Cold water swimming

The Swedish concept of a Kallbad looks like lunacy to anyone not from Scandinavia. How on earth could diving into a freezing cold lake of water be pleasurable?! Well it turns out that cold water swimming can have many more health benefits than previously imagined (even beyond the satisfaction of knowing yourself to be brave enough to take a dip!) With effects ranging from feelings of euphoria to the reduction of chronic pain, this icy hobby is worth learning more about. Inspired by our ambassador Li Elisabet and by the Life Scientific podcast featuring Professor Mike Tipton, this article will take a deep dive into the benefits of cold water swimming.

Read our interview with Li Karlsén here

The dangers of cold water

“Cold water” is usually defined as water that is less than 15 degrees Celsius (1), but because the human body has an internal temperature of 37 degrees Celsius you will gradually get colder and colder if you stay still in water that is 35 degrees Celsius or less. If you’re swimming then the exercise makes your body produce heat, and you can stay warm in any water that is above 25 degrees Celsius. This is really important to know because even in the height of summer the maximum temperature that Stockholm lakes reach is around 19 degrees Celsius. This means that you should always take caution- at no point in the year will the water be warm enough that it is not a danger to you.

With that said, the biggest hazard comes from the cold water response. Whilst hypothermia only sets in after around 30 minutes, the initial immersion can cause reflex responses that can lead to even confident swimmers struggling in the water. When first immersed in cold water, you experience an involuntary gasp in followed by hyperventilation which lasts a few minutes. If your head is under water when this reflex occurs it can lead to water entering the lungs and drowning. In addition, your heart rate increases significantly, which is why cold water swimming is not recommended to those with cardiovascular problems.

Luckily, these reflexes decrease if you swim often! But with that safety announcement out of the way, let’s look at all the incredible things that cold water swimming can do for your body.

 

Increased antioxidants in body

As discussed in the article “Hallmarks of aging, part three”, the body produces reactive oxygen species (ROS) as a byproduct of many reactions. The reactions that produce ROS increase when we are under physiological stress. Whilst a necessary part of many internal functions, having a ROS oxidant level that is too high can lead to cellular damage, and antioxidants are needed to correct the balance. Research has found that regular cold water swimming can lead to adaptive changes in the antioxidant system of the body, making it more ready and resistant to physiological stress (2,3).

Reduction in Chronic Pain

Stress induced analgesia is a body response that reduced our ability to feel pain when undergoing stressful events. Cold water has been shown to be enough of a stressor that this response kicks in, so even though the sensation of being in cold water can be quite painful at the time, it raises your body’s pain threshold (4–6).  This short term raising of the threshold and the reduction in stress and inflammatory signalling molecules is seen as the reason why swimmers have said that they experience a reduction in their pain after swimming (7).

Better insulin sensitivity

When you’ve just eaten a meal, your blood has a higher level of sugar (glucose) in it, so insulin is released to make the body take this glucose from the blood into the cells. Insulin resistance is the cause of diabetes mellitus and can have negative effects on hypertension and cardiac dysfunction. Over the past few years, cryotherapy has been investigated as a way of improving insulin sensitivity in the body (8). One study found that it did this by increasing the number of glucose transporters that were present on the surface of the cells (8). It has been found that cold water swimming can invoke the same effects as cryotherapy, with studies finding that cold water swimmers experienced beneficial changes in their insulin sensitivity over time (9,10)

 

Mental health

Cryotherapy has been found to be an effective add on to depression treatment, improving life quality and mood when combined with standard antidepressant medication (11). It isn’t entirely clear of why this occurs, but it has been noted in other studies that being able to deal with one stressor leads to cross adaptation that improves your ability to deal with other stressful events; cold water swimming has been found to improve surgery outcomes through these mechanisms (12). In addition to this, it gets people outside into nature, and access to “blue water” space has been shown to be beneficial for mental health (13). It is for these reasons that cold water swimming has been put forward as a treatment for depression. In the most salient example, open water swimming was used to treat a woman’s long lasting major depressive disorder. Within three months she was medication free, and remains relieved of symptoms and medication one year hence (14).

Cold water swimming, when treated with appropriate caution, can be an incredible mechanism for improving the health of your body. To try it for yourself, a list of places to swim outdoors in Stockholm can be found at the link.

For more information about the reaction of the body in extreme environments, the podcast that interviews Professor Mike Tipton is highly recommended. Additionally, the website The outdoor swimming society is an excellent resource; many of their articles were written by Dr Heather Massey, who works alongside Mike Tipton at the Extreme Environments Laboratory at the University of Portsmouth.

 

References

1. Tipton MJ, Stubbs DA, Elliott DH. Human initial responses to immersion in cold water at three temperatures and after hyperventilation. J Appl Physiol. 1991 Jan;70(1):317–22.
2. Akhalaya MY, Platonov AG, Baizhumanov AA. Short-term cold exposure improves antioxidant status and general resistance of animals. Bull Exp Biol Med. 2006 Jan;141(1):26–9.
3. Lubkowska A, Dołęgowska B, Szyguła Z, Bryczkowska I, Stańczyk-Dunaj M, Sałata D, et al. Winter-swimming as a building-up body resistance factor inducing adaptive changes in the oxidant/antioxidant status. Scand J Clin Lab Invest. 2013 Mar 20;73(4):315–25.
4. Washington LL, Gibson SJ, Helme RD. Age-related differences in the endogenous analgesic response to repeated cold water immersion in human volunteers. Pain. 2000 Dec 15;89(1):89–96.
5. Huttunen P, Rintamäki H, Hirvonen J. Effect of regular winter swimming on the activity of the sympathoadrenal system before and after a single cold water immersion. Int J Circumpolar Health. 2001 Aug;60(3):400–6.
6. Bodnar RJ, Kelly DD, Spiaggia A, Glusman M. Stress-induced analgesia: Adaptation following chronic cold water swims. Bull Psychon Soc. 1978 Jun 1;11(6):337–40.
7. Huttunen P, Kokko L, Ylijukuri V. Winter swimming improves general well-being. Int J Circumpolar Health. 2004 May;63(2):140–4.
8. Hanssen MJW, Hoeks J, Brans B, van der Lans AAJJ, Schaart G, van den Driessche JJ, et al. Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus. Nat Med. 2015 Aug;21(8):863–5.
9. Gibas-Dorna M, Checinska Z, Korek E, Kupsz J, Sowinska A, Wojciechowska M, et al. Variations in leptin and insulin levels within one swimming season in non-obese female cold water swimmers. Scand J Clin Lab Invest. 2016 Oct;76(6):486–91.
10. Gibas-Dorna M, Chęcińska Z, Korek E, Kupsz J, Sowińska A, Krauss H. Cold Water Swimming Beneficially Modulates Insulin Sensitivity in Middle-Aged Individuals. J Aging Phys Act. 2016 Oct;24(4):547–54.
11. Rymaszewska J, Lion KM, Pawlik-Sobecka L, Pawłowski T, Szcześniak D, Trypka E, et al. Efficacy of the Whole-Body Cryotherapy as Add-on Therapy to Pharmacological Treatment of Depression-A Randomized Controlled Trial. Front Psychiatry. 2020 Jun 9;11:522.
12. Harper CM. Extreme preconditioning: cold adaptation through sea swimming as a means to improving surgical outcomes. Med Hypotheses. 2012 Apr;78(4):516–9.
13. Nutsford D, Pearson AL, Kingham S, Reitsma F. Residential exposure to visible blue space (but not green space) associated with lower psychological distress in a capital city. Health Place. 2016 May;39:70–8.
14. van Tulleken C, Tipton M, Massey H, Harper CM. Open water swimming as a treatment for major depressive disorder. BMJ Case Rep [Internet]. 2018 Aug 21;2018. Available from: http://dx.doi.org/10.1136/bcr-2018-225007