Passive heating lowered blood pressure a little across 51 studies and left heat shock proteins and CRP unchanged
This 2025 Experimental Physiology meta-analysis pooled controlled studies of people heated without exercise. It looked at single sessions and repeated sessions separately.
The paper
Heat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysis
Price BS, Lucas SJE, Akerman AP, Gilworth RE, et al.. Experimental Physiology, 2025:EP092404.
See the study at a glance
- Design
- Systematic review and meta-analysis
- People
- Participants of 51 controlled studies
- Who they were
- People in controlled studies of passive heating without exercise. The search ran to January 2025.
- What they did
- Any kind of passive heating without exercise. The analysis treated single sessions and repeated sessions separately and dropped outlying studies before the final estimates.
- How long
- Single sessions and repeated programs
These numbers came out of it
−5 mmHg
Systolic blood pressure (the top number) fell 5 mmHg after repeated heating across 8 studies. The plausible range (95% confidence interval) ran from −9 to −1.
−2 mmHg
Diastolic pressure (the bottom number) fell 2 mmHg after single sessions across 20 studies. Across 9 studies of repeated sessions it fell 3 mmHg.
No change
Heat shock proteins stayed the same after single or repeated heating.
No change
The inflammation marker C-reactive protein (CRP) held steady after single or repeated heating. Arterial stiffness didn't change either.
The researchers did this
Researchers searched the literature to January 2025 and pooled 51 controlled studies in which people were heated without exercising. They analyzed single sessions and repeated sessions separately and removed outlying studies before the final estimates.Source 1 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗
Blood pressure came down a few points. Across 8 studies of repeated sessions, systolic pressure fell 5 mmHg, and the plausible range ran from −9 to −1. Single sessions took 2 mmHg off diastolic pressure across 20 studies. They also lowered mean arterial pressure (the average pressure over a whole heartbeat) by 5 mmHg across 22 studies.
Heat shock proteins didn't change after single or repeated heating. C-reactive protein and arterial stiffness stayed flat as well. Arteries widened better in a flow-mediated dilation test after single sessions, and the improvement didn't show up after repeated ones.
The study can't tell you these things
- The abstract gives no pooled participant count and doesn't split results by type of heat, so you can't pick out what saunas alone did.
- The final estimates came after outlying studies were removed. Different choices about outliers could shift the pooled numbers.
- The review covered blood markers and blood pressure. It didn't look at heart attacks or deaths.
- A separate review limited to randomized trials found no significant change in systolic pressure or CRP.Source 2 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗
We cited these sources
- 01Price BS, Lucas SJE, Akerman AP, Gilworth RE, Lucas RAI. Heat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysis. Experimental Physiology. 2025:EP092404. doi:10.1113/EP092404 PMID 41166412
- 02Hamaya R, Joyama Y, Miyata T, Fuse SI, Yamane N, Maruyama N, et al.. Non-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trials. American Journal of Preventive Cardiology. 2025;23:101082. doi:10.1016/j.ajpc.2025.101082 PMID 41049507