Ice Ice Baby – Cold Water Immersion: Hot or Not?

Gerda Friedel, MA, ALM

Gerda Friedel

In the hotel basement, past a swimming pool, at the end of the sauna area sits a hellmouth to human bravery. It’s a gateway to bravado and a legendary fountain of youth. It’s a tub filled with cold water. And I was ready to step into the icy cold.

Diving into cold water – some like it and some like it hot

Body contact with cold to ice-cold water has gained high popularity among celebrities, health and longevity enthusiasts alike. Lizzo is doing it; it’s Hailey Bieber’s mood booster and on X Harry Styles posted a picture of him sitting in an ice tub. As a health journalist and wellness enthusiast, I was eager to find out myself: Is it worth the moment of shock when you feel the freeze crushing you?

Scientists have dealt with the health benefits of technically-spoken ‚cold water immerson‘ (CWI) for quite some time. In PubMed – the major archive of scientific literature by the US National Library of Medicine – the first medical review dates back to 1794 by James Currie (1756-1805), who became known for his insights into cold water treatment for fever.

A plethora of popular press articles – my quick Google search gave roughly 41.900.000 results – claims that CWI boosts the immune system, treat depression, enhance peripheral circulation, increase libido, burn calories and reduce stress. However, in 2022 scientsts from Norway in a meta study on CWI stated that, „many of the proclaimed health benefits are based on subjective claims and anecdotal cases.“

Immune system boost, depression treatment, peripheral circulation enhancement, libido booster, burn calorie burner and stress reducer …is it all true?

The medical experts from Norway gathered and analyzed comprehensive data on CWI in a so-called meta study, the gold standard in clinical research. The authors, Didrik Espelanda, Louis de Weerd and James B. Mercer, made „a multiple database survey on published literature to determine the effects on health following voluntary exposure to cold-water immersion (CWI) in humans.“ Starting with 728 publications, the scientists extrapolated 104 medical papers apt for the study. As its title ‚Health effects of voluntary exposure to cold water – a continuing subject of debate‘, indicates, they did not come up with a clear result. Still, the scientifically valid material they examined suggests that regular cold exposure has health boosting properties by reducing inflammation, high colesterol and harmful stress.

Besides the paper’s call for more detail-clearing research, which is often the outcome of medical papers, one term struck me: ‚Voluntary exposure‘. Obviously, the scientists found it important enough to confirm that noone was pushed into cold water against their will. Well, let’s be honest here, to which degree would you plunge into the ice cold voluntarily?

Well, I did. The water of the plunge pool I jumped in had nine degrees Celsius. Nine degrees Celcius isn’t even freezing water, it’s just cold water. In the meta study it says that -2 to +2 degrees Celsius means swimming in ice water, +2.1 to 5 degrees Celsius is freezing water, and +5.1 to +9 degrees Celsius is cold water. These guidelines come from two international associations, namely the International Ice Swimming Association (IISA) and the International Winter Swimming Association (IWSA).

What are the basics of CWI?

On their website, the Mayo Clinic wrote in a January 2024-article that, „A cold plunge or cold-water immersion involves partially or totally submerging yourself in cold water for a few minutes at a time.“
They further state that water should be 50 Fahrenheit, which is 10 degrees Celsius, or colder. You should work your way up from 30 seconds to a minute and later on to five to 10 minutes at a time.

What are your options for practicing CWI? Your choice could be „sitting in a bathtub filled with cold water and ice cubes or jumping into a cold lake or the ocean,“ the Mayo Clinic says.
Want your private CWI? Prices for your own cold plunge tank go up to $20,000.
Also, science says that “Cold shock” is the body’s natural response to sudden cooling of the skin, involving faster breathing and heartbeat. But as you expose yourself more, these defense mechanisms start to relax, research suggests.

What are the clear CWI health and mental benefits mentioned in the study?

Cardio-protective

There is an expanding body of evidence linking inflammation with health and disease. A low inflammation score, for instance, is a predictor for longevity, especially in centenarians, the 2022 Norwegian study says. How does CWI lower inflammation? By increasing the metabolic rate and spiking plasma concentrations of catecholamines – hormones that the brain, nerve tissues, and adrenal glands produce. According to science, the “fight or flight” response of the sympathetic nervous system is a direct result of the multisystem action of catecholamines – which in turn affects the immune system. Through this process, the authors of the meta study say that regular CWI has „caused adaptations influencing oxidative stress markers giving some cardio-protective effect.“

Mental state and pain reliever

Believe it or not: Those practising winter swimming commonly describe the exposure to such an extreme stress as „a joyful and positive exprerienced leisure activity.“ A small study (i.e. with only a small number of partisipants) showed that the stimulation of cold receptors in the skin during cold-water immersion could result in an anti-depressive effect. Above that, the participants self-reported general well-being and indicated a reduction of tension, fatigue and an improvement in mood and memory. Above that, the researchers observed that,“ All swimmers in the study who suffered from rheumatism, fibromyalgia or asthma reported that winter swimming relieved pain.“

„Body hardening“ is the adaptive response to repeated oxidative stress following cold stress. Increased tolerance to stress is a result that can be interpreted as a positive health effect of CWI, the authors say.

Long-term health, metabolic winter and brown body fat

Here, a ‚big shot‘ in the field of longevity comes into play: David A. Sinclair, professor at the Department of Genetics at Harvard Medical School. In a 2014 study, his “metabolic winter” hypothesis would explain why cold immersion supports long-term health. In the study, brown adipose tissue (BAT) is also described as a ‚key player in metabolism‘. Science says that humans have significant amounts of BAT when they are babies; but, until recently, it was thought to be lost by adulthood. New studies suggest that not only can adults have significant amounts of BAT, but that exercise-induced production of irisin – a polipeptide released by the muscle, its concentration in the circulation increases after exercise – causes an increase in BAT and an associated increase in energy expenditure, thus calorie consumption.

The reduction and/or transformation of body adipose tissue is also a highlight of the 2022-meta study. All of the adipose tissue-related effects of CWI „can be considered to be protective against diabetes and cardiovascular disease and therefore potentially could have prophylactic effects on health.“ In that context, the authors suggest winter sports „as a pleasant method of treating obesity“ because of the associated mobilisation of free fatty acids especially by exposing the face to cold temperatures.

What are the study’s caveats?

As already said, the study’s title clearly states that the benefits of CWI are still a subject of debate. The authors wrote that they do not know for sure that these benefits truly come from CWI or just because of other factors, like“ active lifestyle, trained stress handling (meditation, breathing techniques, mindfulness), social interactions, aesthetic environmental surroundings, healthy food and healthy food intake patterns and a positive mindset.“

Official souces like the Mayo Clinic say on their website that „Depending on the environment, such as plunging into an ice- and snow-covered lake, you also may be at risk for frostbite. Too-long exposure also can lead to hypothermia.“ So you better have towels and warm clothing close at hand. „If you have risk factors associated with cardiovascular disease, such as high blood pressure, check with your primary care provider or cardiologist ,“ the Mayo Clinic advices.

And what are mine?

In fact, I haven’t got any. Repetition certainly is a technique for success. During my vacation, after a few days I ended up staying in the plunge pool for four minutes, and I felt a reduction of cold shock after one and a half minutes. Thereafter I thought I could stay in the pool forever. Uncertain about health outcomes, I decided that it might be a good idea to get out.

After my vacay, I started taking cold showers in the mornings. At first I turned on warm water and reduced the temperature gradually while showering. Now I step right into a cold shower. Along with the daily routine my endurance has improved; I can now persist any unpleasant sensations for several minutes. To me, it feels envigorating and I like my skin getting rosy and feeling firm. Something is missing when I skip my morning routine because afterwards, I truly feel happy.