Finnish sauna and heart patients: a trial that found no change
People with stable heart disease used a Finnish sauna four times a week for eight weeks. Their bodies adapted to the heat, but blood vessels and blood pressure did not change.
The short version
Researchers randomly assigned 41 adults with stable coronary artery disease to eight weeks of Finnish sauna, four sessions a week at about 79°C, or to carry on as usual. The sauna group adapted to the heat: they sweated more and their resting body temperature dropped slightly. But the measures the trial was designed to test did not change: how well arteries widen, artery stiffness and blood pressure. It is a small trial, in people already treated for heart disease, and it tested eight weeks, not years.
Keep in mind
A small trial in people already treated for heart disease. No change in eight weeks does not settle what sauna does over years.
What they found
The sauna group showed heat adaptation: resting core temperature was 0.27°C lower and they sweated 0.3 liters an hour more in the sauna.
Artery widening did not change differently between the groups (control +0.07 points, sauna +0.15 points). Artery stiffness, systolic and diastolic blood pressure did not differ either.
Blood flow in the small vessels changed differently between the groups, but because it fell slightly after sauna and rose in the control group, not because sauna improved it.
What this means for your practice
If you have heart disease, this trial does not show that sauna improves your blood vessels or blood pressure. Ask your doctor before starting regular sauna.
This does not establish a sauna routine to follow.
Methods and limitations
What the researchers did
The researchers recruited 41 adults with stable coronary artery disease, on average 62 years old, and randomly assigned them to Finnish sauna or to carry on with their usual lifestyle.
The sauna group went four times a week for eight weeks, 20 to 30 minutes a time, at about 79°C with dry air. They used the sauna on their own, without supervision.
Before and after, the researchers measured how well the arm artery widens (flow-mediated dilation), artery stiffness, blood flow in the small vessels of the forearm, and blood pressure.
How much can this tell us?
This is a well-designed test of a real Finnish sauna, used much as people use one at home. That makes a result of no change worth taking seriously.
It is small, and the people in it were already on treatment for heart disease, which may leave less room for improvement. Most were men.
Eight weeks is short. The trial does not speak to the long-term links seen in the Finnish observation studies. It does show that the vessel changes seen in some hot-water trials do not appear reliably with sauna.
What makes it useful
- Randomized, with a control group
- A real Finnish sauna at a normal temperature
- Several direct measures of vessel health
What limits it
- Small: 41 people
- People already treated for heart disease
- Mostly men
- Eight weeks, not years
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular heat keeps blood vessels healthy. Not supported
Low certaintyNo effect foundBody signals
A few weeks of regular heat lowers blood pressure. Some support
Low certaintySmall effectBody signals
Read the original
Debray A, Gravel H, Garceau L, Bartlett AA, Chaseling GK, Barry H, Behzadi P, Ravanelli N, Iglesies-Grau J, Nigam A, Juneau M, Gagnon D. Finnish sauna bathing and vascular health of adults with coronary artery disease: a randomized controlled trial. J Appl Physiol (1985). 2023;135(4):795-804.
DOI 10.1152/japplphysiol.00322.2023 · PubMed 37650138