Summertime – and the swimming is easy. But perhaps you’re already considering your first cold water season and want to know what you – literally – will be getting yourself into? The OSS team doctor Mark Harper, anaesthetist and cold water specialist, shares his personal experience and professional expertise in this extract from his new book, Chill: The Cold Water Swim Cure.
For several summers as a young man, I worked as a lifeguard on the beaches of Brighton. Fortunately, the swimmers I was charged with protecting rarely got into real difficulty. In fact, I never once had to venture into the surf, largely because back in the 1980s neither I nor many of my fellow countrymen and women seemed to have any inclination to set foot in the cold water.
As I grew older and progressed through my career in medicine, I continued to train in the swimming pools of London. After finishing my postgraduate training in anaesthesia, I returned to Brighton for a consultant post in 2003, which is when I started training with Brighton Swimming Club, the oldest such club in England. Happily, I took full advantage of their heated pool, which was open all year, save for two weeks every summer. After hearing me moan about this minor inconvenience, my old friend Jasper suggested I join the club’s sea-swimming group that swam in the English Channel—to my considerable surprise—year-round, regardless of the temperature.
Confident in my abilities, and not in the slightest bit worried about being out of my literal and figurative depths, I was nevertheless apprehensive about swimming in the cold water. I was accustomed to swimming in heated pools, and I knew how cold the sea was, having regularly participated, somewhat reluctantly, in the club’s annual Pier-to-Pier race.
Nonetheless, one morning in August 2004, I joined a dozen or so compatriots and steeled myself for what I knew was coming.
The gloriously evocative lines in Iris Murdoch’s novel The Sea, The Sea came to my mind as I approached the water’s edge: “Trembling with emotion, I tore my clothes off and walked into the sea. The cold shock, then the warmth, then the strong gentle lifting motion of the quiet waves reminded me of happiness.”
The gloriously evocative lines in Iris Murdoch’s novel The Sea, The Sea came to my mind as I approached the water’s edge: “Trembling with emotion, I tore my clothes off and walked into the sea. The cold shock, then the warmth, then the strong gentle lifting motion of the quiet waves reminded me of happiness.”
Fortunately, I didn’t need to tear off my clothes—we had a rather grim but effective changing room—but the progression of emotions and sensations Murdoch describes were spot-on.
First—before I could enjoy the strong, gentle, lifting motion of the quiet waves, let alone the warmth or happiness—I had to endure the very real shock of the cold. There’s no way around it. Getting into cold water is a shock and a stress. Rather than a detriment, however, although I didn’t realise it at the time, this immediate sensation and deeply felt physiological effect is exactly why cold water swimming and other forms of cold immersion therapies are so incredibly effective in reducing symptoms and complications of chronic and acute physical and mental conditions.
Stepping into cold water, you feel the cold engulf every inch of your body, from the soles of your feet to the tip of your nose. At water temperatures of 68 ̊F, or 20 ̊C, the skin vasoconstricts maximally, which is a fancy way of saying the blood vessels that run in our skin completely shut down to insulate the body from the cold. At the same time, stepping into cold water accelerates our heart rate and raises our blood pressure, thanks to the secretion of adrenaline and noradrenaline into our bloodstream.
Mark Harper swimming off Brighton pier
Cold water also has a dramatic effect on breathing in those not used to it. First, it stimulates a large, involuntary “inspiratory gasp”. Anyone who has jumped into cold water, whether by accident or on purpose, has experienced the sharp inhale of breath that occurs reflexively upon submersion. This is followed by rapid breathing, or hyperventilation, which is impossible to override, even for swimmers who are steeled for it.
The consequent stretching of the heart chambers—notably the atria—results in the release of a hormone called “atrial natriuretic peptide.” In simple terms, this tells the kidneys to offload more water, which fills the bladder and leaves cold water swimmers with the slightly uncomfortable need to urinate.
As hard as it is to believe, all of this stress can be good for you.
While I had swum in the sea before, it had always been as a race or messing around with friends. This was the first occasion I had done so with any kind of consciousness of my body’s sensa- tions and of my immediate environment. Since then, I’ve always thought of this as the first swim of my outdoor swimming “career.”
As I emerged from the water, I remembered the words of another writer, Isaac Asimov, who observed, “The most exciting phrase in science isn’t ‘Eureka,’ but ‘that’s funny.’” I was aware of a number of different sensations: My fingertips were numb, and I had a suspicious lack of strength in my hands and a reduced sensation of feeling all over my body. My feet were also somewhat uncomfortable from walking over the beach’s uneven pebbles. Yet, I clearly remember thinking, Hmm. That’s funny. I feel really good.
My fingertips were numb, and I had a suspicious lack of strength in my hands and a reduced sensation of feeling all over my body. My feet were also somewhat uncomfortable from walking over the beach’s uneven pebbles. Yet, I clearly remember thinking, ‘Hmm. That’s funny. I feel really good’.
This made me curious about how cold water could have a positive effect on the human body. The body’s primary aim is to keep the vital organs—the body’s “core”—in the very narrow temperature range of 97.7 to 99.5 ̊F (36.5 to 37.5 ̊C). When the external environment is cool and the body’s not generating heat through movement, it shuts down the blood supply to the body’s “periphery”—the skin and (inactive) muscles, which become relatively cold in order to insulate the core and keep it warm.
When surgery patients are under anaesthesia, however, this insulation system breaks down because anaesthetics block the parts of the nervous system that help regulate body temperature. This causes the core to become hypothermic, or too cold, and the body’s vital organs stop functioning at an optimal level. This is hardly great under normal circumstances, but following the stress of surgery, it can have serious consequences. This is why anaesthetists like me use specially designed hot-air blankets to warm patients throughout their operation.
However, as I read more about the physiological response to cold water immersion, it kept reminding me of the body’s physiological response to surgery. This makes sense because both are evolutionary stress responses. As such, the body reacts to these challenges in the same way it reacts to any other kind of stress, whether we’re going under the knife, getting chased by a sabre- toothed tiger, or running late for an important appointment.
While this stress response has evolved to protect and heal us, following surgery it overreacts, which can exacerbate the adverse effects of hypothermia. This led me to wonder if, by teaching the body how to adapt to the stress of the cold through cold water swimming, it would be possible to reduce the stress reaction in patients undergoing surgery to a “physiological” rather than “pathological” level—and thereby reduce the risk of complica- tions. The more often the body is exposed to cold temperatures, the less intensely the body responds to this exposure and stress as life-threatening.
This was how my initial “that’s funny” moment became a working theory about a therapeutic intervention. If patients went through a cold water adaptation program before their operations, I hypothesised, they could lessen the magnitude of the stress response on their bodies, which would maximise and accelerate their recovery. In 2012, I published a paper suggesting this theory in Medical Hypotheses entitled “Extreme Preconditioning: Cold Adaptation Through Sea Swimming as a Means to Improving Surgical Outcomes.”
The longer I considered this theory, however, the more keenly I suspected cold water adaptation could produce similar mental and physical health benefits far outside of the operating room. Wedding my professional expertise to my newfound passion, I started to study—and practice—cold water swimming in the hope of developing a therapeutic intervention for many of today’s most prevalent chronic ailments and conditions.
Mark dipping in an ice hole
One of the most common comments I hear when I tell people I enjoy cold water swimming is “You must be mad.” How, they often ask, can that possibly be good for you? The answer, in a word, is hormesis, an adaptive response of cells and organisms to moderate and intermittent stress.
Psychologists define resilience as the process of adapting well in the face of adversity, trauma, tragedy, threats, or significant sources of stress. The road to resilience inevitably involves facing distress as part of the process. While stress manifests itself in our consciousness as a psychological phenomenon and in our body as inflammation, its roots lie in our physiological responses to the environment—all those chemical messengers rushing round the body, putting our heart rate up, causing us to breathe fast and shallow, and keeping us on edge so we can deal with the next threat.
Because stress often takes the physiological form of inflammation, it makes sense that a physical riposte exists. A paper by Jonathan Stone and his team argues that the stresses that induce resilience arise from everyday sources like sunlight, food (and lack of food), and physical exertion. At low levels, such stresses trigger a protective response. At higher levels, however, these same stresses can cause inflammation and damage tissues.
One of the most common comments I hear when I tell people I enjoy cold water swimming is “You must be mad.” How, they often ask, can something as stress-inducing as cold water swim- ming possibly be good for you?
The answer, in a word, is hormesis, an adaptive response of cells and organisms to moderate and intermittent stress.
The concept of hormesis is often traced back to an early- sixteenth-century Swiss scientist and physician known as Paracelsus, though his rather magnificent full name was Philippus Aureolus Theophrastus Bombastus von Hohenheim. His best-known maxim roughly translates as: “All things are poison, and nothing is without poison. The dosage alone makes it so a thing is not a poison.”
Basically, high doses of any substance, including water and oxygen, are potentially toxic and even lethal, but exposure to low doses can be good for us because they promote resistance and resilience.
Hormesis—a low-level good/high-level bad model—also applies to physical stresses.
The stresses that induce tissue resilience, as Stone and his team underline, arise from everyday sources, most notably ultraviolet radiation from the sun. Essential to our production of vitamin D, ultraviolet light can, at low levels, improve cardiovascular health, enhance resistance to cancer, and improve immune function, mood, and sleep. Conversely, at high levels, such stresses cause tissue destruction. In the case of ultraviolet light, these stresses include sunburn and, at the extreme, malignant melanoma.
Similarly, excessive exposure to cold leads to hypothermia, but moderate and intermittent exposure to cold allows us to withstand the stress, which produces positive health benefits and gives us the confidence and physical and mental ability to endure other stresses in the future.
Excessive exposure to cold leads to hypothermia, but moderate and intermittent exposure to cold allows us to withstand the stress, which produces positive health benefits and gives us the confidence and physical and mental ability to endure other stresses in the future.
In addition to Stone’s work, reports of stress-induced resilience can be found in journals dedicated to the fields of neuroscience, sports medicine, cancer, healthy ageing, dementia, Parkinson’s dis- ease, and even ophthalmology. The benefits of stress-induced resilience include faster wound healing and a demonstrable slow- ing of age-related degeneration in the brain and other nervous tissue, muscles, and bones. Stress-induced resilience has also been shown to suppress certain kinds of cancers. Basically, a whole raft of physiological effects can contribute to a longer and healthier life—all through exposure to the kinds of stresses that cold water swimming presents, namely exercise, exposure to the elements, and physical challenges.
A recent study, published in Experimental Physiology, showed that swimming exercise decreased depression-like behaviour in diabetic mice by reducing inflammation. Swimming, according to the authors, is associated with both an improvement in mood and a reduction in inflammation, which indicates it might be a useful treatment of depression-related disorders in patients with type 2 diabetes. I would qualify their findings by pointing out how swim- ming in cold water is likely to enhance this effect.
At first, it might seem somewhat paradoxical to willingly expose ourselves to a challenge like swimming in a winter ocean, when the air is also cold, the weather often intemperate, and the sun barely a rumour in the grey sky. Many people might regard this as something to be avoided at all costs. However, voluntary risk-taking can bring some overlooked benefits. For instance, it builds character, which increases self-esteem and enhances psychological resilience, and these can be translated into every other area of a person’s life. Undertaken with an appropriate degree of cau- tion and a healthy sense of fear, cold water swimming offers a controlled, safe, yet exciting challenge. It’s an ideal environment in which a person can experience—and grow accustomed to— moments of stress.