I have always swum regularly but, one summer when the pool was closed for a couple of weeks, a friend suggested I went in the sea instead. I never intended to keep on swimming in the sea but I still remember my surprise at noticing how invigorated I felt when I was walking up the beach having swum round the Palace Pier in Brighton for the first time.
Those two weeks have now turned into 13 years of swimming all year round in the sea without a wetsuit. Even on Christmas Day I take a dip. I do it because it makes me feel good and fills me with energy — but it is becoming apparent that it may be good for my health too.
It was through my research on preventing the complications associated with getting cold during operations that I became aware of the benefits of swimming in cold water.
There are many obvious benefits to swimming outdoors, including the exercise itself, green and blue ‘therapy’ (the benefits to mental health of spending time outside) and the sense of community — but cold water appears to offer something else in addition.
Getting into cold water evokes a form of stress response which is significant even at 20˚C. This response is recognisable (though, at colder temperatures, magnified) as our response to any stressful situation — increased heart rate and blood pressure, hyperventilation and the release of stress hormones.
However, repeated immersions — as few as four — diminish this response. While we need to be able to react in this way to many situations, we want to avoid overreacting to the relatively minor threats (trains not running on time, Wi-Fi going down) modern society constantly throws at us. The process of cold water adaptation leads to a reduced, though not abolished, response to stress. Consequently, heart rate and blood pressure don’t go up as much and we can still control our breathing when we get in the water. Cold water swimming could therefore bring benefits to all of us by preventing our overreaction.
It makes sense that the body only has one general way of reacting to stress — it’s hardly likely to evolve one for being chased by lions across the savannah and another when we choose the slowest queue in the supermarket. What we really need, therefore, is evidence of cross-adaptation — evidence that adapting to the cold brings benefits in other areas.
And we do, indeed, have this. Mike Tipton, Heather Massey and their team at the Extreme Environments department in Portsmouth showed that, compared to controls, a group who had been through a cold adaptation programme were better at performing exercise in a low oxygen environment.
Evidence is also beginning to emerge that cold water swimming can provide health benefits. In a collaboration with Portsmouth, Naomi Collier, a fellow Brighton swimmer, is undertaking a PhD looking at this. Our first study showed that, compared to controls, sea swimmers seemed to have a lower incidence and severity of colds during winter.
Our next step will be to study the use of sea swimming as a therapeutic intervention. The underlying basis for this will be the effect of cold water adaptation on inflammation. The inflammatory process is very complicated and cold water adaptation may be more effective than expensive drugs. Furthermore, high levels of inflammation are associated with many conditions such as depression, and low levels are associated with long life.
Currently, we are developing a trial which will use sea swimming as a treatment for depression. While the exact mechanism is unclear, there is growing evidence that inflammation is strongly linked with this condition. Earlier this year, we tested the theory for BBC One’s The Doctor Who Gave Up Drugs. We put a young lady, who was desperate to get off her antidepressants, through a cold adaptation programme one day and then took her for a swim in a lake the next. The transformation into someone bursting with energy and smiles was staggering. She had been taking antidepressants for eight years but within four months she was off them and managing her symptoms with swims in a local lake.
While we are very much at the early stages of research into the therapeutic effects of cold water adaptation, the number of conditions associated with inflammation that may benefit from this intervention is huge. Just in my swimming club we have people who use the sea to control the symptoms of arthritis and inflammatory bowel disease (one, Rob Starr, has published a book about his experiences with the latter). It may also find a role in ameliorating type-2 diabetes and even in reducing complications after surgery.
While outdoor swimming is a joyous and invigorating pastime in itself, in time pragmatic programmes may emerge for its use as a simple, cheap and effective therapeutic process. Just as it was first seen 250 years ago.
Dr Mark Harper is a consultant anaesthetist at Brighton and Sussex University Hospitals. The photographs are by Kevin Meredith.