A good Article on Hypothermia appeared in my reading list recently. The single most important point in this article is that hypothermia takes time a message I have been pushing for years. However, time and again alarmist and misleading information is put about by reputable organizations up to and including the RNLI that suggests hypothermia can set in or kill you in just a few minutes.
As the article explains there is a gasp reflex (cold shock reflex) from sudden immersion in cold water (walk into a cold shower if you want to try this) and clearly if your face is underwater that can be almost instantly fatal.
Hypothermia takes time, though the exact time will vary with water temperature, alcohol consumption, natural body insulation, and simply how warm you are to start with. Nevertheless as the article points out, long before full hypothermia sets in ability becomes impaired so that you may well be unable to make even a short swim back to safety.
Perhaps the most relevant part for cold water swimmers concerns the description of the ‘recovery’ stage. It is all very well to say “wrap up, do not move, get warm”, but that is a luxury swimmers do not have. Arriving back on river bank or beach the imperative is to get warm as quickly as possible because the immediate problem is ‘afterdrop’.
After the exertion of swimming for a few moments all seems well, but removed from the water the response of the body is to once more circulate blood from the core back to the extremities that have been experiencing reduced blood flow in order to retain heat in the core. Now of course cold blood is circulating back into the core and the shivering and discomfort of afterdrop sets in. There is perhaps barely time from exiting the water until shivering becomes so severe that it becomes a challenge to tie shoe laces.
This is the point at which following the advice in the article one would sit still, drink warm tea and wait the shivers out. Some people do indeed go in for wrapping up in a swimming robe and/or hugging a hot water bottle or get in their car with the heater going. My problem with the latter is that all the layers just put on are as effective at keeping warmth out as warmth in. Besides recovering from the shivers can take an hour and who has that long to sit and warm up? Whilst driving with the shivers would I imagine be as dangerous as driving whilst drunk.
Therefore there is little choice left in the matter; if sitting still is not an option then getting moving is not a choice it is the only option. It is my preferred option. I am not suggesting attempting a half marathon, not wearing all those clothes anyway, but a good stomp certainly gets the warming up process started.
For local swimmers here in Devon this is a timely discussion. The temperature of the river water is down almost 5°C on just two weeks ago; 8.5°C yesterday afternoon in the sunshine but only 7.5°C this morning after the frost. The sea temperature has also started to drop, though it has stayed unseasonably ‘warm’ through October it is now sliding down past 15°C and will probably reach 5-6°C by mid-February. Meanwhile the river can get to minus figures. People will keep on swimming though so it is important to separate fact from fiction and focus on the real dangers and not hypothermia which is simply a word most people recognize but few seem to understand.