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Non-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trials

SR/MA of 20 RCTs (2–15 weeks; saunas, hot baths, hot yoga, local heating) found largely null pooled effects on flow-mediated dilation, arterial stiffness, lipids, glycaemia, CRP, and HRV; overall systolic BP change was non-significant (−2.46 mmHg) but subgroup analyses suggested significant reductions with whole-body heating (−4.11 mmHg) and in adults with coronary risk/CVD (−2.52 mmHg).

Design

  • Corpus: 20 RCTs (Nov 2024 search); 2–15 weeks; modalities include hot water immersion, Finnish sauna, hot yoga, local heating
  • Population: adults
  • Endpoint family: cardiometabolic + vascular surrogates (FMD, PWV, lipids, HbA1c, CRP, HR, HRV, etc.)

Mostly null pooled signals (abstract)

Authors report no significant pooled effects for FMD, PWV, resting HR, HRV, fasting glucose, HbA1c, total/HDL/LDL cholesterol, triglycerides, and CRP.

Blood-pressure nuances

  • Overall SBP: −2.46 mmHg (95% CI −5.02 to 0.10) — not significant (I² ≈ 60%)
  • Subgroup — systemic (whole-body) heating: −4.11 mmHg (−7.36 to −0.86)
  • Subgroup — adults with coronary risk / established CVD: −2.52 mmHg (−4.26 to −0.79)

Evidence hygiene

Surrogate endpoints predominate—pair with Kuopio-style long-term mortality observational rows on sauna without treating this MA as outcome-equivalent.

Publication

Hamaya R, Christensen RH, Bangshaw NS, et al. Sports Med. 2025 Aug 17. Online ahead of print. PMID 41049507.

Outcomes

  • Systolic Blood Pressure
    -2.46
    mmHg (Millimetres of Mercury)
  • Systolic Blood Pressure
    -4.11
    mmHg (Millimetres of Mercury)
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