Key Takeaway
Meta-analysis of 16 studies found sauna acutely lowers blood pressure by 5-6 mmHg and over 2-4 weeks improves ejection fraction, walking distance, and vascular function in cardiovascular patients.
Summary
This meta-analysis pooled data from 16 peer-reviewed studies to quantify both the acute (within 30 minutes) and short-term (2-4 weeks) effects of sauna treatment on cardiovascular function. It provides the most comprehensive pooled analysis of sauna's cardiovascular effects to date.
For acute effects, sauna increased core body temperature by 0.94 degrees C and heart rate by approximately 18 beats per minute, while significantly reducing systolic blood pressure by 5.55 mmHg and diastolic blood pressure by 6.50 mmHg. These immediate hemodynamic changes mirror the responses seen during moderate-intensity aerobic exercise.
For short-term effects over 2-4 weeks of regular use, the analysis found clinically meaningful improvements across multiple cardiovascular markers: left ventricular ejection fraction increased by 3.27%, six-minute walk distance improved by 48 meters, and flow-mediated dilation (a measure of endothelial function) improved by 1.71%. Cardiac biomarkers including brain natriuretic peptide and left ventricular dimensions also improved. These findings support sauna as a legitimate adjunct therapy for cardiovascular health, particularly in patients with reduced cardiac function.
Methods
- Systematic review and meta-analysis of 16 peer-reviewed studies
- Searched PubMed, EMBASE, CINAHL, Cochrane Library, and CNKI databases
- Included studies examining sauna effects on cardiovascular function
- Separated analysis into acute effects (0-30 min post-sauna) and short-term effects (2-4 weeks)
- Outcomes included blood pressure, heart rate, body temperature, LVEF, 6-minute walk distance, flow-mediated dilation, and cardiac biomarkers
- Random-effects model used for meta-analysis
Key Results
- Acute effects (within 30 min of sauna):
- Body temperature: +0.94 degrees C (p<0.001)
- Heart rate: +17.86 bpm (p<0.001)
- Systolic blood pressure: -5.55 mmHg (p<0.001)
- Diastolic blood pressure: -6.50 mmHg (p<0.001)
- Short-term effects (2-4 weeks):
- Left ventricular ejection fraction: +3.27% (p<0.001)
- 6-minute walk distance: +48.11 meters (p<0.001)
- Flow-mediated dilation: +1.71% (p<0.001)
- Improvements in BNP and left ventricular dimensions
- NYHA heart failure classification improved
Limitations
- Heterogeneity in sauna protocols across included studies (traditional vs infrared, varying temperatures and durations)
- Most studies had relatively small sample sizes
- Short-term follow-up periods (2-4 weeks maximum)
- Limited long-term outcome data
- Many included studies focused on heart failure patients, limiting generalizability to healthy populations
- Publication bias possible given positive-result tendency in included studies