serum K and Na at 11 years. After 25.7 years overall median follow-up, 188 CKD cases were recorded. Comparing 4-7 sauna sessions/week with 1 sauna session/week, there was no evidence of an association with CKD 0.84 (95% CI, 0.46-1.53; p=.56). Conclusions: Cross-sectional and longitudinal observational evidence suggests that frequent sauna bathing is not associated with impaired renal function or the future risk of CKD.
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Benefits of sauna on lung capacity, neurocognitive diseases, and heart health
Article
Full-text available
  • Jan 2023
Sauna refers to passive heat therapy that involves exposure of the body to a high-temperature environment for an appropriately short period, contingent on the therapy’s purpose. Ideally, the therapy aims to raise the internal body temperature by a few degrees, and its effect happens in two phases. The first phase occurs during the first ten minutes, encouraging the body to perspire while maintaining a temperature of around 98.6 degrees. The extra heat is dispersed by increased blood circulation, blood pushing on the skin's surface, and sweating. The body enters the second phase after 10-30 minutes in the sauna. During this period, the body cannot disperse the sauna heat, thereby increasing the body temperature. In return, the heart rate and sweating increase. There are four different types of saunas. These include traditional saunas, usually heated with wood-burning stoves, rocks, or an electric coil. Far-infrared saunas are usually heated by metallic or ceramic elements that produce a small spectrum of light, referred to as far-infrared. Infrared lamp saunas are heated using heat lamps that produce radiant heat. The last type is steam saunas, traditionally heated, but water increases the humidity and air temperatures. During sauna therapy, the heart rate of an individual increase from the standard range up to 120 or 150 beats per minute. Unlike physical activity, sauna therapy does not involve any active function of the skeletal muscles. Even though skeletal muscles are inactive during a sauna session, blood volume is partially redirected to the internal organs' exterior body parts due to decreased venous return. Sauna therapy assists in liberating toxins piled in our tissues, facilitating lymph and blood circulation and strengthening one's immune system. Sauna bathing has mainly been used for purposes of relaxation and pleasure. Today, the activity is increasingly becoming popular as a form of treatment therapy. Several pieces of evidence claim that sauna bathing has numerous health benefits, including hemodynamic regulation processes, reduced risk of vascular diseases, cardiovascular disease, neurocognitive diseases, mortality, pulmonary diseases, stabilized arterial blood pressure, and enhancement of conditions such as flu, headache, and arthritis. However, response to stress from heat can increase muscle blood flow. This report will precisely explore the benefits of sauna bathing on lung capacity and heart health for people with cardiovascular, lung-related or respiratory-related, and neurocognitive diseases.
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Sauna Bathing and Incident Hypertension: A Prospective Cohort Study
Article
Full-text available
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.
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Passive heat therapy improves cutaneous microvascular function in sedentary humans via improved nitric oxide-dependent dilation
Article
Full-text available
  • Jul 2016
Methods: Eighteen young, sedentary, otherwise healthy subjects participated in 8 weeks of heat therapy (hot water immersion to maintain rectal temperature ≥38.5°C for 60min per session; N=9) or thermoneutral water immersion (sham; N=9), and participated in experiments before and after the 8-week intervention in which forearm cutaneous hyperemia to 39°C local heating was assessed at three microdialysis sites receiving 1) Lactated Ringer's (Control), 2) Nω-nitro-L-arginine (L-NNA, non-specific NO synthase inhibitor), and 3) Tempol, a superoxide dismutase mimetic. The arm used for microdialysis experiments remained out of the water at all times. Data are mean±S.E. cutaneous vascular conductance (CVC = laser Dopper flux/mean arterial pressure), presented as percent maximal CVC (%CVCmax). Results: Heat therapy increased local heating plateau from 42±6 to 53±6%CVCmax (p<0.001) and increased NO-dependent dilation (difference in plateau between Control and L-NNA sites) from 26±6 to 38±4%CVCmax (p<0.01), while no changes were observed in the sham group. When data were pooled across all subjects at 0wks, Tempol had no effect on the local heating response (p=0.53 vs. Control). There were no changes at the Tempol site across interventions (p=0.58). Conclusions: Passive heat therapy improves cutaneous microvascular function by improving NO-dependent dilation, which may have clinical implications.
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Passive heat therapy improves endothelial function, arterial stiffness, and blood pressure in sedentary humans
Article
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Methods: Twenty young, sedentary subjects were assigned to participate in 8 weeks (4-5x/week) of heat therapy (N = 10; immersion in a 40.5°C bath sufficient to maintain rectal temperature ≥ 38.5°C for 60 min per session) or thermoneutral water immersion (N = 10; sham). Results: Eight weeks of heat therapy increased flow-mediated dilation from 5.6 ± 0.3% to 10.9 ± 1.0% (P < 0.01) and superficial femoral dynamic arterial compliance from 0.06 ± 0.01 to 0.09 ±0.01 mm(2) mmHg(-1) (P = 0.03), and reduced (i.e., improved) aortic pulse wave velocity from 7.1 ± 0.3 to 6.1 ± 0.3 m sec(-1) (P = 0.03), carotid intima media thickness from 0.43 ± 0.01 to 0.37 ± 0.01 mm (P < 0.001), and mean arterial blood pressure from 83 ± 1 to 78 ± 2 mmHg (P = 0.02). No changes were observed in the sham group or for carotid arterial compliance, superficial femoral intima media thickness or endothelium-independent dilation. Conclusions: Heat therapy improved endothelium-dependent dilation, arterial stiffness, intima media thickness, and blood pressure, indicating improved cardiovascular health. These data suggest heat therapy may provide a simple and effective tool for improving cardiovascular health in various populations. This article is protected by copyright. All rights reserved.
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Health effects and risks of sauna bathing
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  • Jun 2006
Objectives. To study physiological, therapeutic and adverse effects of sauna bathing with special reference to chronic diseases, medication and special situations (pregnancy, children). Study design. A literature review. Methods. Experiments of sauna bathing were accepted if they were conducted in a heated room with sufficient heat (80 to 90 degrees C), comfortable air humidity and adequate ventilation. The sauna exposure for five to 20 minutes was usually repeated one to three times. The experiments were either acute (one day), or conducted over a longer period (several months). Results. The research data retrieved were most often based on uncontrolled research designs with subjects accustomed to bathing since childhood. Sauna was well tolerated and posed no health risks to healthy people from childhood to old age. Baths did not appear to be particularly risky to patients with hypertension, coronary heart disease and congestive heart failure, when they were medicated and in a stable condition. Excepting toxemia cases, no adverse effects of bathing during pregnancy were found, and baths were not teratogenic. In musculoskeletal disorders, baths may relieve pain. Medication in general was of no concern during a bath, apart from antihypertensive medication, which may predispose to orthostatic hypotension after bathing. Conclusions. Further research is needed with sound experimental design, and with subjects not accustomed to sauna, before sauna bathing can routinely be used as a non-pharmacological treatment regimen in certain medical disorders to relieve symptoms and improve wellness.
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Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events
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  • Feb 2015
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. 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. 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. Frequency and duration of sauna bathing assessed at baseline. 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. 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.
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Effect of sauna-based heat acclimation on plasma volume and heart rate variability
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  • Nov 2014
We investigated the effect of post-exercise sauna bathing on plasma volume (PV) expansion and whether such responses can be tracked by changes in heart rate (HR)-based measures. Seven, well-trained male cyclists were monitored for 35 consecutive days (17 days baseline training, 10 days training plus sauna, 8 days training). Sauna exposure consisted of 30 min (87 °C, 11 % relative humidity) immediately following normal training. Capillary blood samples were collected while resting seated to assess PV changes. HR (HRwake) and vagal-related HR variability (natural logarithm of square root mean squared differences of successive R-R intervals, ln rMSSDwake) were assessed daily upon waking. A sub-maximal cycle test (5 min at 125 W) was performed on days 1, 8, 15, 22, 25, 29, and 35 and HR recovery (HRR60s) and ln rMSSDpostex were assessed post-exercise. Effects were examined using magnitude-based inferences. Compared with baseline, sauna resulted in: (1) peak PV expansion after four exposures with a likely large increase [+17.8 % (90 % confidence limits, 7.4; 29.2)]; (2) reduction of HRwake by a trivial-to-moderate amount [-10.2 % (-15.9; -4.0)]; (3) trivial-to-small changes for ln rMSSDwake [4.3 % (1.9; 6.8)] and ln rMSSDpostex [-2.4 % (-9.1; 4.9)]; and (4) a likely moderate decrease in HRR60s [-15.6 % (-30.9; 3.0)]. Correlations between individual changes in PV and HR measures were all unclear. Sauna bathing following normal training largely expanded PV in well-trained cyclists after just four exposures. The utility of HR and HRV indices for tracking changes in PV was uncertain. Future studies will clarify mechanisms and performance benefits of post-training sauna bathing.
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Lower-limb hot-water immersion acutely induces beneficial hemodynamic and cardiovascular responses in peripheral arterial disease and healthy, elderly controls
Article
Passive heat induces beneficial perfusion profiles, provides substantive cardiovascular strain and reduces blood pressure, thereby holding potential for healthy and cardiovascular disease populations. The aim of this study was to assess acute responses to passive heat via lower-limb hot-water immersion in patients with peripheral arterial disease (PAD) and healthy, elderly controls. Eleven patients with PAD (age 71±6 y, 7 male) and ten Controls (age 72±7 y, 8 male) underwent hot-water immersion (30 min waist-level immersion in 42.1±0.6°C water). Before, during and following immersion, brachial and popliteal artery diameter, blood flow and shear stress were assessed using duplex ultrasound. Lower-limb perfusion was measured also using venous occlusion plethysmography and near-infrared spectroscopy. During immersion, shear rate increased (p<0.0001) comparably between groups in the popliteal artery (Controls: +183±26%; PAD: +258±54%) and brachial artery (Controls: +117±24%; PAD: +107±32%). Lower-limb blood flow increased significantly in both groups, as measured from duplex ultrasound (>200%), plethysmography (>100%) and spectroscopy, while central and peripheral pulse wave velocity decreased in both groups. Mean arterial blood pressure was reduced by 22±9 mmHg (main effect p<0.0001, interaction p=0.60) during immersion, and remained 7±7 mmHg lower 3 h afterward. In PAD, popliteal shear profiles and claudication both compared favourably with those measured immediately following symptom-limited walking. A 30-min hot-water immersion is a practical means of delivering heat therapy to PAD patients and healthy, elderly individuals to induce appreciable systemic (chronotropic and blood pressure lowering) and hemodynamic (upper and lower-limb perfusion and shear rate increases) responses.
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Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men
Article
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 Alzheimer's 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 Alzheimer's 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 Alzheimer's 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 Alzheimer's 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 Alzheimer's disease. Further studies are warranted to establish the potential mechanisms linking sauna bathing and memory diseases.
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Health Benefits of Sauna Bathing
Article
  • Feb 2015
Often I have advised a patient who was considering an unnecessary test, such as a coronary artery calcium test or carotid ultrasonography from a mobile van, to forgo that test and instead spend the money on something that he or she would actually enjoy, such as a massage or spa treatment. In this issue, Laukkanen et al¹ present data indicating that my advice would not only help my patients feel good but would also, if they chose to regularly use a sauna bath, help them live longer. Analyzing data from the Finnish Kuopio Ischemic Heart Disease Study, the authors found that men who took more frequent saunas (4-7 times per week) actually live longer than once-per-week users. Although we do not know why the men who took saunas more frequently had greater longevity (whether it is the time spent in the hot room, the relaxation time, the leisure of a life that allows for more relaxation time, or the camaraderie of the sauna), clearly time spent in the sauna is time well spent.
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Comparison of the Microlife Blood Pressure Monitor With the Omron Blood Pressure Monitor for Detecting Atrial Fibrillation
Article
Screening for atrial fibrillation (AF) by assessing the pulse is recommended in high risk patients. Some clinical trials demonstrated that the Microlife blood pressure monitor (BPM) with AF detection is more accurate than pulse palpation. This led to a change in practice guidelines in the UK where AF screening with the Microlife device is recommended instead of pulse palpation. Many BPMs have irregular heart beat detection (IHD) but they have not been shown to detect AF reliably. Recently, one study, in a highly select population, suggested that the Omron BPM with IHD has a higher sensitivity for AF than the Microlife BPM. We compared the Microlife and the Omron BPMs to ECG readings for AF detection in general cardiology patients. Inclusion criteria were age >50 without a pacemaker or defibrillator. A total of 199 subjects were enrolled, 30 with AF. Each subject had a 12-lead ECG, one Omron BPM reading and three Microlife BPM readings as per device instructions. The Omron device had a sensitivity of 30% (95% confidence interval (CI) 15.4%-49.1%) with the sensitivity for the first Microlife reading of 97% (95% CI 81.4%-100%) and the Microlife readings using the majority rule (AF positive if at least two out of three individual readings positive for AF) of 100% (95% CI 85.9%-100%). Specificity for the Omron device was 97% (95% CI 92.5%-99.2%) and for the first Microlife reading of 90% (95% CI 83.8%-94.2%%) and for the majority rule Microlife device 92% (95% CI 86.2%-95.7%) (p<.0001). The specificity of both devices is acceptable but only the Microlife BPM has a sensitivity value that is high enough to be used for AF screening in clinical practice.
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