Cold-water immersion (CWI), including ice baths, cold showers, and cold plunges, has become increasingly popular for its supposed benefits on stress, immunity, recovery, and overall wellbeing. The Wim Hof Method (WHM), which combines cold exposure with breathing techniques and meditation, has further fuelled interest in using cold therapy as a tool for health and performance.
But what does the science say? Four recent studies examine the physiological and psychological effects of CWI and the WHM, shedding light on the benefits, limitations, and potential drawbacks of these practices.
Please note, if you are going to try ice bathing, cold shock can be dangerous, potentially lethal. Do it under supervision. As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.
Cold-Water Immersion: Some Benefits but with Caveats
A systematic review and meta-analysis (Cain et al., 2025) explored the effects of CWI on stress, inflammation, immunity, sleep and general wellbeing. Analysing 11 studies with over 3,000 participants, the review found that cold exposure triggers a short-term increase in inflammation, with inflammatory markers spiking immediately and remaining elevated for at least an hour post-exposure. However, some evidence suggested that longer-term CWI use could reduce systemic inflammation.
CWI’s effects on stress were found to be time-dependent. While no immediate reduction in stress was observed, participants reported significantly lower stress levels 12 hours post-immersion. Sleep quality and general wellbeing showed moderate improvements, while mood remained unaffected. The review also highlighted an intriguing immune-related finding: a separate study within the analysis found that participants who took cold showers for 30 days had 29% fewer sick days. However, no measurable short-term improvements in immune function were detected, suggesting that cold showers may enhance resilience rather than directly boost immunity.
Cold Exposure and Muscle Growth: A Potential Drawback
While CWI is commonly used for athletic recovery, a separate systematic review and meta-analysis (Piñero et al., 2024) found that post-exercise cold exposure may slow muscle growth. The review examined resistance training combined with CWI and found that participants who took ice baths after strength training experienced lower gains in muscle size than those who did resistance training alone.
The underlying cause appears to be CWI’s effect on muscle protein synthesis, satellite cell activation, and growth signalling pathways. By reducing the inflammation that follows resistance training - a key trigger for muscle adaptation - CWI may interfere with the natural hypertrophic response. This effect was observed in both trained and untrained individuals. While the overall study quality was rated fair to poor, the findings suggest that those looking to maximise muscle growth should avoid ice baths immediately after strength training.
However, for athletes prioritising recovery over muscle hypertrophy, CWI may still offer benefits in reducing soreness and fatigue.
The Wim Hof Method: Benefits, Limitations and a Lack of Strong Evidence
The Wim Hof Method (WHM), a combination of controlled breathing, cold exposure and meditation, has been widely promoted for its ability to improve immune function, reduce stress, and enhance physical performance. Many people enjoy the practice and especially the community that surrounds it, others not.
A systematic review (Almahayni & Hammond, 2024) examined studies on WHM and found some evidence that it reduces inflammation. Research suggests that Wim Hof-style breathing elevates epinephrine (adrenaline) levels, which in turn increases the production of anti-inflammatory cytokines like interleukin-10 while reducing pro-inflammatory markers. This effect was observed in both healthy individuals and those with inflammatory conditions.
The review also found that WHM breathing can increase stress hormone levels, particularly norepinephrine and epinephrine, creating a physiological state similar to a stress response. However, this did not necessarily translate to a sustained reduction in stress. Participants practicing WHM reported increased energy and perceived resilience but there was no strong evidence that it improved mood beyond the placebo effect. Notably, optimism and expectancy influenced results - participants with higher expectations of WHM’s benefits saw greater improvements.
WHM’s impact on exercise performance was inconclusive. Some studies suggested that the breathing technique altered respiratory parameters, such as minute ventilation and tidal volume, but these changes did not consistently translate into better endurance or strength performance. The review also noted significant limitations in WHM research, including small sample sizes, high risk of bias, and potential conflicts of interest, as some studies involved Wim Hof himself or his commercial training programs.
WHM and Cardiovascular Health: A Reality Check
A randomised controlled trial (Ketelhut et al., 2023) assessed whether WHM improves cardiovascular function and psychological wellbeing. The study tracked 42 participants over 15 days, measuring heart rate variability, blood pressure, arterial stiffness and stress responses. Surprisingly, no significant cardiovascular benefits were found. WHM did not lower blood pressure, improve heart rate variability or enhance arterial compliance - three key indicators of cardiovascular health.
WHM also had no impact on psychological parameters, including perceived stress, positive and negative affect, and subjective vitality. Additionally, participants who performed WHM did not show an improved response to cold stress during a cold pressor test, a widely used measure of cardiovascular resilience. This contradicts claims that WHM improves the body’s ability to tolerate cold or manage stress.
The study raises important questions about whether WHM’s benefits are as profound as often claimed. While previous research suggests that individual components of WHM (such as cold exposure or controlled breathing) may offer benefits, combining them does not appear to create additional advantages for cardiovascular or psychological health - at least in healthy individuals.
How Does WHM Compare to Basic Cold-Water Immersion?
Interestingly, the WHM review found that cold exposure alone did not significantly alter inflammation or immune function, suggesting that the breathing component - not just ice baths - plays a key role in WHM’s effects. However, research on WHM breathing remains limited and similar outcomes could potentially be achieved through other controlled breathing techniques.
The cardiovascular study further challenges WHM’s broad health claims. While some individuals report feeling more resilient or energised after practicing WHM, objective measures do not show significant physiological changes. This raises the possibility that much of WHM’s perceived benefit stems from psychological expectation rather than a direct physiological effect.
Final Thoughts
Cold-water immersion has some benefits, particularly for short-term stress adaptation, recovery and sleep quality. And many people state that it makes them feel great, improving their mood for the day. However, its effects on immunity and inflammation are still uncertain.
CWI after strength training may reduce muscle growth, likely due to its interference with the natural inflammatory response needed for hypertrophy.
The Wim Hof Method does not appear to improve cardiovascular health or stress resilience, despite claims that it enhances cold tolerance and autonomic function.
WHM breathing may play a role in reducing inflammation, but the evidence is weak and results may be influenced by expectation effects.
Many WHM studies suffer from small sample sizes, high bias and commercial influence, making it difficult to separate genuine effects from hype.
Overall, while cold exposure and controlled breathing may offer some health benefits, the boldest claims about WHM are not strongly supported by science. If you find CWI or WHM beneficial, there’s little harm in continuing - provided you practice it safely. However, those expecting a dramatic transformation in immune function, cardiovascular health or performance should approach these methods with a healthy dose of scepticism.
Would you try cold-water immersion, or, the Wim Hof Method? Let me know your thoughts!
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Related Studies
For a complete list of ice bathing and cold water immersion studies please see here.
Cain T, Brinsley J, Bennett H, Nelson M, Maher C, Singh B. Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLoS One. 2025 Jan 29;20(1):e0317615. doi: 10.1371/journal.pone.0317615. PMID: 39879231; PMCID: PMC11778651.
Almahayni O, Hammond L. Does the Wim Hof Method have a beneficial impact on physiological and psychological outcomes in healthy and non-healthy participants? A systematic review. PLoS One. 2024 Mar 13;19(3):e0286933. doi: 10.1371/journal.pone.0286933. PMID: 38478473; PMCID: PMC10936795.
Piñero, A., Burke, R., Augustin, F., Mohan, A. E., DeJesus, K., Sapuppo, M., Weisenthal, M., Coleman, M., Patroklos Androulakis‐Korakakis, Grgic, J., Swinton, P. A., & Schoenfeld, B. J. (2024). Throwing cold water on muscle growth: A systematic review with meta‐analysis of the effects of postexercise cold water immersion on resistance training‐induced hypertrophy. European Journal of Sport Science. https://doi.org/10.1002/ejsc.12074
Ketelhut S, Querciagrossa D, Bisang X, Metry X, Borter E, Nigg CR. The effectiveness of the Wim Hof method on cardiac autonomic function, blood pressure, arterial compliance, and different psychological parameters. Sci Rep. 2023 Oct 16;13(1):17517. doi: 10.1038/s41598-023-44902-0. PMID: 37845341; PMCID: PMC10579249.
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