This article will cover the following points:

• Personal experience
• What is it and how the body’s reacts: cold shock response

• Wim Hof Method
• Risks: heart attack & hypothermia

• Mental & physical health benefits

Personal experience

I take a deep breath in and descend the stairs of a pier into what is literally ice-cold water. The cold hits immediately as my body gets immersed in the water, my breathing becomes shallow and I have an immediate reaction to get the heck away from the water, as quickly as possible. But I stay in. I take a few strokes away from the stairs and focus on calming and deepening my breath. My body becomes more numb to the cold and the constant blabber of my mind slowly quiets down. I keep swimming for a little while longer before heading back to the pier to dry and dress. I do this voluntarily and consciously, but why?

Personally, I do it simply because it feels good. Not necessarily in the very moment that I’m in the water, but definitely afterwards. The feelings of happiness and calmness wash over me every time after cold-water exposure, and usually for the day ahead my anxiety does not feel as overwhelming as usual.

And I am not the only one who has discovered the blissful benefits of cold water swimming. Over the years, cold-water swimming has grown increasingly popular in many parts of the world, [1, 2, 3, 4] and not the least to the credit of Wim Hof, whom I will return to later on in the article. So freezing consciously seems to be in, but I have started to wonder what actually are the mental and physical health effects of cold water exposure?

What is it?

However, before diving into the risks and benefits of this practice, let’s lay some groundwork and look at some definitions. First of all, there is some obscurity about what actually counts as cold water in this context. The authors of an article about cold water immersion explain that dangerous responses to cold water most often happen somewhere between 15C and 10C, so we can say that water is cold when it is under 15C [4].

Another view on this matter is provided in an article by The Guardian, in which a cold-water swimming enthusiast has claimed that between zero and five is cold “but if it gets up to six you’re not ice swimming” [5]. Regardless of the lack of clarity regarding the exact temperatures, there are many claimed health benefits, which are said to result from this insane-looking practice. However, it is vital to keep in mind that, because of these low  temperatures, the swim should indeed be very short (no longer than a few minutes; just a small dip is also fine) except for the very experienced.

The body’s reaction

When you first immerse yourself in cold water you experience something called the cold shock response. This will make you suddenly gasp for air and rapidly increase your breathing. Your skin receptors are attempting to conserve heat by narrowing your blood vessels to decrease blood flow, in order to keep your core warm. This is done by moving blood away from the surface, in a process that is called vasoconstriction. Vasoconstriction also increases heart rate and blood pressure [6]. These symptoms of cold shock response will be dampened if you predispose yourself to cold several times. In other words, the initial gasp, rapid breathing and increased heart rate, as well as increased blood pressure, will lessen over time if you keep returning to swimming [6].

The Wim Hof Method

Popularity in cold-water exposure has increased drastically through the introduction of the Wim Hof Method. Wim Hof, also referred to as the Ice Man, is known for his extreme performances which include: “climbing Mount Kilimanjaro in shorts, running a half marathon above the Arctic Circle barefoot, and standing in a container while covered with ice cubes for more than 112 minutes” [7]. Wim Hof has created a method which he believes will help others to tap into the undiscovered power of their bodies.

This method has three key pillars which are 1) breathing, 2) cold therapy and 3) commitment [7]. To practice this method you do yoga poses, intentional breathing exercises and expose yourself to cold repeatedly [8]. In the additional resources section of this article, you can find more information about this method. But now, what are the actual risks and benefits of cold water exposure?

Physical health risks

Now, let’s look at some risks involved with cold water immersion. Coldwater swimming is no walk in the park and does not come without risks. As a matter of fact, in Britain, 400-1000 deaths linked to cold-water swimming are reported every year annually [9]. As the initial cold shock response radically increases heart rate and blood pressure, people with cardiovascular issues can be subjected to more negative effects and thus should always consult a doctor before trying cold-water swimming [6, 1]. The initial shock for the body can cause cardiac (heart) or cerebrovascular (blood vessels of the brain) issues, which can in the worst case lead to death. This is due to hemo-concentration and thrombus formation, which essentially indicate a blockage in the blood vessels and a possible heart attack [9]. In addition, longer exposure to low temperatures can lead to hypothermia (if the core temperature becomes under 35C), which has detrimental cardiovascular and neurophysiological effects and can lead to death in some cases [9]. Therefore, people who are not accustomed to immersion in cold water, people who suffer from cardiovascular issues, or are of older age should be extremely careful if trying cold-water swimming and must turn to a doctor before attempting the  immersion.

Mental and physical health benefits

After having reviewed some of the very real risks of this rather extreme hobby, let’s move to the benefits. First I will discuss some of the mental health benefits, and afterwards I will review some of the physical ones.

Active cold water swimmers claim that the hobby is good for mental health due to success in reducing anxiety, stress and even depression. These claims can be linked to the release of hormones such as noradrenaline and endorphins that are secreted due to the cold [10]. A study in the International Journal of Circumpolar Health concluded that a group of active winter swimmers in Finland experienced a significant decrease in fatigue, tension and improvement in mood and memory after a four-month winter swimming period, in comparison to the control group [3].

Furthermore, cold water swimming has been shown to act as an antidepressant, as it increases hormones such as catecholamines, which are responsible for the activation of the sympathetic nervous system (increase norepinephrine and β-endorphin), critical for depression  treatment [1]. Similarly, other researchers conclude that “people who practice winter swimming perceived themselves to enjoy better health than the average, and they felt winter swimming improved their mood and decreased tiredness” [11]. Exposure to cold water induces a stress reaction, activating the sympathetic nervous system and increasing the secretion of catecholamines, especially noradrenaline as mentioned above. This is probably one factor behind the refreshing and pain-relieving effect of winter swimming [3]. Although it is difficult to know the exact mechanisms through which cold water exposure affects mental health, due to lack of conclusive research, we can still say that there is evidence, both scientific and anecdotal, pointing towards positive effects of cold water exposure when it comes to overall mental wellbeing.

Moving on, cold water exposure has also  been linked to physical health benefits.

These include but are not limited to improved circulation, reduced inflammation, strengthened immune system, fat loss, improved sleep quality and muscle recovery [1,3,11,12]. As the physical and mental are intertwined, it is good to keep in mind that physical health benefits can also create better mental health and vice versa! There is evidence suggesting that winter swimmers are more resilient to certain illnesses as well as infections. For example, infections in the upper respiratory tract were 40% lower in winter swimmers when compared to a control group, in a study in a study conducted in Germany with 36 winter swimmers [1]. Moreover, researchers Dugue and Leppänen found that diligent cold water swimmers had a higher concentration of leukocytes (white blood cells) in comparison to those who did not practice cold water swimming. White blood cells are the cells of the immune system which protect the body from infections and foreign invaders. This higher concentration of leukocytes can then explain at least some of the heightened immune responses of cold water swimmers [1].

There have been significant scientific results in proving some of the other physical benefits to be true. However, many of the claimed benefits still remain under-researched. Therefore, many of the benefits should be investigated more thoroughly with representative samples and control groups.

In conclusion…

It seems that cold water swimming, if practised in a safe way, can lead to positive mental and physical health outcomes. Yet, more research is required in this field.

Additional resources:

Video - https://www.youtube.com/watch?v=5ro6SNBLTnI&t=386s&ab_channel=GlobalTriathlonNetwork

Video about the Wim Hof Method and influencing the immune system -

https://www.youtube.com/watch?v=A6jqaALpEFM&t=28s&ab_channel=WimHof

Ted Talk by Wim Hof -

https://www.youtube.com/watch?v=zE9FfvPyPZg&ab_channel=TEDxTalks

Reference list:

1. Knechtle, B., Waśkiewicz, Z., Sousa, C. V., Hill, L., & Nikolaidis, P. T. (2020). Cold Water

Swimming—Benefits and Risks: A Narrative Review. International journal of environmental research and public health, 17(23), 8984.

2. Denton, H., & Aranda, K. (2020). The wellbeing benefits of sea swimming. Is it time to

revisit the sea cure?. Qualitative Research in Sport, Exercise and Health, 12(5), 647-663.

3. Huttunen, P., Kokko, L., & Ylijukuri, V. (2004). Winter swimming improves general

well-being. International Journal of Circumpolar Health, 63(2), 140-144.

4. Tipton, M. J., Collier, N., Massey, H., Corbett, J., & Harper, M. (2017). Cold water

immersion: kill or cure?. Experimental physiology, 102(11), 1335-1355.

5. Weeks, J. (2020, March 15). A cold-water cure? My weekend with the ‘Ice Man.’ The

Guardian. Retrieved November 27, 2021, from https://www.theguardian.com/world/2019/may/08/wim-hof-cold-water-immersion-cure-ice-man-outdoor-swimming

6. How To Swim In Cold Water | Essential Cold Water Swimming Tips. (2020, November 26).

[Video]. YouTube. https://www.youtube.com/watch?v=5ro6SNBLTnI&t=386s&ab_channel=GlobalTriathlonNetwork

7. Wim Hof Method. (2021). Who is “The Iceman” Wim Hof. Retrieved November 27, 2021,

from https://www.wimhofmethod.com/iceman-wim-hof

8. Suppmann, F. L. (2021). Reported psychological effects of the Wim Hof method: an

interview study (Master's thesis, University of Twente).

9. Kolettis, T. M., & Kolettis, M. T. (2003). Winter swimming: healthy or hazardous?: Evidence

and hypotheses. Medical hypotheses, 61(5-6), 654-656.

10. The health benefits of cold exposure. (2019, July 5). [Video].

YouTube.https://www.youtube.com/watch?v=c5ajikwjMQE&ab_channel=Dr.DavidGeier

11. Lindeman, S., Hirvonen, J., & Joukamaa, M. (2002). Neurotic psychopathology and

alexithymia among winter swimmers and controls-a prospective study. International journal of circumpolar health, 61(2), 123-130.

12. Knott, J. (2017, September 15). Dipping my toe into cold-water swimming. The Guardian.

Retrieved November 27, 2011, from https://www.theguardian.com/lifeandstyle/the-swimming-blog/2013/nov/29/cold-water-swimming