This post was a companion to HABITUATION, both of which I wrote in early 2010. Since I revisited and largely rewrote that as Cold Water Habituation, my plan was to do the same in this post also.
Acclimatization (acclimatisation for those of us who forego the use of the z) is a different factor to habituation.
While habituation is simply the process of adapting to getting into cold water, acclimatization is about a person’s ability to stay in cold water for longer.
(Acclimation is the same process but done in controlled or lab conditions).
In brief, as every open water swimmer knows, the more you train in cold water, the better you will be able to tolerate the cold, and the longer you will be able to swim in the water.
Acclimatization is a more difficult and often almost mysterious process than habituation. It takes longer to develop and longer to lose. It tests one far more, requiring a greater willingness to push ourselves.
I’ve luckily gotten to know a lot of cold water swimmers, originally through the Sandycove swimmers group, many of whom say you can think your way through cold, at least up, to a certain point. I know one swimmer and psychologist who helps people in this area, and stress overcoming the fear, that the swimmer should tell themselves that they are warm when they feel the cold, or to focus on different subjects, or to imagine they swimming in warm water, etc. These are classic sports visualization methods that are used to transcend different problems.
I have certainly found for myself that even getting into 6 or 7 º C., after the first minutes of pain, that I now have a definite whole-body feeling of warmth, (excepting feet and hands).
However, there is the problem that physics and the laws of thermodynamics are absolute. A favourite quotation of mine is “eventually the dead hand of the Second Law will hold sway over everything”. (Yes, I have a melancholy bent). However, this alludes to the fact that entropy increases and heat is lost in everything in the universe. As open water swimmers we are affected by such facts as:
- One loses heat in water at 30 times the rate in air (thermal conductivity).
- Heat loss is slower on sunny calm days than overcast windy days which strip body heat away even more quickly.
- You lose 10% of your heat through your head, (in proportion with the rest of your body).
- The ratio of heat loss is proportional to the volume and surface area, so larger people lose heat more slowly as the ratio of volume to surface area is increased.
- Fat is an insulator and slows heat loss.
- Insufficient food and fluids, alcohol intake, illness or not enough sleep all make one feel colder.
- Pockets of changing water temperatures have a significant effect.
- The Second Law of Thermodynamics: In a closed system, entropy increases. In the case of swimming, the closed system is the body, the air and the water. heat will flow from the warm body to the cooler water. You lose heat unless you input sufficient heat energy.
- No-one is immune to heat loss or hypothermia.
Put all that together and all you get is what you already know. You get colder quicker in water, but the rate of change is dependent on a range of factors.
One factor I didn’t put in there is the mental aspect, because it’s difficult to see how thought (Werner Heisenberg & Quantum Mechanics aside :-) ) can have any effect on the rate of change of the system, i.e. how can thought slow your cooling rate? Many experienced swimmers will say you can think your way into extending your time in the water. I’d never been able to say this. I do believe that you can stay calmer, and accept what’s happening, which makes it feel easier.
I think that you get more used to being in cold, and you recognise your early hypothermia indicators better so you can push your limits more. You learn to swim further into your own cold experience. You get better at preparing and recovering. Some of those very experienced swimmers I know have learned to accept and box off the cold, realise it’s there, know the efficiency is decreasing but at the same time know there can be a long gap between the early hypothermia indicators and remaining period during which much swimming can still be done.
There is also the case that with improving habituation, that heart rate and stress hormones decrease, and therefore the person feels better about getting into cold water and less nervous. Less heat will be lost in the initial minutes, which also leads to greater capability. This is the positive adaptive feedback system that I wrote about a couple of weeks ago.
The small improvements drive confidence, the confidence allows the swimmer to push themselves while staying more relaxed. The mental aspect of cold water swimming was the single thing I most struggled to understand in my first few years of winter swimming. It seemed too trite, too easy, without really saying anything useful. It is easy to say that mental attitude allows one to swim longer but it has taken me years of winter cold water swimming to really realise this, to integrate it and to try to convey it. To understand what it means and to comprehend the effect that thought has on my own cold acclimatisation and ability, and not least to be able to explain that better for myself and hopefully others.
It has not been a short journey. If I could do it, so can you.