Sauna bathing and mortality risk: unraveling the interaction with systolic blood pressure in a cohort of Finnish men

Objectives: This cohort study aimed to investigate the potential interplay between systolic blood pressure (SBP), frequency of sauna bathing (FSB), and all-cause mortality risk among Caucasian men. Design: A prospective study was conducted, involving 2575 men aged 42 to 61 years. Baseline assessments included resting blood pressure measurements and self-reported sauna bathing habits. SBP levels were categorized as normal (<140 mmHg) or high (≥140 mmHg), while FSB was classified as low (≤2 sessions/week) or high (3-7 sessions/week). Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox regression analysis, while adjusting for lifestyle factors, lipids, inflammation, and comorbidities. Results: Over a median follow-up of 27.8 years, 1,618 deaths were recorded. In the adjusted analysis, individuals with high SBP versus low SBP showed a 29% increased all-cause mortality risk (HR 1.29, 95% CI 1.16-1.43). Similarly, those with low FSB versus high FSB exhibited a 16% elevated mortality risk (HR 1.16, 95% CI 1.02-1.31). When considering combined effects, participants with high SBP-low FSB had a 47% higher mortality risk (HR 1.47, 95% CI 1.24-1.74) compared to those with normal SBP-high FSB. However, no significant association was observed between individuals with high SBP-high FSB and mortality risk (HR 1.24, 95% CI 0.98-1.57). There were potential additive and multiplicative interactions between SBP and sauna bathing concerning mortality risk. Conclusions: This study reveals a potential interplay between SBP, sauna bathing, and mortality risk in Finnish men. Frequent sauna bathing may mitigate the increased mortality risk associated with elevated SBP.

A post-exercise infrared sauna session improves recovery of neuromuscular performance and muscle soreness after resistance exercise training

The aim of this study was to investigate effects of a single infrared sauna (IRS) session on post-exercise recovery of neuromuscular performance, autonomic nervous system function, subjective sleep quality, and muscle soreness. Male basketball players (n = 16) performed two trials consisting of a complex resistance exercise protocol (maximal strength with plyometrics), followed by either 20 min passive recovery (PAS) or IRS (temperature 43 ± 5°C), in a randomized crossover design, with trials separated by one week. Recovery of neuromuscular performance was assessed using 20 m maximal sprint, maximal countermovement-jump (CMJ), and isometric leg press tests, performed 14 hours after exercise. Heart rate (HR), heart rate variability (HRV), sleep diary, muscle soreness, and indirect muscle damage markers were measured pre and post exercise. The decrease in CMJ performance from pre- to post-exercise was attenuated after IRS compared to PAS (p < 0.01). The IRS session resulted in higher HR and lower root mean square of successive differences between normal heartbeats (RMSSD), and high and low frequency power, compared to PAS (p < 0.002). Post-exercise night-time HR and HRV did not differ following IRS vs. PAS. Muscle soreness was less severe, and perceived recovery was higher after IRS compared to PAS (p < 0.01). Post-exercise IRS attenuated the drop in explosive performance and decreased subjective muscle soreness after resistance training, which may enhance mood, readiness, and physical performance of an athlete. A single IRS session had no detrimental effects on recovery of the autonomic nervous system.

Injuries related to sauna bathing

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.

Detections of organophosphate and pyrethroid insecticide metabolites in urine and sweat obtained from women during infrared sauna and exercise: A pilot crossover study

Synthetic pesticides such as organophosphates and pyrethroids are commonly used worldwide yet the metabolic and long-term human health effects of these environmental exposures are unclear. Urinary detections of metabolites involving both classes of insecticides have been documented in various global populations. However, reports documenting similar detections in human sweat are sparse. In this study, the concentrations of four insecticide metabolites were measured using liquid chromatography coupled with tandem mass spectrometry in repeated sweat and urine collections (n = 85) from 10 women undergoing three interventions (control, infrared sauna and indoor bicycling) within a single-blinded randomised crossover trial. The Friedman test with post-hoc two-way analysis of variance, the related-samples Wilcoxon signed rank test and the Spearman's rank-order correlation test were used to analyse the results. Organophosphate metabolites were detected in 84.6% (22/26) and pyrethroids in 26.9% (7/26) of the collected sweat samples (pooled per individual, per intervention). Urinary concentrations of three of the four metabolites marginally increased after infrared sauna bathing: 3,5,6-trichloro-2-pyridinol (z = 2.395, p = 0.017); 3-phenoxybenzoic acid (z = 2.599, p = 0.009); and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (z = 2.090, p = 0.037). Urinary 3-phenoxybenzoic acid also increased after exercise (z = 2.073, p = 0.038) and demonstrated the most temporal variability (days to weeks) of any of the urinary metabolites. Definitive sweat/urine correlations were not demonstrated. These results indicate metabolites from organophosphate and pyrethroid pesticides can be detected in human sweat and this raises intriguing questions about perspiration and its role in the metabolism and excretion of synthetic pesticides.

Effect of water filtration infrared-A (wIRA) sauna on inorganic ions excreted through sweat from the human body

Sweat discharged as a result of exposure to sauna plays an important role in removing inorganic ions accumulated in the body, including heavy metals. In this study, inorganic ions (toxic and nutrient elements) excreted in the form of sweat from the body using a water-filtered infrared-A (wIRA) sauna were determined using inductively coupled plasma sector field mass spectrometry. The analyzed elements included eight toxic elements (Al, As, Be, Cd, Ni, Pb, Ti, and Hg) and 10 nutrient elements (Ca, Co, Cr, Cu, Fe, Mg, Mn, Se, V, and Zn), and their correlations were determined. Analysis of the sweat obtained from 22 people using the wIRA sauna showed a higher inorganic ion concentration than that obtained from conventional activities, such as exercise or the use of wet sauna, and the concentration of toxic elements in sweat was higher in females than in males. Correlation analysis of the ions revealed a correlation between the discharge of toxic elements, such as As, Be, Cd, and Ni, and discharge of Se and V, and Ni was only correlated with Mn. This study provides fundamental information on nutritional element supplementation when using wIRA sauna for detoxification.

Frequent sauna bathing offsets the increased risk of death due to low socioeconomic status: A prospective cohort study of middle-aged and older men

BACKGROUND AND AIM

Low socioeconomic status (SES) and frequent sauna bathing are associated with increased and decreased risk of all-cause mortality, respectively. Whether there is an interplay among SES, sauna bathing and all-cause mortality risk is not known. We aimed to evaluate the separate and joint associations of SES and frequency of sauna bathing (FSB) with all-cause mortality risk in a prospective cohort study.

METHODS

We employed the Kuopio Ischaemic Heart Disease Study cohort comprising of 2575 men aged 42-61 years at study entry. Self-reported SES and sauna bathing habits were assessed at baseline. Socioeconomic status was categorized as low and high (median cutoff) and FSB as low and high (defined as ≤2 and 3-7 sessions/week, respectively).

RESULTS

During a median follow-up of 27.8 years, 1618 deaths occurred. Comparing low vs high SES, the multivariable-adjusted HR (95 % CI) for all-cause mortality was 1.31 (1.18-1.45). Comparing high vs low FSB, the multivariable-adjusted HR (95 % CI) for all-cause mortality was 0.86 (0.76-0.97). Compared with high SES-low FSB, low SES-low FSB was associated with an increased risk of all-cause mortality 1.35 (1.20-1.51), without significant evidence of an association for low SES-high FSB and all-cause mortality risk 1.07 (0.89-1.29). Positive additive and multiplicative interactions were found between SES and FSB.

CONCLUSIONS

There exists an interplay among SES, sauna bathing and all-cause mortality risk in a general Finnish male population. Frequent sauna baths may offset the increased overall mortality risk due to low SES.

Inflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort study

Inflammation and sauna bathing are each related to the risk of all-cause mortality. The interplay between inflammation, sauna bathing and all-cause mortality is not well understood. We aimed to evaluate the separate and joint associations of inflammation (high sensitivity C-reactive protein, hsCRP) and frequency of sauna bathing (FSB) with all-cause mortality in a cohort of Caucasian men. We used the Kuopio Ischaemic Heart Disease Study cohort comprising 2575 men aged 42-61 years at baseline. Serum hsCRP was measured using an immunometric assay and sauna bathing habits were assessed by a self-administered questionnaire. High sensitivity CRP was categorized as normal and high (≤ 3 and > 3 mg/L, respectively) and FSB as low and high (defined as ≤ 2 and 3-7 sessions/week respectively). A total of 1618 deaths occurred during a median follow-up of 27.8 years. Comparing high vs normal hsCRP levels, the multivariable-adjusted HR (95% CI) for all-cause mortality was 1.27 (1.13-1.44). Comparing high vs low FSB, the multivariable-adjusted HR (95% CI) for all-cause mortality was 0.86 (0.76-0.97). Compared with normal hsCRP-low FSB, high hsCRP-low FSB was associated with an increased risk of all-cause mortality 1.28 (1.12-1.47), with no evidence of an association for high hsCRP-high FSB and all-cause mortality risk 1.06 (0.81-1.40). Positive additive and multiplicative interactions were found between hsCRP and FSB in relation to mortality. In a general Finnish male population, both hsCRP and FSB are each independently associated with all-cause mortality. However, frequent sauna baths appear to offset the increased all-cause mortality risk related to high hsCRP levels.

Sauna habits/bathing and changes in lower urinary tract symptoms - Tampere Ageing Male Urologic Study (TAMUS)

OBJECTIVE

To evaluate the effect of sauna bathing on lower urinary tract symptoms (LUTS) in a Finnish population-based cohort.

METHODS

A mail survey was sent to a population-based cohort of 50-, 60-, and 70-year-old men in 1994 followed by repeat questionnaires in 1999 and 2004. The evaluation of ten different types of LUTS was based on Danish Prostatic Symptom Score (DAN-PSS-1). The weekly frequency of sauna bathing was assessed in the first questionnaire and divided into three subgroups (0-1, 2, and ≥3). The prevalence, incidence, and remission rate of each LUTS was assessed based on the initial and follow-up assessments. In addition, the mean DAN-PSS-1 symptoms score, medication for LUTS, and operative treatment were determined at each time-point. Chi-square test, a linear-by-linear test, and binary logistic regression analysis were used to assess statistical significance.

RESULTS

The population-based cohort included initially 3,163, men of whom 1,306 (41.3%) responded to all three questionnaire rounds and were included in the analysis. There was no clear association between sauna bathing frequency and prevalence of the nine LUTS, nor with incidence and remission rates. The only exception was feelings of incomplete emptying, with lower prevalence associated with frequent sauna bathing. There were no clear differences in the medications or operations for LUTS by sauna bathing habits.

CONCLUSION

Based on our results, sauna bathing does not affect LUTS development or natural history in the long-term.

Death in the sauna-vitality markers for heat exposure

In sauna-associated deaths, the vitality of heat exposure is of great importance. Two case reports address this. First, we present the case of a 77-year-old man who was found dead in the sauna of his family home. When found, the sauna door was closed, and the sauna indicated a temperature of 78 °C. The body had already begun to decay and was partially mummified when it was found. In the other case, a 73-year-old woman was found dead in the sauna by her husband. In this case, the sauna door was also closed. The sauna was still in operation at a temperature of approximately 70 °C. Epidermal detachments were found. In both autopsies and their follow-up examinations, there were no indications of a cause of death competing with heat shock. The expression of heat shock proteins in kidneys and lungs and the expression of aquaporin 3 in skin were investigated to detect pre-mortal temperature influences.

Does sauna bathing protect against dementia?

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Frequent sauna bathing predicted decreased risk of dementia in a cohort from Finland.

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Result was independent of several dementia risk factors, and was not modified by sex.

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Findings support suggested benefits of sauna and passive body heating in the brain.

Repeated heat exposure like sauna bathing is suggested to beneficially affect against dementia development. The epidemiological evidence is, however, scarce. Therefore, we studied the association between heat exposure during sauna bathing (i.e., the frequency of sauna bathing, frequency of heat sessions, length of stay in heat, sauna temperature) and the subsequent risk of dementia. A prospective cohort study was conducted based on 13,994 men and women aged 30–69 and free from dementia diagnosis from the Finnish Mobile Clinic Follow-up Survey. During a follow-up of 39 years, a total of 1805 dementia patients were diagnosed. The sauna bathing data was gathered from a questionnaire. Analyses based on the Cox model included the sauna bathing variables and the potential confounding factors. Sauna bathing frequency was related to a reduced risk of dementia after adjustment for the potential sociodemographic, lifestyle, and metabolic risk factors of dementia considered. The hazard ratio of dementia between individuals sauna bathing 9–12 times per month in comparison with those not sauna bathing or sauna bathing less than four times per month was 0.47 (95% CI = 0.25–0.88) during the first 20 years of follow-up and 0.81 (95% CI = 0.69–0.97) during the whole follow-up. The results are in line with the hypothesis that sauna bathing provides protection against dementia. Further studies are required to verify the suggested benefits of sauna bathing.

Differences in cryostimulation and sauna effects on post-exercise changes in blood serum of athletes

OBJECTIVES

There is a growing body of evidence supporting the role of whole-body cryostimulation (WBC) and sauna - bathing as treatments for relaxation, mental well-being and several health problems. Despite their polar opposite temperatures, both of these treatments come with a dose of similar health benefits. This study is designed to compare effects of WBC and sauna application on the athletes' response to exercise.

DESIGN

The blood samples were collected from 10 professional cross-country skiers at four stages: before exercise, after exercise, at 1-h recovery and after 24 h of rest in sessions before and after 10 thermal treatments. Differential scanning calorimetry (DSC) was used to examine the process of serum denaturation. The parameters of endothermic transition were compared at various stages of each exercise session.

RESULTS

Post-exercise changes in DSC profiles of athlete's blood serum are similar in character but clearly stronger in the session held after sauna treatments and slightly weaker after WBC than those in the session not preceded by treatments. These changes can be, at least in part, explained by the exercise induced increase in the concentration of oxidized albumin. A return of serum denaturation transition to pre-exercise shape has been observed within a few hours of rest. It suggests relatively quick restoration of a fraction of non-oxidized albumin molecules during the recovery period.

CONCLUSIONS

An exercise performed by athletes after a series of sauna treatments leads to temporary greater modification of the blood serum proteome than the similar exercise during the session preceded by WBC treatments.

Repeated Dry Sauna Therapy Improves Quality of Life in Obese Korean People

Background

Dry sauna treatments improve the quality of life for chronic pain, congestive heart failure, and type 2 diabetes patients. This study aimed to determine whether dry sauna therapy improved the quality of life of obese people.

Methods

A total of 38 consecutive participants aged over 20 years with a body mass index of ≥25 kg/m² were recruited for the study. The participants were treated with a 90°C dry sauna for 15 minutes, twice daily for 4 consecutive days. To assess the quality of life, all participants completed the 5 level EQ-5D questionnaires and the EQ-Visual Analog Scale. Study parameters were measured on the same day prior to commencing the sauna sessions in a fasted state and 2 days after the last sauna session.

Results

The average age was 62.3±9.5 years; 84.2% of the participants were female. The mean body mass index was 28.5±2.4 kg/m². Dry sauna significantly improved the mean 5 level EQ-5D index scores from 0.83±0.12 to 0.89±0.11 and increased the mean EQ-Visual Analog Scale from 79.0±15.2 to 91.1±9.7. However, there were no significant changes in body mass index, blood pressure, heart rate, or body composition before and after the 8-session sauna therapy.

Conclusion

Dry sauna improved the health-related quality of life of obese patients without adverse events. Further clinical studies in larger study populations are needed to verify these findings and provide concrete evidence for obesity treatment.

Sex-on-premise venues, associated risk behaviors, and attitudes toward venue-based HIV testing among men who have sex with men in Lima, Perú

BACKGROUND

In Perú, HIV disproportionately affects men who have sex with men (MSM). Despite widespread access to treatment, the high rate of new HIV infections has remained unchanged over the last decade. Low knowledge of HIV status associated with late diagnosis is a key factor underlying the high HIV incidence observed in this setting, creating conditions for efficient onward transmission. Improving access to HIV testing and prevention services for those at highest risk is an important public health priority. Sex-on-premise venues (SOPVs) - saunas, sex clubs, pornographic movie theaters, hourly hotels, and bars/discos with areas where sex is permitted - may be opportune sites for outreach; however, further research on SOPVs and the populations who frequent them is needed to inform such efforts.

METHODS

We conducted a cross-sectional online survey of adult MSM in Lima, Perú to evaluate patterns of SOPV attendance, associated sexual risk behaviors, and attitudes toward SOPV-based interventions. Participants were recruited through outreach to social media networks affiliated with local LGBTQ-aligned community groups. Our primary analytic objective was to estimate the association of HIV-related sexual risk behaviors and SOPV attendance. Additionally, we performed exploratory analyses to describe risk behavior stratified by SOPV category and to examine the relationship between SOPV attendance and the use of online platforms to meet sex partners.

RESULTS

Overall, 389 MSM completed the survey from November 2018 through May 2019, of whom 68% reported attending an SOPV in the last 3 months. SOPV attendance was associated with multiple sexual risk behaviors, including transactional sex, group sex, substance use around the time of sex, and higher number of partners. Over two thirds of SOPV attendees indicated they would accept HIV testing if offered at SOPVs.

CONCLUSIONS

SOPV attendance was common among MSM in Lima who participated in our survey, and SOPV attendees reported significantly greater engagement in sexual risk behaviors related to HIV transmission. Attitudes toward hypothetical SOPV-based interventions were generally favorable. These findings suggest that outreach at SOPVs may be an effective mechanism for reaching a particularly high-risk sub-population of MSM in Perú to deliver targeted HIV testing and prevention interventions.

Infrared thermography: different options of thermal eyelid warming

PURPOSE

Current therapies of Meibomian gland dysfunction (MGD) include thermal eyelid warming. It was the aim of the study to investigate the temperature run after eyelid warming using 3 different techniques (hot compresses, Blephasteam® (Thea Pharma GmbH, France), and having a sauna) in patients with MGD compared with normal subjects by infrared thermography.

METHODS

A prospective case-control study was done. Temperature profiles of the eyelids were investigated in 93 subjects (49 normals, 44 MGD patients) after warming of the eyelids by 3 methods: hot compresses, Blephasteam®, and having a sauna. Temperature runs of the eyelids were measured with an infrared thermal imaging camera (VarioCAM® HD research 675/30 mm, InfraTec GmbH) at baseline and after eyelid warming for 10 min. Statistical analysis were done by Wilcoxon test or t tests for unpaired samples.

RESULTS

The initial eyelid temperature was significantly increased after the use of Blephasteam® compared with hot compresses in MGD and normal patients (p < 0.001). Having a sauna showed a similar warming effect of the eyelids than Blephasteam^® in normals and MGD patients (p > 0.05). Additionally, the warming effect of the eyelids after having a sauna was significantly longer than after the use of Blephasteam® in MGD (p = 0.016) and normal patients (p = 0.01).

CONCLUSION

Eyelid temperature after having a sauna was similar to commonly used warming devices; yet, the duration of the eyelid warming effect was longer. Thus, having a sauna might be an alternative option for warming of the eyelids.

Fatal α-PVP and amphetamine poisoning during a sauna and autoerotic practices

We describe the sudden death of a middle-aged man while having a sauna under the influence of α-pyrrolidinovalerophenone (α-PVP) (PM blood concentration: 0.8 mg/L), amphetamine (0.34 mg/L), and other drugs (buprenorphine, benzodiazepines), and engaging in solitary sexual activities. The drugs’ effects on the cardio-circulatory system and on body thermoregulation combined with the high temperatures are likely to have been central mechanisms leading to death. The high levels of adrenaline triggered by sexual arousal and the respiratory depression caused by buprenorphine, in association with benzodiazepines, may have also contributed to his death. This previously unreported type of accidental autoerotic death illustrates the risk of using amphetamine-like sympathomimetic drugs (e.g. cathinone derivates) in hot environments such as a sauna, and during sexual activities therein.

Acute and short-term efficacy of sauna treatment on cardiovascular function: A meta-analysis

OBJECTIVE

The role of sauna bathing in cardiovascular function treatment has been increasingly explored, but insufficient attention has been paid to its efficacy. We performed a meta-analysis to provide more evidence for the efficacy of sauna treatment in cardiovascular nursing.

METHODS

Sixteen peer-reviewed journal articles were screened to summarize the efficacy of the sauna on cardiovascular function. Both acute (0-30 min after the sauna) and short-term (2-4 weeks following the sauna treatment) efficacies were investigated.

RESULTS

For pooled acute efficacy, body temperature and heart rate significantly (p<0.001) grew by 0.94℃ and 17.86 beats/min, respectively; reductions of 5.55 mmHg (p<0.001) and 6.50 mmHg (p<0.001) were also observed in systolic blood pressure and diastole blood pressure, respectively. For combined short-term efficacy, left ventricular ejection fraction (LVEF), 6-min walk distance, and flow-mediated dilation (p<0.001) increased by 3.27%, 48.11 m, and 1.71%, respectively; greater amelioration in LVEF was observed in participants with lower LVEF. The proportion of patients with New York Heart Association class III and IV decreased by 10.9% and 12.2%, respectively. Systolic blood pressure, diastolic blood pressure, brain natriuretic peptide concentration, left ventricular end-diastolic dimension, cardiothoracic ratio, and left atrial dimension reduced by 5.26 mmHg (p<0.001), 4.14 mmHg (p<0.001), 116.66 pg/mL (p<0.001), 2.79 mm (p<0.001), 2.628% (p<0.05), and 1.88 mm (p<0.05), respectively, while the concentration of norepinephrine in the plasma remained unchanged.

CONCLUSION

Sauna treatment was found to play a positive role in improving cardiovascular function and physical activity levels, especially in patients with low cardiovascular function. These findings reveal that thermal intervention may be a promising means for cardiovascular nursing.

Sauna bathing, health, and quality of life among octogenarian men: the Helsinki Businessmen Study

BACKGROUND AND AIM

Sauna-type bathing has increased worldwide, and it has been related to both harmful and beneficial effects. There are few studies of bathing in sauna in very old age.

METHODS

The series consists of 524 mostly home-living survivors of the Helsinki Businessmen Study (HBS, mean age 86 years, range 80-95), who in 2015 responded to a questionnaire survey about lifestyle (including sauna bathing), prevalent diseases, and health-related quality of life (HRQoL, RAND-36).

RESULTS

Of the men 57.6% (n = 302) reported all-year round and 17.6% (n = 92) part-year sauna bathing. Sauna was currently used mostly once a week, but 10% bathed more than twice a week. Median time in the hot room was 15 min at 80 °C. Among 45.7% of the men, the habit had decreased with ageing, and 130 (24.8%) did not attend sauna. However, 92.2% of the latter had discontinued an earlier habit, respective proportions 20.7% and 75.0% among all-year and part-year users. Overall, reasons for decreased sauna bathing were nonspecific or related to mobility problems or diverse health reasons (n = 63). The most frequent motivations for sauna were relaxation and hygienic reasons. Of the RAND-36 domains physical function, vitality, social functioning, and general health were significantly better among sauna users than non-users. These differences partly remained after adjusting for prevalent diseases and mobility-disability.

CONCLUSIONS

Regular sauna bathing was common among octogenarian men and was associated with better HRQoL. However, reverse causality must be taken into account in this cross-sectional study. The bathing habit seemed to be prudent and had decreased in almost half of the cohort.

Sauna Bathing and Risk of Psychotic Disorders: A Prospective Cohort Study

OBJECTIVE

Sauna bathing has been suggested to promote mental well-being and relaxation, but the evidence is uncertain with respect to mental disorders. We aimed to assess the association of frequency of sauna bathing with risk of psychosis in the Kuopio Ischemic Heart Disease prospective population-based study.

SUBJECTS AND METHODS

Baseline sauna bathing habits were assessed in 2,138 men aged 42-61 years who had no history of psychotic disorders. Participants were classified into three groups based on the frequency of sauna bathing (once, 2-3, and 4-7 times per week).

RESULTS

During a median follow-up of 24.9 years, 203 psychotic disorders were recorded. A total of 537, 1,417, and 184 participants reported having a sauna bath once a week, 2-3 times, and 4-7 times per week, respectively. In Cox regression analysis adjusted for age, compared to men who had 1 sauna session per week, the hazard ratio (95% confidence intervals) of psychosis for 4-7 sauna sessions per week was 0.23 (0.09-0.58). In a multivariable model adjusted for several risk factors and other potential confounders, the corresponding hazard ratio was 0.21 (0.08-0.52). The association was similar after further adjustment for total energy intake, socioeconomic status, physical activity, and C-reactive protein (0.22 [0.09-0.54]) and was unchanged on additional adjustment for duration of a sauna session and temperature of the sauna bath (0.23 [0.09-0.57]).

CONCLUSION

Our study suggests a strong inverse and independent association between frequent sauna bathing and the future risk of psychotic disorders in a general male population.

Rehabilitation training in artificially heated environment

Sauna has become a popular club house facility where the dweller enjoys relaxation. Some exercise groups like yoga and Qigong practitioners, are making use of the heated environment to achieve quicker and better results of trainings. Sauna therapy is producing a thermal stress through hyperthermia. The cardiovascular system readily responds by increasing the heart rate which can become double the resting stage within minutes and cardiac output may have a 70% increase. The body's surface response to heat leads to a 40% of decrease in peripheral vascular resistance, thus allowing rapid peripheral blood flow which is responsible for greater heat dispersal directly from the skin. The chained physiological reactions of increased cardiac and pulmonary outputs, while blood pressure drops suggest that Sauna could be good for chronic diseases. When active stretching are executed simultaneously with controlled breathing in a smooth synchronized chain of activities under the individual's free will, a harmonized state of mind reaching the level of meditation follows. Sauna room environment initiates a physiological stat equivalent to moderate exercises. Qigong practice is typical anaerobic training. Both Sauna and Qigong lead to a tranquility of the mind. The unique nature of practicing Qigong in a heated environment is therefore clear. A small pilot study on Qigong practice within the Sauna room showed a higher increase in heart rate which amounted to 30%-40% above the pre-exercise level. The blood pressure checked after Qigong, on the contrary, remained stable or even slightly decreased.

Sauna bathing reduces the risk of respiratory diseases: a long-term prospective cohort study

Sauna bathing has been linked with numerous health benefits. Sauna bathing may reduce the risk of respiratory diseases; however, no prospective evidence exists to support this hypothesis. We aimed to assess the association of frequency of sauna bathing with risk of respiratory diseases (defined as chronic obstructive pulmonary disease, asthma, or pneumonia). Baseline sauna bathing habits were assessed in a prospective cohort of 1935 Caucasian men aged 42-61 years. During a median follow-up of 25.6 years, 379 hospital diagnosed incident cases of respiratory diseases were recorded. In adjustment for several major risk factors for respiratory conditions and other potential confounders, the hazard ratios (HRs) 95% confidence intervals (CIs) of respiratory diseases were 0.73 (0.58-0.92) and 0.59 (0.37-0.94) for participants who had 2-3 and ≥4 sauna sessions per week respectively compared with participants who had ≤1 sauna session per week. The multivariate adjusted HR (95% CI) for pneumonia was 0.72 (0.57-0.90) and 0.63 (0.39-1.00) for participants who had 2-3 and ≥4 sauna sessions per week respectively. Frequent sauna baths may be associated with a reduced risk of acute and chronic respiratory conditions in a middle-aged male Caucasian population.

Effects of far-infrared sauna bathing on recovery from strength and endurance training sessions in men

Purpose

This study investigated effects of far-infrared sauna (FIRS) bathing on recovery from strength training and endurance training sessions, but also possible differences between FIRS and traditional (TRAD) Finnish sauna bathing.

Methods

Ten healthy physically active male volunteers had on various days either a 60 min hypertrophic strength training session (STS) or a 34–40 min maximal endurance training session (ETS), which was following by 30 min bathing in special FIRS sauna at temperature of 35–50°C and humidity of 25–35%. After the sauna, subjects sat for 30 min at room temperature (21°C and 25–30% humidity). In comparison, 30 min of TRAD took place at 35–50°C and in 60–70% humidity. Performance tests included maximal isometric bench press and leg press, counter movement jump (CMJ) and maximal oxygen uptake on a treadmill.

Results

After STS, there were decreases in maximal isometric bench press (p < 0.001), maximal isometric leg press (p < 0.001), CMJ (p < 0.001) and pH (p < 0.001), but increases in heart rate (p < 0.001) and lactate concentration (p < 0.001) as expected. During recovery there were no differences in any variables between FIRS and no sauna bathing (NO SAUNA). Maximal ETS increased oxygen uptake (p < 0.001), heart rate (p < 0.001), lactate concentration (p < 0.001) and decreased pH (p < 0.001) as expected. During recovery at 30 min, CMJ was significantly (p < 0.05) higher (0.34 ± 0.09 m) after FIRS bathing than after sitting with NO SAUNA (0.32 ± 0.0 m). After sauna heart rate was higher (p < 0.05) in TRAD (92 ± 13 beats/min) than in FIRS (71 ± 7 beats/min).

Conclusion

In conclusion, deep penetration of infrared heat (approximately 3–4 cm into fat tissue and neuromuscular system) with mild temperature (35–50°C), and light humidity (25–35%) during FIRS bathing appears favorable for the neuromuscular system to recover from maximal endurance performance. FIRS bathing is a very light loading for the body and provides a comfortable and relaxing experience.

Different Physiological and Subjective Responses to the Hyperthermia Between Young and Older Adults: Basic Study for Thermal Therapy in Cardiovascular Diseases

BACKGROUND

Thermal therapy has been used as adjuvant therapy in patients with cardiovascular disease. However, little is known about responses to thermal stress in older adults. We examined the effects of thermal stress in younger and older healthy Japanese individuals.

METHODS

The study included 12 young (mean age, 22 years) and 12 older (mean age, 68 years) healthy adults and was performed under strict temperature and humidity control to minimize confounding. Participants lay supine throughout three consecutive 30-minute phases: Phase I (heating at 70°C in a dome-shaped sauna), Phase II (insulation in the sauna), and Phase III (cool down). Physiological parameters and subjective thermal sensations were compared within and between two age groups.

RESULTS

Mean skin temperature increased significantly in both age groups (Phase I) and after the first 10 minutes was higher among older adults (by 6.8°C vs 6.0°C among younger; p < .01). Mean rectal temperature increased by 0.6°C in both groups (Phase II). Mean heart rate increased significantly in both age groups (Phase II) and was higher among younger adults (by 21.4 vs 11.3 beats/min among older adults; p < .05). Both systolic (by 15.1 mmHg) and diastolic (by 10.5 mmHg) blood pressure dropped significantly among older adults (Phase I), returning to baseline in Phase III; no changes were noted among those younger. There was no between-group difference in fluid loss or thermal sensations.

CONCLUSIONS

Compared with younger adults, older adults are more likely to drop blood pressure in response to thermal stress but had similar fluid loss and subjective responses.