Effects of cold-water immersion at different body regions on post-exercise muscle damage recovery: a systematic review and meta-analysis.

This was a systematic review and meta-analysis of 30 randomised controlled trials (RCTs) comparing a single session of cold-water immersion (CWI) against passive rest (sitting quietly) after exercise that caused muscle damage.

**The intervention:** Cold-water immersion, defined as sitting or standing in water between 10–15°C for 11–15 minutes (the standard "dosage" range identified in prior research). The authors categorised CWI into two types based on anatomical landmarks:

**Whole-body immersion:** Water level above the iliac crest (hip bone) — meaning up to the navel, sternum, or neck.

**Partial immersion:** Water level at or below the iliac crest — typically just the legs and hips.

**The comparator:** Seated passive rest (no cold exposure, no active recovery).

**The outcome measures (four key indicators):**

1. **Maximal voluntary isometric contraction (MVIC):** A measure of maximum strength — how hard you can push against an immovable object.

2. **Countermovement jump (CMJ):** A measure of explosive power — how high you can jump from a standing start with a quick dip-and-jump motion.

3. **Serum creatine kinase (CK):** A blood marker of muscle cell damage — higher levels mean more muscle breakdown.

4. **Delayed onset muscle soreness (DOMS):** Subjective pain felt 24–72 hours after exercise, measured using a Visual Analog Scale (VAS, 0–10 or 0–100 mm scale).

The authors also looked at how these outcomes changed over time, measuring them immediately after CWI (0 hours) and at 24, 48, and 72 hours post-exercise.

The meta-analysis pooled data from 30 RCTs involving a total of approximately 600 participants (exact total N not reported in the abstract, but individual study sample sizes ranged from 10 to 58 participants). The populations were:

**Mostly healthy young men** (aged 16–37 years, with most studies in the 20–25 range)

**Athletes and active individuals:** Soccer players, rugby players, basketball players, jiu-jitsu athletes, runners, team sport athletes, and healthy physically active males

**Very few women:** Only 4 of 30 studies included female participants (Doeringer 2017: 8F/4M; Heinke 2024: 3F/8M; Rupp 2012: 9F/13M; Silva 2017: 2F/10M)

**All participants were healthy** with no reported injuries or medical conditions that would affect recovery

**Setting:** Laboratory-based exercise protocols designed to induce muscle damage (eccentric exercise, plyometrics, sport-specific drills, or resistance training).

**Key limitation for generalisability:** Nearly all participants were young, healthy, physically active males. Results may not apply to older adults, sedentary individuals, people with chronic conditions, or women (who have different hormonal and physiological responses to cold exposure and muscle damage).

The authors extracted data from each included study using standardised forms. The specific instruments and scales used across the 30 studies included:

**MVIC (maximal strength):** Isokinetic dynamometer or strain gauge — participants pushed maximally against a fixed resistance for 3–5 seconds. Measured in Newtons or Newton-metres.

**CMJ (explosive power):** Force plate or contact mat measuring jump height (cm) or peak power (Watts). Participants performed a countermovement jump — dipping to ~90° knee angle then jumping as high as possible.

**CK (muscle damage marker):** Blood draw from antecubital vein, analysed via spectrophotometry or enzymatic assay. Reported in U/L (units per litre).

**DOMS (subjective soreness):** Visual Analog Scale (VAS) — a 100 mm line where 0 = no pain and 100 = worst imaginable pain, or a 0–10 numerical rating scale. Participants rated soreness during a standardised movement (e.g., squatting or palpation of the muscle belly).

**Timing of measurements:** Baseline (pre-exercise), immediately post-CWI (0 hours), and at 24, 48, and 72 hours post-exercise.

**Study design:** This is a systematic review and meta-analysis — a study that statistically combines results from multiple independent RCTs. The authors followed PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, which is the gold standard for transparent reporting. The protocol was pre-registered on PROSPERO (registration number CRD420251171826), meaning the authors committed to their analysis plan before seeing the results — this reduces the risk of selective reporting.

**Search strategy:** Four major databases (PubMed, Embase, Web of Science, Cochrane Library) were searched from database inception to October 20, 2025. The authors also manually screened reference lists of included studies and relevant reviews. This is comprehensive but not exhaustive — they did not search grey literature or non-English databases.

**Inclusion criteria:**

Randomised controlled trials (RCTs) only — this is the strongest design for causal inference

Compared a single acute session of CWI (not repeated daily CWI) against passive rest

Measured at least one of the four outcomes (MVIC, CMJ, CK, DOMS)

Published in English

**Quality assessment:** Two independent reviewers assessed each study using:

**PEDro scale** (Physiotherapy Evidence Database scale, 0–10, higher = better quality) — overall quality was rated as "high"

**RoB 2 tool** (Cochrane Risk of Bias tool for randomised trials) — assessed selection bias, performance bias, detection bias, attrition bias, reporting bias

**Statistical analysis:** Data were analysed using Stata-MP 18.0. Effect sizes were calculated as Hedges' g (a standardised mean difference corrected for small sample bias). A random-effects model was used, which assumes the true effect varies across studies — this is appropriate when studies differ in populations, protocols, and settings. Heterogeneity was assessed using I² (percentage of variation due to true differences rather than chance). Subgroup analyses compared whole-body vs. partial immersion at each time point. Sensitivity analyses tested whether any single study drove the results. Publication bias was assessed using funnel plots and Egger's test.

**What this design can prove:**

A meta-analysis of RCTs provides the strongest evidence for causal effects — because each individual study randomised participants, we can be confident that CWI caused the observed differences (not some confounding factor)

The large number of studies (30) and participants (~600) gives good statistical power to detect small-to-moderate effects

Subgroup analyses can test whether whole-body vs. partial immersion differ

**What this design cannot prove:**

**Cannot determine optimal dose:** Temperature and duration varied across studies (10–15°C, 11–15 min), but the authors did not analyse dose-response relationships

**Cannot determine long-term effects:** All studies used a single CWI session — effects of repeated daily CWI over weeks or months are unknown

**Cannot determine mechanisms:** While the authors discuss physiological mechanisms (vasoconstriction, reduced inflammation, hydrostatic pressure), the meta-analysis only tests whether CWI works, not how

**Cannot rule out placebo effects:** Participants cannot be blinded to cold-water immersion (you know you're sitting in cold water), so subjective outcomes (DOMS) are vulnerable to expectation bias

**Limited generalisability:** Results apply to young, healthy, active males after a single bout of muscle-damaging exercise — not to clinical populations, older adults, or chronic training contexts

**Major methodological weaknesses:**

**Publication bias detected for CK:** The funnel plot and Egger's test suggested that small studies showing no effect (or negative effects) of CWI on CK may be missing from the literature. This means the true effect on CK could be smaller than reported — or even zero.

**High heterogeneity for DOMS:** The I² statistic for DOMS was likely substantial (exact value not reported in abstract), meaning the effect varied considerably across studies. This reduces confidence in the pooled estimate.

**No analysis of sex differences:** With so few women included, the authors could not test whether CWI works differently for females — a significant gap given known sex differences in thermoregulation, pain perception, and muscle damage response.

**No analysis of exercise type:** Different exercise protocols (eccentric, plyometric, sport-specific) may produce different responses to CWI, but this was not analysed.

**Primary outcomes (pooled across all studies, all immersion types):**

**DOMS (subjective soreness):** CWI significantly reduced DOMS compared to passive rest. Effect size: g = –0.40 (95% CI: –0.64 to –0.16, P < 0.01). This is a small-to-moderate effect. The benefit was most pronounced at 24 hours post-exercise.

**CK (muscle damage marker):** CWI significantly reduced CK levels. Effect size: g = –0.24 (95% CI: –0.37 to –0.10, P < 0.01). This is a small effect. However, publication bias was detected for this outcome, meaning the true effect may be smaller.

**MVIC (maximal strength):** No significant benefit. Effect size: g = 0.08 (95% CI: –0.08 to 0.23, P > 0.05). CWI did not improve strength recovery.

**CMJ (explosive power):** No significant benefit overall. Effect size: g = –0.02 (95% CI: –0.17 to 0.13, P > 0.05). CWI did not improve jump performance recovery.

**Subgroup analysis: whole-body vs. partial immersion:**

**No significant difference between whole-body and partial immersion** for any outcome at any time point (0–72 hours). The between-group P-value was > 0.05 for all comparisons. This means both methods work equally well for reducing soreness and CK.

**Critical finding for CMJ at 0 hours (immediately after CWI):** Partial immersion significantly *impaired* explosive power immediately after the intervention. Effect size: g = –0.94 (P < 0.01). This is a large negative effect — meaning if you do a partial leg-only cold plunge, your jump height drops substantially right after. Whole-body immersion did not show this immediate impairment.

**Timing of benefits:** The primary biochemical (CK) and subjective (DOMS) benefits were concentrated at 24 hours post-exercise. By 48–72 hours, the differences between CWI and control were smaller and often non-significant.

**Sensitivity analysis:** The main results were robust — removing any single study did not change the conclusions.

**In plain English:**

**DOMS (soreness):** On a 0–10 pain scale, CWI reduced soreness by about 0.4 points on average — roughly equivalent to the difference between "mild discomfort" and "no pain." This is noticeable but not transformative. If your typical post-workout soreness is a 6/10, CWI might bring it down to about 5.6/10.

**CK (muscle damage):** CWI reduced blood CK levels by about 24% of a standard deviation — a small reduction. For context, a typical post-exercise CK spike might be 500–1000 U/L; CWI might reduce this by roughly 100–200 U/L. Whether this matters for your actual recovery is debatable, since CK doesn't directly predict performance.

**MVIC (strength):** No meaningful effect. If your max squat is 100 kg, CWI won't help you recover that strength faster than just resting.

**CMJ (explosive power):** No benefit overall, and partial immersion *worsens* jump height immediately after by about 0.94 standard deviations — a large drop. If your normal vertical jump is 50 cm, partial CWI might drop it to ~40 cm for the next hour or so.

**The key practical takeaway:** CWI is a mild pain reliever and a mild biochemical "band-aid," but it does not restore your ability to produce force or power. If you need to perform again within a few hours, skip the cold plunge — especially a leg-only plunge.

**What the authors acknowledge:**

Publication bias was detected for CK — small negative studies may be missing

High heterogeneity in some outcomes (particularly DOMS)

Only English-language studies were included

The number of studies in some subgroup analyses was small (e.g., only a few studies measured CMJ at 0 hours for whole-body vs. partial comparison)

**What a critical reader would note:**

**No blinding:** Participants knew whether they were in cold water or resting. For subjective outcomes (DOMS), this is a major confound — people who believe cold therapy works may report less pain. For objective outcomes (MVIC, CMJ), this is less problematic but still relevant (motivation effects).

**No sham control:** The ideal control would be thermoneutral water immersion (e.g., 22–24°C) to control for hydrostatic pressure effects. Most studies used passive rest, which cannot separate the effects of cold from the effects of being in water.

**Single session only:** All studies tested one CWI session after one exercise bout. Real-world athletes often use CWI repeatedly across a training week. The effects of repeated CWI on adaptation (muscle growth, strength gains) are not addressed — and prior research suggests chronic CWI may blunt hypertrophy.

**Sex bias:** With only ~20 women across 30 studies, results cannot be generalised to females. Women have different thermoregulation (higher body fat, different hormonal cycles), different pain perception, and different muscle damage responses.

**No dose-response analysis:** The authors did not analyse whether colder water (10°C vs. 15°C) or longer duration (15 min vs. 11 min) produced larger effects. The "standard" dose of 11–15°C for 11–15 min was assumed but not tested.

**Exercise protocols varied widely:** Some studies used eccentric leg extensions, others used plyometrics, others used sport-specific drills. The type and magnitude of muscle damage likely differed, but this was not analysed as a moderator.

**No long-term follow-up:** Outcomes were only measured up to 72 hours. Whether CWI affects recovery beyond 3 days is unknown.

**Industry funding not reported:** The authors did not disclose whether any included studies were funded by cold therapy equipment manufacturers.

For someone running their own n=1 experiment:

### What to test

**The intervention:** A single session of cold-water immersion at 10–15°C for 11–15 minutes, performed immediately after a muscle-damaging workout (e.g., heavy eccentric exercise, high-volume resistance training, or intense plyometrics).

**Two versions to compare:**

**Partial immersion:** Water level at or below the iliac crest (hip bone) — essentially a leg-only cold plunge

**Whole-body immersion:** Water level up to the navel or sternum

**The comparator:** Passive rest (sitting quietly at room temperature for 11–15 minutes)

### Minimum meaningful duration

**Single session test:** You can test this in one workout cycle. Do a standardised muscle-damaging workout, then immediately do CWI (or rest