Saturday, 1 September 2018

Hypothermia: What I needed to know before I began swimming in cold water.

The water at the beginning of the season seemed to take an age to warm up, yet now it's nearing the end it feels like it's taken a bit of a nose dive! Not to be deterred I make the (feels like) bold decision to ditch the wetsuit and try swimming in skins. The last time I swam sans wetsuit was over a month ago, when the water was warm, the sky was blue, flowers were in bloom ...  This time, although the water wasn't so cold at 17.3oc, when you're not accustomed or acclimatised to it, it's frankly a bit of a shock when you get in.

I stood on the side of the lake as Shark vocalised many excuses and reasons why she should swim in her wetsuit instead. I reaslised she wasn't being serious when they ranged from tooth damage from shivering to the possibility of it giving her trench foot. I diagnosed a case of acute hypochondria and told her to get on with it.

In our inexperience we entered the water with extreme caution, and closely followed all the instructions from Leon, who was standing on the side. He told us we would be fine by the time we got to the first orange buoy, and he was right. I was expecting at best to have ice cream head, and at worst I'd have the shortest swim in history, however was delighted when neither happened.

We swam for 800 metres before Shark began to feel the cold and wisely decided to call it a day. I wanted to complete a mile if possible and after a quick recce (can still I feel my toes? Yes. Are my hands clawing? No.), I decided I'd be okay to carry on. I'd really enjoyed it, and wasn't feeling the cold, so I carried on. I felt great, and when I got out Shark was waiting, holding my towel and Swimzi ready to put straight on (she's a great swim bud), so I could get dried and warm quickly. I dressed, but as I said before I wasn't feeling cold. This is most likely because I had actually spent the second lap trying desperately hard to keep up with another swimmer (in a wetsuit) who at first sight appeared to be going relatively slowly, but in reality he was actually very, very fast, making keeping up impossible, however all the extra effort meant that I concentrated less on feeling the cold and more on the (fruitless) chase, and so by the time I got out I was exhausted and practically hyperventilating, but not cold.

Shark and I had decided to try and swim once a week without wetsuits for as long as we could tolerate the cold. Swimming in cold water is very much unchartered territory. I realised after our swim that I had not really much idea of how my body would respond to the cold, and actually when I should get out. Just checking if my feet and hands were cold or not wasn't at all thorough enough and so I was wanted to find out more about how it will affect me, and Shark, in particular with regards to hypothermia. Shark is the nurse, not me and if I presented the symptoms of hypothermia I'm confident I'd be well looked after, whereas Shark wouldn't be. I think it would bad form to have replace my swim buddy due to neglect, and I'm not entirely sure I'd have many takers if I'm belong honest!

I read loads, and want to share with you what I've found/discovered/learnt. Whilst I usually attempt to make anything I write a bit light hearted, and can pretty much find something (usually me) to poke fun at, when I began looking in more detail about hypothermia it's just too serious, dangerous and important topic to be jovial about. And so...

The next part in this blog has been taken from various websites and people I know. I'm aware that there are various differences of opinion, and some of which some of you will agree and disagree (as some of the websites did) in parts. I'm not an expert, but would like to share what I've found in the hopes that at least one person, other than myself, is better informed, can recognise the symptoms and get medical help and treatment as quickly as possible if necessary. The information I've included is found in the websites, and folks that I know that know far more about it than I do. I've added at the bottom (and not in any particular order - my university professors would not be happy) if anyone wants to read more broadly.

"Hypothermia is a dangerous drop in body temperature below 35C (95F)."

"Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature... When your body temperature drops, your heart, nervous system and other organs can't work normally."

Although most hypothermia happens in low temperatures I have read that even temperatures as mild as 26oc can still be dangerous, and hypothermia is still a possibility, and whilst the colder the water, the quicker and the more likely you are to suffer (there can be other factors involved), there is no time frame for when hypothermia will set in. None of us are immune, and that includes the most seasoned and adapted of swimmers.

Our bodies work best within a certain temperature range, and it's important to maintain this in order to function properly. Many essential chemical reactions that happen in our body can only happen in this range, so when it alters, our body immediately triggers changes to return it back. This is the function of the hypothalamus, which is found in the brain. It collects all the internal and external information (in this instance temperature) and puts changes in place to right the imbalances, to return the body to its status in quo.

When you are swimming in water colder than you, in order to protect your vital organs, your body begins a process. Blood vessels shunt (moving blood to where it's needed) the warm blood away from your skin and limbs towards your vital organs by reducing the blood flow to your extremities. This allows more oxygen to be delivered where it's needed the most. This is to preserve heat in the important bits. Your body is working hard to try and keep your core at its normal temperature. This process is called peripheral vasoconstriction. It's the body's way of protecting against hypothermia.

"Peripheral vasoconstriction basically means the narrowing of your blood vessels that supply your extremities. This means that your blood vessels in the periphery have constricted and hence bring in less blood so that whatever blood is there in the body is diverted to your vital organs"
Dheeksha (studies at Mysore medical College and Research Institute (2020)) 

This process stops when you get out of the cold water and your body then sends the warm blood from the core back to the skin to warm up again. The problem though is that it also cools the blood as it does so, as it's now mixing the warm blood with the cooler blood, and then recirculates the cool blood back to the core, meaning that your temperature will drop further. This is known as the "after-drop." This doesn't happen immediately, and when you exit the water you'll probably feel great for a short time. This is because your cooler blood hasn't reached your core straight away, however within a short space of time, you will begin shivering (great piece of advice was to get dressed quickly after getting out, as it's really difficult when you're shivering).

Shivering is one of our body's immediate reactions to generate heat. Our skin sends messages to the brain, which then sets off a series of warming tricks. Shivering is one of them. It's your muscles contracting and expanding quickly to produce heat to raise your body temperature.

As symptoms of hypothermia can happen slowly, you would think that would give you time to get out in good time, however you may not be aware of them as hypothermia can affect, amongst other things, your cognitive ability; your ability to think clearly, and make intelligent choices, which means you may not even recognise the symptoms. Your brain is so sensitive to cold, and electrical activity slows down in response to it, so your ability to do things and move lessens, making it more difficult to take action. I've included a list of the symptoms of hypothermia, that are listed on several websites below, for your reference:

Symptoms of mild hypothermia include:
  • Dizziness
  • Shivering
  • Hunger and nausea
  • Increased breathing
  • Difficulty speaking
  • Lack of coordination
  • Tiredness
  • Increase in heart rate
  • Poor judgement
  • Cold, pale skin
  • Numb hands and feet
Symptoms of moderate to severe hypothermia include:
  • Shivering, but importantly, as hypothermia worsens, shivering stops
  • Worsening coordination difficulties
  • Slurred speech
  • Significant confusion
  • Drowsiness
  • Apathy or lack of concern (doesn't recognise that they are in any danger)
  • Weak pulse
  • Shallow, slow breathing
  • Paradox undressing -  the person removes their clothes, inappropriately despite the cold because they feel warm.
  • Muscles become stiff
  • Slow pulse
  • Confusion
  • Loss of consciousness
Symptoms of Severe hypothermia include:
  • Shivering stops
  • Extreme confusion
  • A decline in consciousness
  • Weak or irregular pulse
  • slow/shallow breathing
  • coma - can result in death 
Hypothermia will advance quicker in the cold water, and so it's important to get out as soon as possible to prevent further heat loss, get yourself warm, and if necessary, seek medical help. 
When you exit the cold water Outdoor Swimmer magazine recommends the following: 
  • Get dressed quickly and warmly. Immediately after swimming you may feel great as the cooled blood has not yet returned to your core. Best to wrap up warmly before it does. It’s much harder to dress when you’re shivering. 
  • Don’t take a hot shower as this will increase the rate at which cooled blood returns to the core and makes the drop faster and deeper. Cold water swimmers have been known to faint in hot showers. Wait until you’ve warmed up again before showering.
  • Don’t attempt to drive or ride a bike until your core temperature has recovered. Driving and shivering is not a good combination. If your core temperature drops too much and you become hypothermic it can also affect your cognitive abilities. Again, not good for driving.
  • Drink something hot and eat something. Shivering is a highly energy consumptive bodily function. You need to fuel it.
  • Keep an eye on your fellow swimmers. Someone who appears completely fine getting out of the water may be in trouble 10 minutes later and may need your help.
  • Get out of the water before you get too cold as you will continue to get colder after swimming – give your body a margin of safety.
In addition, here are Jonathan Cowie, Editor at Outdoor Swimmer's six tips for cold water swimming….

1. Acclimatise
As the temperature drops in autumn, just keep swimming and your body will get used to the cold.

2. Be safe
Open water can be dangerous. Only ever swim where it is safe, and make sure you can enter and exit the water quickly and easily. Never swim on your own.

3. Wear the right kit
Wear a swimming hat, or two, to help preserve body heat. You can also wear neoprene gloves, booties, balaclava or a wetsuit.

4. No diving
Do not dive or jump in unless you are used to the cold water. Cold water can cause gasping of breath and cold water shock, which can be dangerous.

5. Know your limits
As the temperature drops, decrease the amount of time you spend in the water.

6. Warm up slowly
Don’t have a hot shower as rapid warming of the skin may increase the flow of cold blood from your extremities to your core, and can be dangerous. Instead, make sure you have plenty of warm clothes, wrap up well and have a hot drink.

Swim bud left, me to the right after our swim

So this week the water temperature had dropped almost a full degree to 16.5oc, and I realise with sadness that all hope for an Indian Summer had now completely gone. Shark and I arrived lakeside and readied ourselves for the swim. We were organised and unpacked our clothes and towels in advance of getting out. Shark told me that in addition to her clothes she had also brought a flask of hot Ribena, her ski socks and an extra hat. What she didn't tell me is that she had also brought a hot water bottle, and had wrapped all her clothes around it! A little OTT? Actually possibly not. We swam a mile and at the end when we got out I realised that we are very different, and it seemed that I was able to tolerate the cold a little better than Shark (I put it down to being a farmers daughter - kind of makes you more hardy I suppose). What is clear is that we need to adapt our bodies to tolerate the cold water better (acclimatisation) so that our bodies will grow used to it as the water gets colder still (I'll write more on this in another blog), but in the mean time, I don't mind admitting that I really did feel envious of Shark's forward thinking as I put on my 'at room temperature' clothes, and fully intend to purchase a bottle in advance of next week's swim. What could be better? Other than perhaps someone serving hot chocolate fudge cake on the lake side as we got out... (for medicinal purposes).

Finally, it's a year since I first began writing my little blog, which stared as a way of writing about my recovery, the training and the swim I did last year (Windermere one way). I have been amazed and overwhelmed at the amazing response, and lovely messages of support I have had. After I had completed the swim I was asked if I would consider putting last year’s journey into a book. Going from a blog to an e-book is something quite different, and a lot scarier, however I decided after a lot of consideration to take the plunge (no pun intended) and do it, and finally has now been published this week on Amazon. How amazing (but mostly scary) is that? I hope that for those of you that read it feel inspired to not only take on difficult challenges, but also to never underestimate how far you can push yourself to achieve what you set out to do.

Open Water Woman Swims Windermere is available on Amazon

I also have a "group" on Facebook. It's not really a group, as it's only me, but on it I post more regularly, and I'm also on Twitter and Instagram. You'd be very welcome. Here are the links. 😊

Bibliography and special thanks to:

Leon @Swimyourswim and Chris@Swimzi for you invaluable knowledge.
Jonathan Cowie @outdoorswimmer for your guidance and help.
risks-cold-water after-drop-is-real-and-how-to-deal-with-it


  1. Great article though I'm very jealous of your temperatures! We swim all year round (in skins) in the Irish Sea and the most we can hope for on a 'tropical' summers day is 16 degrees ����

  2. I swim all year round no wetsuit in a lake which gets down to about 10 degrees celcius, amd have acclimatised no problem, and I can't even really say I feel the cold anymore even up to a hour in the water. One trick I have been advised to absolutely avoid the 'afterdrop' in core body temperature that inevitably follows once you get out, is to engage in some vigorous exercise for about ten minutes or so eg go for a run, even run on the spot if necessary. Not sure exactly how it works in the body, all I know that it does...before I did this I used to get the chills for up to an hour afterwards. Also, when starting out in the water I basically paddle as fast as I can for the first minute or so to get my heart rate up, and this seems to get me pretty quickly settled in for the swim ahead.

    1. I do that-- get out, dry&dress fast, get moving. In the water, I start slower than you-- in to my waist, wave hands & legs in the water, rub water over skin, then go- not too fast, as I need to warm up and feel more "fluid" as I swim. After a few minutes, I can pick up the pace.

  3. Super interesting article and experience. I am sharing them with friends in Argentina. Yesterday we swam 35 min in 13°C water, in the Atlantic Ocean (Mar del Plata). Most friends did skin swim (they are mad though already their madness hohoho). We are led and supervised by a very experienced open water swimmer: Claudio Plit

  4. Really interesting read. I recognise some of the mild signs 😂. I only started wild swimming (in skins) in April of this year so it was lovely to have a temperature increase over the summer and to feel the water returning to its prior temperature recently. I think we measured 12C last weekend in the river we swim in. I find wearing gloves/boots and a woolly hat always helps (even if this does seem ridiculous when I'm only wearing a swim suit). That and some good rave moves once dressed on the banking. Rave or bangra moves seem to be a favourite within our group. 😁

  5. I saw one of your comments somewhere either here or on facebook where you said, "Listen to your body".. and that is the fact of it. I am an ice swimmer, but that is not really what it is about for me. I am just an open water swimmer who swims all year long. I adapt my swimming goals according to the conditions. ( both water and air ). Whether it is the ice mile or the ice 100 yards.. the real competition is your own personal body clock. From the moment you get out of your car and head towards the water the clock is starting. The real point of acclimatization to ice swimming is not getting used to the water temp, but learning how your body responds, and when your clock runs out in any given conditions. And it is a constant process. When I had higher body fat my body had a much longer threshold in the ice water.. When I got into great shape, and had better conditioning, my clock is much shorter. But my point is that when people ask me about ice swimming I tell them it is about competing against time and not about distance.

  6. Thankyou.. It would seem we should be careful about how we use hot water bottles... Great for warming the clothes but not directly on the body after swim as it may encourage similar result as warm shower straight after swim?