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Updated: Dec 6, 2022

Afterdrop, drops in temperature; everythings plummeting! So, how do you cope with both types of drop?

Drop in temperature

After a mild autumn, the temperature has plummeted like a rock. For those of us facing our first winter, this means a change in approach and a heightening of senses and experience. Even those of us who have swum through winter before are having to acclimatise carefully. So, how do you cope with this kind of drop?

To start with, think about your swim ahead of time. Broadly speaking, winter swimmers fall into two categories: challengers and dippers. Which one are you?

To decide, it helps to think about why you're swimming through winter. Is it to accomplish something big, such as an ice-mile, ice-kilometre or distance challenge like the Polar Bear Challenge. Or, are you in it purely for the benefits to your wellbeing?

If it's the former, then you're a challenger. This won't be, or shouldn't be, your first year swimming through winter. You need at least one winter to have learned how your body behaves in cold water and to have built up a tolerance for being in ice-cold water for an extended period of time.

If it's the latter, then you're a dipper. You only need to stay for as long as it takes to diminish the stress response to get the full benefit. This can be as brief as one or two minutes. In other words, get in, gasp, feel comfortable, get out.

Winter is for dipping

If you're a dipper, be warned against having a distance or time goal. Your goal is simply to get in and out and warm again. I really can't emphasise this enough, and I'll say it again and again: there is no increased benefit to staying in for longer, but there is an increased danger. If you take away nothing else, let it be this, especially if this is your first winter.

When I first started, Clevedon Marine Lake had only just opened post-renovation and relatively few people were swimming through the winter. We'd swim a fairly rapid breaststroke to the pontoon and back and then get out feeling ecstatic.

The winter swimming community has expanded hugely since then. And a fair few of those who are swimming through their third, fourth or fifth winters are pushing their tolerance this year. This is all fine and dandy, apart from new winter swimmers think that staying in for 15-20 minutes or swimming lengths of the marine lake is normal. People are caring about times and distances rather than just enjoying the moment, and this not only detracts from the experience, it also endangers our health, and, to be blunt, it endangers life.

I don't want to detract from the joy of winter swimming: quite the opposite. I want to ensure that a growing winter swimming community does not bring with it a growing number of casualties. And, as a coach and frequent swimmer, I have seen many a wobble and dealt with serious casualties, so I know what can happen.

The after-drop

Experiencing an after-drop is normal if not entirely pleasant. But what sensations are ok, and when do you know that you've pushed it too far?

If you want to see what attempting an ice-mile does to you, watch this. And this post contains great information on the dangers of swimming an ice-mile. To put it into context, fewer people have complete ice-miles than have swum the channel because it's so bloody difficult. I know a few people who are training to do their ice-miles, but they are all experienced cold-water swimmers.

The after-drop that you can experience after as few as a couple of minutes in the water is where your core body temperature continues to drop after you've got out of the water and started to warm yourself. It usually starts between ten and thirty minutes after you get out and it can take several hours for your temperature to come back up to normal.

With the after-drop, you can feel cold for a very long time. I have also experienced a deeper afterdrop that made my head swim a little and I felt spaced out or dizzy, especially if I physically exerted myself. I have only ever felt this twice, and after food, warm drink and time inside a heated house, I recovered well.

Just for context, today, five hours after a seven-minute swim at 5 degrees, my core temperature (ear thermometer) is still 36 degrees. The after-drop is essentially dropping close to hypothermia, and providing you warm-up properly, won't cause long-term problems and isn't something to worry about too much.

Hypothermia is a medical emergency that happens when your body loses heat faster than it can produce heat. Normal body temperature is around 37C, and clinical hypothermia happens as your body temperature is when it falls below 35C. During an after-drop, your body temperature is heading towards hypothermia, though, providing you've taken precautions, you often won't reach it.

Research into the effects of cold water immersion is still in its infancy. But the Extreme Environments Laboratory at Portsmouth University is currently researching all aspects of the sport. Simon Griffiths, the editor of Outdoor Swimmer magazine, took part in one experiment. "For the experiment, I had to swim in cool water (16 degrees and 18 degrees) for two hours while the researchers monitored (among other things) my deep body temperature," he wrote. "After two hours at 18 degrees, my body temperature had dropped by about half a degree. I towelled off, dressed, put on a coat and hat and drank a hot tea. I was then able to watch my temperature fall to just over 36 degrees before it stabilised and then started climbing back up. The same thing happened at 16 degrees but the effect was greater, the minimum temperature lower and the time taken to stabilise longer. After-drop is real. While your average body temperature may be increasing, your core will be cooling."

Heather Massey, one of the scientists at the Extreme Environment Laboratory, has pointed out that human beings use their intellect to adapt to the cold, not their bodies. In other words, we make fires and build shelters rather than being amazingly good at coping physically. The fact that we only really have two degrees of core body temperature to play with before we're in danger is a testament to that.

So, what's normal, and what are the symptoms of mild hypothermia?

Well, numb toes and fingers are normal. Shivering is normal and good because it's our body's way of warming up. A cold, wet or burning sensation around your middle or a penetrating icy feeling is normal. Just feeling chilly and very chilled out, almost a bit spacy, is normal.

Hypothermia happens slowly and in stages. Signs and symptoms include:

  • Shivering

  • Slurred speech or mumbling

  • Slow, shallow breathing

  • Weak pulse

  • Clumsiness or lack of coordination

  • Drowsiness or very low energy

  • Confusion or memory loss

  • Loss of consciousness

How to experience the highs without the lows

Personally, I don't like the feeling of the afterdrop physically or psychologically (it scares me!), and so I try to avoid it. I do this by following these guidelines:

  • Arrive warm, hydrated and well-fed

  • Avoid alcohol before and after (dipping with a hangover isn't a good idea either)

  • Keep your swim as brief as possible: just allow the cold water shock to pass

  • Wear a swim hat and only take it off to swap it for a bobble hat. Or, swim in your bobble hat!

  • Dress quickly in warm, dry layers

  • Drink a warm drink and have something to eat

  • Go somewhere warm for your post-swim debrief

  • Swim and warm up with friends

  • Don't do anything vigorous or have a shower or bath until you're warm

  • If the pain/after-drop is scary or extreme and outweighs the benefits of winter swimming, then stop. There's always next year.


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