Cold-Water Immersion for Post-exercise Recovery: An Overlap-Aware Umbrella Review.

BACKGROUND

Cold-water immersion (CWI) is widely used after strenuous exercise, but review-level findings vary by outcome, comparator, recovery window, population, and protocol. Reuse of the same primary studies across reviews can also exaggerate apparent consistency.

METHODS

We searched PubMed, Web of Science, SPORTDiscus, Cochrane Library, Embase, and Scopus from inception to 30 January 2026 for systematic reviews, meta-analyses, and network meta-analyses of post-exercise CWI. Fourteen reviews were included. Primary-study overlap was quantified using the corrected covered area (CCA) overall and for outcome-specific study-to-review mappings. Because overlap was high and review-level estimates were statistically dependent, we did not perform second-order meta-analysis. Source-verified estimates were synthesized in a structured, overlap-aware format. Methodological quality was assessed with AMSTAR 2.

RESULTS

Of the 14 included reviews, 13 provided quantitative estimates, whereas one review provided narrative evidence on heart rate variability (HRV). Overall CCA was 12.68% (high); 99 of 165 primary-study families appeared in at least two reviews. Outcome-specific CCA was 15.03% for delayed onset muscle soreness (DOMS; very high) and ranged from 0.00% for interleukin-6 (IL-6) to 25.00% for C-reactive protein (CRP). It was not calculable for HRV, because one review contributed. AMSTAR 2 confidence was low in 2 reviews and critically low in 12. DOMS showed the most consistent favorable pattern: source-review standardized mean differences ranged from -1.04 to -0.37, although the largest estimate was soccer-specific and its 95% prediction interval crossed zero. Because DOMS evidence was highly redundant across the contributing reviews, this apparent consistency does not represent independent replications. Findings for objective performance and biochemical outcomes were inconsistent, time-dependent, or comparator-dependent.

CONCLUSIONS

Within the available review-level evidence, CWI was associated with the most consistent reduction in self-reported short-term post-exercise DOMS, but the clinical importance of the observed effects remains uncertain. Evidence does not support a uniform benefit across objective performance or inflammatory outcomes. Protocol observations, including commonly studied temperatures and durations, are descriptive and should not be interpreted as an optimized prescription. Trial Registration PROSPERO CRD420261332482.