Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 28972808 · doi:10.1080/07853890.2017.1387927
What was done
A prospective cohort study assessed baseline cardiorespiratory fitness (CRF, measured via respiratory gas analysis) and frequency of sauna bathing (FSB) in 2,277 men. CRF was categorized as low or high by median split, and FSB was categorized as low (≤2 sessions/week) or high (3-7 sessions/week). Participants were followed for a median of 26.1 years to track cardiovascular and all-cause mortality.
What was found
During follow-up, 520 cardiovascular deaths and 1,124 all-cause deaths occurred. Comparing high versus low CRF, multivariate-adjusted hazard ratios (HRs) were 0.51 (95% CI, 0.41-0.63) for cardiovascular mortality and 0.65 (95% CI, 0.57-0.75) for all-cause mortality. For high versus low FSB, HRs were 0.74 (95% CI, 0.59-0.94) for cardiovascular mortality and 0.84 (95% CI, 0.72-0.97) for all-cause mortality. Compared with the low CRF & low FSB reference group, HRs for cardiovascular mortality were 0.42 (95% CI, 0.28-0.62) for high CRF & high FSB, 0.50 (95% CI, 0.39-0.63) for high CRF & low FSB, and 0.72 (95% CI, 0.54-0.97) for low CRF & high FSB. Corresponding HRs for all-cause mortality were 0.60 (95% CI, 0.48-0.76), 0.63 (95% CI, 0.54-0.74), and 0.78 (95% CI, 0.64-0.96).
Why it matters
Frequent sauna bathing and cardiorespiratory fitness show additive associations with reduced mortality risk, suggesting separate and complementary pathways of cardiovascular protection.
Limits
The cohort included only men, limiting generalizability to women. Sauna use and fitness were measured only at baseline without accounting for changes over the 26.1-year median follow-up. As an observational study, residual confounding from socioeconomic status or overall healthy behaviors cannot be ruled out.
Cited by
- supports Observational data from Finland shows that combining regular exercise with sauna bathing is associated with a greater life expectancy than regular exercise alone.