Sauna and HFpEF: What the 2026 Pilot Trial Shows
Key insights
- A 2026 single-arm pilot of 18 stable HFpEF outpatients found that twice-weekly sessions in a 60°C sauna for 10 weeks were feasible and safe, with no adverse events reported and 97% adherence 1.
- Peak oxygen uptake rose from 18.2 to 20.6 ml/min/kg and six-minute walk distance from 494 to 527 m, alongside lower resting blood pressure and heart rate 1.
- There was no control group, so expectation, learning effects and regression to the mean cannot be separated from a true sauna effect; the authors say a larger randomised trial is planned 1.
- The gains partly faded three months after sessions stopped, which suggests any benefit depends on continued use 1.
- Anyone with heart failure should treat this as early evidence, not advice, and speak to their cardiology team before using heat.
Heart failure with preserved ejection fraction (HFpEF) is the form of heart failure in which the left ventricle still ejects a normal fraction of blood but fills poorly because the muscle is stiff. It is common in older adults, often alongside high blood pressure, obesity and diabetes, and it is notoriously hard to treat: exercise intolerance is the defining symptom, and options that improve it are limited.
Sauna bathing has long attracted interest in cardiology. Finnish cohort data link frequent sauna use with lower cardiovascular mortality 2, and small trials of mild heat therapy in heart failure have reported short-term improvements in cardiac markers 3. Until recently, though, little of this had been tested specifically in HFpEF.
In 2026, the SAUNA-HFpEF pilot study, published in the European Journal of Heart Failure, offered a first look. Here is what it did, what it found, and how far those findings can be pushed.
How the SAUNA-HFpEF pilot worked
The investigators enrolled clinically stable HFpEF outpatients, 18 of whom completed the study (mean age 68, 61% women, mean BMI about 31). Participants attended supervised sessions in a 60°C sauna twice weekly for 10 weeks, building from 8 to 15 minutes per session. Blood pressure and heart rate were measured before, immediately after and 20 minutes after each session 1.
The primary aim was exploratory: feasibility, safety and tolerability. Secondary measures included exercise testing, echocardiography, muscle strength and quality-of-life questionnaires, and the team also took skeletal muscle biopsies to look at gene expression 1. It was a single-arm, single-centre study with no comparison group.
What the data showed
Safety and adherence were reassuring: no adverse events were reported and adherence averaged 97%. Peak VO₂ rose from 18.2 to 20.6 ml/min/kg (P < .001), the anaerobic threshold from 10.6 to 12.9 ml/min/kg, and six-minute walk distance from 494 to 527 m 1.
Resting systolic blood pressure fell from about 132 to 122 mmHg, diastolic from 82 to 77 mmHg, and resting heart rate from 77.5 to 70.5 bpm. A marker of diastolic filling pressure on echocardiography (E/e') improved from 10.0 to 8.3, and quadriceps strength rose modestly. Muscle biopsies showed lower expression of several catabolic genes and higher expression of anabolic pathways 1.
Why the result needs careful reading
With 18 people and no control arm, this cannot show that the sauna caused the changes. Participants knew they were being treated, were closely supervised for ten weeks, and may have become more active or more confident in exercise testing. Exercise capacity in a frail, older population is also sensitive to familiarisation with the test itself. The authors acknowledge these limits and note that a larger multicentre randomised trial is planned 1.
The follow-up is informative in a different way. Three months after sessions ended, peak VO₂ and anaerobic threshold had declined from their end-of-study values 1. If the improvements were purely a testing artefact, you might not expect them to track exposure so closely; if they were real, they appear to need maintenance, much like fitness.
How this fits the wider evidence
The broader picture is consistent but mostly indirect. In the Kuopio cohort of 2,315 Finnish men followed for a median of 20.7 years, those who bathed four to seven times a week had about 50% lower cardiovascular mortality and 40% lower all-cause mortality than those bathing once a week 2. That is observational data in a largely healthy male population, so it cannot be applied directly to people with heart failure.
A 2018 systematic review of sauna in heart failure found that short courses of infrared sauna (60°C for 15 minutes, five days a week for two to four weeks) were associated with lower BNP and improved ejection fraction, but the authors called for longer-term studies 3. We have covered that literature in more depth in our piece on sauna and heart failure.
Practical guidance
The pilot used a modest 60°C, short sessions, a gradual build-up and supervision with blood pressure monitoring. That is very different from a 90°C session taken unsupervised. People with heart failure often take diuretics, blood pressure medication or other drugs that change how they handle heat and fluid loss, and low blood pressure after a session is a real consideration. Anyone with HFpEF should discuss heat exposure with their cardiology team first, and any start should be gradual, seated, well hydrated and stopped at the first sign of dizziness, breathlessness or chest discomfort.
The Contrast Market Perspective
The most useful detail in this study may be its protocol: a low, controlled temperature, timed sessions and a gradual progression. Reproducing that at home depends on a heater and controls that hold a set temperature accurately and a thermometer you can trust. If you are weighing a sauna for a specific health goal, we are happy to talk it through: Schedule a consultation.
References
1. Bekfani et al., SAUNA-HFpEF pilot study (2026). 2. Laukkanen et al., Kuopio cohort (2015). 3. Källström et al., systematic review and meta-analysis (2018).
Footnotes
- Bekfani T, Abo Hwach A, Moebert R, et al. (2026). Effects of sauna bathing on exercise capacity and muscle function in HFpEF. European Journal of Heart Failure. PubMed ↩︎
- Laukkanen T, Khan H, Zaccardi F, Laukkanen JA (2015). Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine. Summary ↩︎
- Källström M, Soveri I, Oldgren J, et al. (2018). Effects of sauna bath on heart failure: a systematic review and meta-analysis. Clinical Cardiology. DOI ↩︎