Brrrrrrrrrrace yourself for a shock when jumping in the water this summer

With the scorching temperatures we’ve been enjoying (or enduring) this summer in the UK, what could be more refreshing for you or your kids than jumping into a lake, a river or the sea for a quick dip?

With the scorching temperatures we’ve been enjoying (or enduring) this summer in the UK, what could be more refreshing for you or your kids than jumping into a lake, a river or the sea for a quick dip?

We don’t want to be killjoys, but it’s really important that you understand the dangers of cold-water shock (something you might not have heard of before) so you can keep yourself and your family safe.

What is cold water shock?

The term ‘cold water shock’ refers to the processes that can happen within your body when you jump into water that’s 15ºC or less. It’s important to emphasis that we’re not talking extremes here, but just a normal outdoor swimming pool or the sea at a typical UK holiday destination.

Average sea water temperatures around the UK are just 12ºC, with most rivers and lakes not even reaching that high. Remember, also, that air temperature heats up much faster than water temperature. This means, in the height of summer, there will be a greater disparity between the temperature of the air and the water than at other times of the year. On a similar theme, deep lakes will hardly warm up at all even during the longest summer heatwaves.

Those who swim regularly in cold water steadily acclimatise themselves to the cold. (We’ve all seen the light-hearted news footage of hardy bathers frolicking in the sea on New Year’s Day) But, if you’re not used to it, then jumping into the sea or a lake can be deadly. 

So how does cold water shock affect you? What happens to the body to make this condition so dangerous?

Stage 1: Rapid breathing

During cold water shock, your body goes through three distinct stages. Firstly, and this is something most of us experience in a minor way every time we jump into a swimming pool, is that sudden gasp for breath, followed by a short period of rapid breathing as your body tries to acclimatise.

This stage can present dangers, in itself. The gasping effect, with your breathing rate anything up to 10 times faster than normal, can lead to a huge mouthful of water being inhaled into your lungs. If this leads to panic and a further intake of water, there’s a serious risk of drowning.

Stage 2: Rising blood pressure

Secondly, as your breathing pattern is altered, your blood pressure rises dramatically. This happens because your body starts urgently pumping body to the centre of your body to try to keep your blood warm.

A sudden rise in blood pressure can be fatal for anyone with a pre-existing heart condition.

Stage 3: Lack of muscle control

Then, thirdly, with your muscles quickly cooling down, you can lose control of them and your ability to get yourself to safety will be compromised. If you haven’t managed to reach a safe place by this stage, then you could be really struggling, Many of those who have survived drowning have said that cold water shock made it harder for them to get back to safety.

People often talk about the dangers of Hypothermia when swimming in cold water, but this is quite different. Hypothermia is gradual, while cold water shock can kill in just a few minutes due to the sudden involuntary body reflexes. Unfortunately, being a strong swimmer won’t help you if you simply aren’t able to control your muscles.

How to overcome the effects of cold-water shock in an emergency

We’d strongly recommend you talk to your children about cold water shock and what to do if it should ever happen to them.

The most important thing is to try not to panic which, we appreciate, can be easier said than done in this kind of situation.

The initial effects of cold-water shock will pass in less than a minute, so don’t try to swim back to safety until they do. Try to relax and float on your back until your breathing feels normal. If there’s anything close by that will help you float, try and grab hold of that.

Then, when you feel able, swim to safety or call for help.

Of course, knowing how to swim will always be an advantage for anyone struggling in the water. If your children haven’t learnt yet, why not book some lessons with Swimtime, the UK’s largest independent swim school. You can find your local pool and course times here.

Published by Swimtime: (updated: )