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Cold water immersion, heart rate variability and post-exercise recovery: systematic review
PRISMA-style systematic review of 12 athlete RCTs: every included trial reported parasympathetic-flavored HRV reactivation after CWI versus baseline; six showed statistically significant gains versus passive recovery and eight described moderate-to-large effects—review-level synthesis, not a new pooled meta-analytic effect size.
Why this matters
Indexes post-exercise cold-water immersion (CWI) specifically through autonomic recovery lenses (HRV), complementing DOMS/CK network meta-analyses (wang-2025-cwi-dose-network-meta, bleakley-2023-cold-immersion) on cold-plunge.
Methods (abstract-level)
- Design: systematic review of randomised clinical trials
- Question: CWI effects on post-exercise recovery operationalised with HRV endpoints in athletes
- Corpus: 12 RCTs retained after database search (Scopus, Web of Science, MEDLINE) and bias appraisal (Cochrane-style framework per authors)
Results reported by authors
- Directional signal: all 12 studies described parasympathetic reactivation patterns with CWI after exertion (heterogeneous metrics/timings across trials).
- Significance vs passive recovery: 6 / 12 trials reported p < 0.05 HRV differences favouring CWI versus passive recovery in the authors’ tabulation.
- Effect-size language: 8 / 12 trials were described as showing moderate-to-large effect sizes on HRV-oriented readouts (authors’ qualitative synthesis; metrics differ across instruments).
Evidence hygiene
- Not a replacement for pragmatic cold-shower workplace trials (
buijze-2016-cold-shower-health-workoncold-exposure)—temperature, immersion depth, and timing versus exercise differ materially. - Athlete-only inclusion may overstate transfer to sedentary beginners; combine with individual wearable n=1 logs already linked for expectation calibration.
Publication
Gálvez-Rodriguez C, Valenzuela-Reyes P, Fuentealba-Sepúlveda S, Farias-Valenzuela C, Salinas AE. Physiother Res Int. 2025 Apr;30(2):e70033. PMID 39918163; DOI 10.1002/pri.70033.
Outcomes
- Heart Rate VariabilitySystematic review of 12 athlete RCTs: all reported parasympathetic-leaning HRV reactivation after CWI post-exercise; 6/12 statistically significant vs passive recovery (p<0.05); 8/12 moderate-to-large effect sizes per authors' qualitative synthesis (metrics heterogeneous).
- otherConclusion (authors): acute post-exercise CWI may positively support parasympathetic reactivation as measured by HRV—narrative/systematic review tier; not a single pooled SMD across instruments.