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Pooled review (meta-analysis)

Pooled review of 11 trials in healthy adults: mixed results for cold water

Cain and colleagues · PloS one · 2025

Original title: Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis.

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What the study found

Mixed

Stress fell 12 hours after cold water (SMD: -1.00) but not at other times. Inflammation rose right after (SMD: 1.03) and 1 hour later (SMD: 1.26). Immune tests showed no clear effect. Sleep and quality of life improved; mood did not.

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
11 studies, 3,177 people · healthy adults in 11 randomized trials
What was tested
Cold baths or showers at 7 to 15°C, lasting 30 seconds to 2 hours, compared with before exposure or no cold
What it measured
Several kinds of outcomes
Who has a stake
No stake declared
No competing interests declared.
Journal
PloS one, 2025
Source
PubMed record 39879231. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 11 studies with 3,177 people.
  • •A pooled review is only as strong as the studies it pools.
  • •Measured several kinds of outcomes.
  • ✓No competing interests declared.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

This paper is not on the ladder. It is a pooled review (meta-analysis), and reviews and opinion pieces discuss studies that are already counted on the steps below.

↑ Stronger evidence

  1. Trials in people: muscle recovery and mood

    8

    1 benefit, 1 mixed, 5 no difference, 1 harm

  2. Trials in people: other measures

    8

    2 benefit, 1 mixed, 4 no difference, 1 harm

  3. Trials in people: lab tests or safety

    3

    1 benefit, 2 no difference

  4. Population studies

    3

    2 benefit, 1 mixed

  5. Blood levels and genes

    0

    None among the papers we read.

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “Does cold plunging help recovery and mood?”

Eases soreness a little; mood unproven.

Confidence: low. Based on 30 on-topic papers.

Read the full answer
  • Quoted in “What we found”: A 2026 review of thirteen studies (4105 adults) says evidence does not show cold water improves mood or stress; a review of eleven trials found no mood benefit.
  • Part of the finding “Mood: no clear benefit shown”.
  • Part of the finding “Immune health: fewer sick days, not fewer illnesses”.
  • Summed up in “What reviews found”: Pooled eleven trials with 3177 healthy adults. Stress fell 12 hours after cold water but not at other times. Inflammation rose right after, immune tests showed no clear change, and sleep and quality of life improved but mood did not.

Other reviews on this question

See all 30 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The reviewer corrected 3 fields after reading the abstract. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
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