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Ice Bath Benefits at Colder Temperatures

Updated: Jun 2

After cold acclimation, only colder temperatures will challenge your psychological resilience


  • Any online articles that claims an "optimum" temperature for an ice bath is wrong -- because there is no optimum. There are different temperatures for different purposes, people, and settings.

  • Joe Rogan likes the mental challenge of having ice in his Morozko, which requires him to plunge at freezing temperatures -- even if Gary Brecka doesn't see any evidence of benefit.

  • A good rule of thumb when starting out is "Go cold enough to gasp, long enough to shiver." As you gain experience with cold, you're less likely to shiver.

  • After cold acclimation, short, freezing temperatures are an effective and time-efficient way to get more out of your cold plunge experience.

The Cold Plunge That Was Too Warm

A new study that sought to investigate the brown fat benefits of cold water therapy immersed ten adults in 28°C (82°F) water for four hours a day, ten times in two weeks. No one who has ever done an ice bath would be surprised to find out that they discovered zero activation of brown fat (Skutnik et al. 2024).

If you're an experienced cold plunger, you're probably thinking "I'd die of boredom if I had to spend four hours in such warm bathwater every day for two weeks" and I wouldn't blame you. As I wrote in How To Increase Brown Fat, it is the sympathetic division of the central nervous system that activates brown fat. That's why I recommend you Set Your Ice Bath to a Temperature That Frightens You.

Without arousal in of fight-or-flight nervous system response, there's no activation of brown fat. However, a study that shows 28°C (82°F) is too warm for cold plunge therapy doesn't answer the important question, "What's the best temperature for an ice bath?"

Thermoregulation is a Complex Science

No matter what wikipedia, or Gary Brecka, or anyone else says, there is no single optimum temperature for your ice bath. That's because the thermoregulatory response in every human being is complex, adaptive, and individual.

The human body undergoes several changes that help it maintain thermal homeostasis in the cold:

  • Vasoconstriction redistributes blood flow from the extremities (limb) to the core, protecting vital organs against heat loss.

  • Piloerection, also called goosebumps, causes hair to stand on end, increasing its insulation effect (McPhetres & Zickfeld 2022).

  • Skeletal muscles shiver to generates heat by burning up glucose and fats in the blood stream,

  • If the body has brown fat, it will begin non-shivering thermogenesis in the body core, warming the blood flowing to the brain and other vital organs.

There are even behavioral and social adaptations to cold, such a huddling together (Gilbert et al. 2010).

Each of these adaptive mechanisms can be improved by cold training. That is, the greater the acclimation of the human body to deliberate cold exposure, the better the thermoregulatory response of that body in the cold. That's why sophisticated thermodynamic models of heat extraction developed for military organizations have typically failed to predict human performance in cold environments, despite millions of dollars worth of research and experimentation.

The same applies to research in cold plunge science. For example, a recent review of more than 140 studies complained that "clear conclusions" are difficult to make because the participants in such studies vary in their previous experience with deliberate cold exposure, gender differences are rarely controlled for, and the environmental conditions of the cold vary widely (Espeland et al. 2022). Nevertheless, their findings reinforced the impression that a regular practice of cold plunge will confer a myriad of metabolic and mental health benefits.

That may be why the scientist who led the study was quoted as saying “You never find anybody who’s doing (cold plunge) who says it isn’t great.” James B. Mercer, an emeritus physiologist at UiT the Arctic University of Norway told Scientific American “They all swear by it. They think it’s the most wonderful thing in the world.”

My experience has been the same. I've done nearly two thousand ice baths now, and I've never regretted a single one. Like Joe Rogan, I'm constantly trying to talk my faculty friends at Arizona State University into doing it, too. The only problem is that when they see the online videos of me neck-deep in ice water, they're naturally reluctant to give it a try.

There is no one best temperature or time for a cold plunge, although a good rule of thumb when starting out is:

Go cold enough to gasp, long enough to shiver.

After Cold Acclimation

Many Morozko customer like Joe Rogan report to me that after their body becomes cold acclimated, they find that temperatures above 4°C (39°F) are no longer interesting to them. Because their circulatory, central nervous, and brown fat systems have become so good at thermoregulation, they find that they need colder temperatures to challenge themselves.

For me, the right temperature is freezing cold and the right duration is about 2-4 minutes. I typically go longer in the summer, because I live in Phoenix AZ where temperatures exceed 45°C (113°F) in July & August. On those days, my Morozko is a welcome relief.

It may be that when Gary Brecka hasn't discovered the benefits of going as cold as I do because he's been looking in the wrong place. For example, in his public statements Brecka often extolls the ice bath as a powerful weight loss therapy.

He's wrong.

I wrote about the misconceptions around ice baths for weight loss in Calories & Cold Exposure. There, I explained that a regular practice of ice bath will remodel fat tissue by reducing dangerous belly and liver fat in favor of subcutaneous fat, it will not do much for overall weight loss. That's why there are no before/after pictures of me online that say "I was obese until I started ice baths, and now I'm ripped."

After six years of daily ice baths, I'm still a 6ft tall, 215lb fat guy in my late 50's.

The real benefits of a true ice bath, with floating chunks of ice in the water, is not found in the metabolic markers, but in the psychological. As I wrote in Ice Bath vs Cold Plunge for Heart Rate Variability, without the anxiety experience of the colder temperatures, there will be no hormetic stress to strengthen the parasympathetic division of the central nervous system.

Unlike the fight or flight sympathetic division, the parasympathetic is the rest and digest division. It controls the involuntary functions of the body like heart rate and unconscious breath. When the parasympathetic is in good tone, it shows up in a measure called heart rate variability (HRV) that is a measure of psychological resilience.

That's where the benefits of colder ice bath temperatures are found.


  • Espeland D, de Weerd L, Mercer JB. Health effects of voluntary exposure to cold water–a continuing subject of debate. International journal of circumpolar health. 2022 Dec 31;81(1):2111789.

  • McPhetres J, Zickfeld JH. The physiological study of emotional piloerection: A systematic review and guide for future research. International Journal of Psychophysiology. 2022 Sep 1;179:6-20.

  • Skutnik B, Keeler J, Hite MJ, Hess H, Tourula E, Walker C, Chapman R. Fourteen Days of Cool Water Immersion Does Not Modify an Indirect Index of Brown Adipose Tissue Activation. Physiology. 2024 May 21;39(S1):1562.


About the Author

Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience.

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