‘Tis The Season Day 13 – Afterdrop

I’ve talked about getting cold when you’re in the water, what it feels like and how to deal with it, but there’s another little twist to the tale.

When you swim in cold water your amazing body does something clever. In order to protect your vital organs from the cold and keep them functioning it restricts blood flow to your extremities. It works great to keep you alive but it’s got a bit of a bite in it’s tail when you get out. For anyone not used to the cold it can even happen in summer too.

When you get out you often feel all content and toasty (unless it’s windy or -5C in which case you’re just really bloody cold!). As your skin starts to warm up it sends a signal to your brain that you must be warm again so all that lovely warm blood that’s been pooling around your organs starts pumping around your body again. But it’s a closed system, if the warm blood’s going out that cold blood out in your extremities has got to move. So, it ends up back in your core. That cold gets brought right back into your middle and makes your whole body temperature drop.

It can be a rough ride. Just like you feel bad when you have a fever you can feel awful when your core temperature drops. You start to shiver violently, feel dizzy and struggle to speak. This is hypothermia territory.

I’ve had it a few times, the worst being New Years Day. It turns out a hangover affects my body’s ability to control temperature. The Short One however gets it regularly. She’s smaller than me (obviously) and that smaller mass to surface area ratio means she cools that bit faster. My extra bit of padding might have something to do with it too though.

So can you prevent it?

Yep. Getting dressed into a million layers as soon as you get out stops any more heat escaping. Sounds simple, not so much when your hands are numb and feel like clubs, hence the need for baggy I referred to in ‘Tis The Season Day 7 – The Joy of Lots of Layers, That hot water bottle that’s been nestled in amongst your clothes on the bank usually gets stuffed into the waistband of my trousers to get that heat right back at my core. A hot drink helps too, as does hot food.

What we’re realising this year though is that acclimatisation plays an important part too. As I’m swimming more and more over the winter I’m suffering less and less afterdrop. I don’t think I’ve got any speedier at getting dressed afterwards. I genuinely believe my body’s learnt to cope with what I expose it to.

Towards the end of last winter, out of curiosity, I checked my temperature after a cold swim. It was 35C. I should have been shivering quite well by that point. I wasn’t. I hope to see what our temperature profiles look like over this winter properly to see what happens. I do like a good experiment after all.