The positive effects of cold water immersion is a topic that has continuously crossed our minds since beginning our project to promote wild swimming in Cornwall. Thankfully we were able to call upon health and wellness expert, Florence Gould, to delve in to the science behind why swimming in cold water makes us feel so good. Florence has recently launched her own wellness website called Bewaved, so if you’re after more health and wellbeing advice then head to her blog to find out more.

Words by Florence Gould

Immersing yourself in cold water is a deeply transformational experience. 

The ‘Why I Swim’ stories shared by Bethany, Lydia and Max all elude to an intuitive understanding that open water has the capacity to heal. This intuition is rooted within our biology and is what ultimately brings people to the water’s edge to take the plunge. Asides from the emotional rewards that the water has to offer, there are a number of physiological benefits of cold exposure which I’d like to outline today.

Submerging in cold water can help improve temperature regulation and speed up your metabolism.

As you approach the waters edge, your senses will begin to heighten. Gently letting your toes submerge, you can feel the chill of the water ripple up through your nervous system… 

It is at this point, the delicate network of blood vessels begin to exercise the cardiovascular system. The extremities of the body are the first to experience a ‘sympathetically-mediated vasoconstriction’ -  the nervous system is beginning to constrict blood vessels and shunt blood to its core (Cheung 2015). A reaction such as this represents an initial line of defence against cold environmental temperatures developed through our evolution to protect the body from hypothermia. As this progresses the body will also attempt to increase its ‘resting energy expenditure’ through thermogenesis (aka shivering) to try an ‘counteract heat loss’ (Brychta and Chen 2017). This heightened energy expenditure has gained notoriety as a method through which people are able to offset obesity (Palmer and Clegg 2017). As the water gets colder the energy needed to maintain homeostasis increases, which over a period of time, can help to support weight loss in overweight individuals, however, this is not the only recognised health benefit of cold exposure. 

It promotes the production of hormones that will help you sleep better and that will counteract the effects of depression and anxiety.

Cold exposure has been utilised as a therapeutic tool within many different cultures across the world. In 1978, Japanese scientist Dr Yamachi developed total emersion cryotherapy chambers to help treat chronic pain and inflammatory issues (Banfi, Lombardi and Colombini et al 2010). Further research conducted in Finland found a significant increase in blood levels of norepinephrine while conducting blood tests before and after cold exposure (Pääkkönen and Leppäluoto 2002). This is an incredibly significant finding as this particular hormone and neurotransmitter plays a very important role in regulating healthy sleep cycles, attention capacity and ability to encode memories and regulate emotions (Mitchell and Weinshenker 2011). In fact, those who experience depression, anxiety, PTSD, ADHD and substance abuse almost always have issues relating to high or low norepinephrine levels. This knowledge helps us to piece together why it is that swimming in the cold water can have such a significant impact on our perceived wellbeing. Norepinephrine is generated within the adrenal glands alongside dopamine and adrenalin and the process whereby it is released in such high quantities relates to adrenal shock and the hermetic stress response caused by the chill of the water. Norepinephrine increases the rate and intensity of the heartbeat, alongside blood pressure in turn helping to break down fat cells and increase sugar levels, providing energy for the body while in the midst of the chilly water. 

Cold water instigates your bodies defences and can help reduce the risk of chronic diseases.

Following on from what is in effect a shock response, your body and all of your cells are thrust into a process of mitochondrial activation. The mitochondria is the powerhouse of the cell and mitochondrial dysfunction has been recognised as an important contributor to an array of human pathologies including all chronic diseases and the process of ageing itself (Green and Reed 1998). It has been shown that biological stressors such as exercise but particularly cold exposure, trigger an increase in a cells energy demand and therefore its capacity to undertake mitochondrial biogenesis. This is essentially where a cell increases its mitochondria mass and thus its ability to function effectively. Returning to the powerhouse metaphor; imagine the cell suddenly finds space to house two batteries instead of one. The capacity for mitochondrial biogenesis has been shown to decrease with age, and decreased function has been proven to be associated with common issues such as diabetes, cardiovascular disease and integral degradation of our DNA structures (Medeiros 2008). To put this simply, the shock response a cell experiences when exposed to the cold can help to support your cells to function better for longer, thus reducing the chance of developing a chronic disease. 

Mitochondria play a key role in maintaining energy homeostasis in metabolic tissues including adipose tissues. Adipose tissue is broken down into two groups; white adipose tissue (WAT), and brown adipose tissue (BAT), which as a characteristic contains many more mitochondria (Enerback 2009). This brown fat is what allows babies to regulate their temperature effectively when they have not yet developed the necessary muscles to shiver, playing a huge rule in the process of thermogenesis mentioned previously in this essay. As we age, the levels of brown fat tissue inside of our bodies decreases and is replaced with white fat tissues which do not offer nearly as much mitochondrial capacity, albeit a little insulation and energy storage. As you expose yourself to the cold however, you are stimulating this small store of brown fat that adults posses, subsequently increasing the bodies resting energy expenditure which supports homeostasis and reduces the capacity for disease to manifest inside the body (Bartelt et al, 2012). This process was originally considered to relate towards nervous system activation and behavioural changes such as our eating habits when cold. However, new research in the field of cold exposure has shown that by making even modest changes in body temperature, we can activate our stem cells to form brown fat at a cellular level. 

In essence, cold exposure is helping to keep the body young and supple, able to fight off sickness and ill-health. It helps you to lower inflammation and recover from injuries, both physical and mental, regaining your confidence and energy levels. Over time your body will begin to adapt to the environmental shock and become stronger and more able to support itself moving into the future. It is, when you think about it, so simple and easy to access, and yet also a little scary. Placing yourself into a situation which feels initially uncomfortable is a bold act of self love, something which you can only trust in once you have experienced it for yourself. As a concept there is so much more research which needs to be done, however I do believe that once you try it for yourself, you will understand and then the rest is history. 

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