Winter swimming - all your questions answered

Cold Water Zoom Qa

Seasoned winter swimmers Outdoor Swimmer editor and contributing editor Jonathan Cowie and Ella Foote were joined by Dr Heather Massey, senior lecturer in sport, exercise and health at the University of Portsmouth; Andrew Clarke of Better (operators of West Reservoir); and Gaby Hay of Swim England to discuss winter swimming and answer your cold water swimming questions. Watch a recording of the webinar below.

Below we answer 27 more of your winter swimming questions – including can I swim while pregnant, should I splash cold water on my face, and is it ok to run after cold water swimming?


Q1: Our current sea temp is about 9C and we swim three times a week. We walk in slowly and steadily and then immediately slide into a slow front crawl and swim close to shore. As the sea temperature drops do we need to be concerned about cold shock if we keep up the same pattern? If so, what should we do to be safe? And does it matter that we’re not wearing wetsuits?

A: Your acclimatisation to cold water shock is linked to the water temperature you regularly swim in. Therefore, if the sea cools down gradually, you should adapt to the temperature as it changes. However, you do need to be aware in case there is a sudden, unexpected drop in temperature, or if you take a break from swimming for a couple of weeks and sea cools down in between. We would always recommend that cold water shock can happen, and to keep your head above water until you’re comfortable with your breathing. Note, you can get cold water shock in a wetsuit. The benefit of a wetsuit is that you might be able to swim for longer without getting hypothermic.

Q2: If my outdoor swimming venue closes for the looming lockdown, how will that affect my adjustment to cold water swimming? This is my first season of cold water swimming. If I'm out of the water for a month and the temperature drops by several degrees by early December, how difficult will it be to adapt?

A: While it’s preferable and more comfortable to adjust to water temperatures gradually as winter progresses, it isn’t essential. When you return to the water after a break, and if the water has cooled significantly, you will likely experience cold water shock. Being aware that it’s happening will lessen the impact and help you cope. You should acclimatise again to the lower temperatures after a few exposures.

Q3: My biggest nemesis is afterdrop – would adding a hot water bottle to my changing robe help or is it just a matter of getting dressed quickly and allowing the shivering and afterdrop do its thing. Also - I’m unsure of how long is too long to stay in.

A: Afterdrop, and the associated shivering, is a normal part of winter swimming for many people. However, if you stay cold and shivery for an extended period, or have trouble dressing and looking after yourself, this is an indication you have stayed in too long. You should reduce future swims accordingly. As for the hot water bottle, we don’t recommend it, at least initially. Warming up your skin too quickly with an external heat source such as a hot water bottle may reduce shivering, which is your body’s way of generating heat. Better to dress quickly, with multiple layers, and get out of the wind.

If using a hot water bottle really does help, ensure that it is covered and that you are dry and dressed before adding the water bottle. Only use one water bottle as multiple water bottles may feel more comfortable but will stop you shivering as your skin heats up before your deep body.

Q4: I would be interested if anyone has any knowledge or experience around kids and cold water swimming! My 10-year old Godson came in the sea with me on Sunday (skins). There was a mean wind and I only let him stay in around 5 minutes, but do kids respond the same/differently to adults? Is it particularly dangerous for them? I was aware I wanted to monitor his temperature and kept a close eye on him afterwards. Thanks!

A: We can’t see why children shouldn’t enjoy winter swimming but you do need to take extra care. But, please be guided by the child and don't push winter swimming if it's something they don't want to try. Children, mostly, are smaller and lighter than adults, have a higher body surface to volume ratio and often have less body fat, so they will cool down faster. They will probably also have less experience of cold water than adults and may find it harder to judge when they are too cold (many adult swimmers have poor judgement). We’d recommend having a non-swimming adult present to help any children get dressed quickly afterwards. If you have also been in the water, you may find it difficult to help if your hands are numb, and you also have to dress yourself.

Q5: Does body type make a difference? I am very slight and even in summer get numb toes/fingers. Is there anything I can do to help improve my core temp?

A: There are several questions rolled up together. Yes, body type and size are the biggest factors determining your ability to stay warm in cool water. Slender people typically cool down faster. Please see the attached article for more details on this. Numb toes and fingers can occur at any time of year and may occur due to staying in the water too long, or may be an indication of poor circulation, Raynaud’s syndrome or non-freezing cold injury, and is not necessarily related to your core temperature. If you experience pain with the numbness or are concerned about this it may be worth visiting your GP. If you wish to continue winter swimming you may want to consider wearing neoprene glove and socks.

Being fitter, and therefore being able to swim harder for longer, and thus generate heat through your working muscles, is one way to help keep your core warm, and acclimatisation will make a difference. Slender people can and do swim outdoors in winter but may not be able to stay in the water as long.

Regarding food, we'd suggest simply eating as you would before going for a pool swim.

Q6: How big a problem is surfer's ear?

A: Prolonged exposure to cold water and wind can lead to the growth of bony protrusions in the external ear canal. Common with surfers (hence the name) cold water swimmers are also prone to the condition. The constriction of the ear canal can lead to hearing loss. Ear infections can also be caused by wax and other debris becoming trapped in the canal. Ear plugs will prevent the condition and have also been suggested to help with managing the cold.

Q7: I’m wondering how important the shower is to warm up after and how soon after swimming?

A: Showering immediately after swimming in cold water is not a good idea. While swimming, blood flow to your limbs and body surface is restricted to keep your core warm. Showing in hot water may restart this blood flow too quickly, leading to a drop in blood pressure and possibly fainting. It may also slow or stop any shivering that will be warming you up from the inside. It is best to wait until your body temperature as returned to normal before showering.

Q8: I’ve had a couple of minor panic attacks, thinking I’m too cold suddenly, when in fact I’m not. How quickly do you go from being a bit cold to hypothermia? Is it less than a couple of minutes?

A: What do you mean by “too cold”? There is no need to push yourself into hypothermia when you swim. It’s better to get out too soon than too late. How quickly you become hypothermic depends on a range of factors including water temperature, air temperature, wind, body size and shape. Everyone is different. Please don’t feel pressurised into swimming longer than you feel comfortable or than you’re enjoying. Just do short dips for now. As you become more experienced, you will develop a better sense of what is and isn’t sensible for you. Also, ensure you swim with someone who can calm and reassure you if you do feel panicky.

Q9: I haven’t been able to start outdoor swimming this year yet, is it too late to start now? I’m worried I won’t be acclimatised and should wait until spring. Would you agree?

A: See our answer to Q2. You won’t be acclimatised, but that doesn’t mean you can’t acclimatise. Just start slowly and follow all the usual safety advice. If you swam last winter, you should have some residual acclimatisation that will reduce cold water shock. Make your dips short and be aware that initially you may not be able to swim for as long as you were last time you swam outdoors.

Q10: Any advice on good head-up breaststroke technique in cold water?

A: Head-up breaststroke is useful in winter as your face is often the most painful thing to put in the water. However, keeping you face out of the water can be tiring and put a strain on your neck and back. Practice first in warm water and try to relax into your swim. If you can lower part of your face into the water every stroke you might find that’s a good compromise between face-freeze and neck pain (hopefully you will experience neither).

Q11: Does training help to adjust to the lower temperatures?

A: Yes. Adaption to cold water shock is relatively fast (five or six exposures) but it is temperature dependent. Being acclimatised at 10 degrees will not necessarily protect you from cold water shock at 5 degrees. See the attached article for more on this.

Q12: I am a fairly experienced winter swimmer, recently converted to wetsuits in order to get more swimming in. I never shiver and when I measure my temperature it’s below 35 - how do I work out if I'm hypothermic?

A: Clinical hypothermia is defined as a core body temperature of less than 35 degrees. However, are you measuring your core temperature? An infrared thermometer used in the ear, for example, is of little use when your skin and ear canal has cooled down, as it only measures the skin temperature, but getting a true core body temperature reading is invasive and probably something you wouldn’t want to do at the side of a lake. As you’re an experienced swimmer, it sounds as if your body has adapted somewhat to cooler temperatures and shivering will probably start at a lower body temperature than for an unadapted person, but it will kick in at some point. When swimming, stay alert of other symptoms of cooling, such as loss of dexterity.

While swimming, you may not know that you are hypothermic, but it will be apparent to people you swim with regularly. They will see changes to your swimming style (change in stroke rate, a less efficient stroke, lower legs) and behaviour (slurred speech, errors you wouldn’t normally make). If your swim buddy or other swimmers start asking what you think are really easy questions, such as who is the prime minster? What day of the week is it? Answer them. All they are trying to do is to establish how cold you are and if they ask you to get out of the water, you should get out - they are concerned for you not trying to ruin your swim.

For swim buddies, if you see a swimmers swimming style deteriorate (they become less efficient at swimming forwards and see their legs drop lower in the water) they are definitely exercising muscle cooling, but may also have a cold deep body. You can ask them simple questions they should know the answer to, such as:

- Who is the Prime minister?

- What day of the week is it?

- What is your (partner’s, child’s, dog’s cat’s) name?

From the way they answer you’ll get an idea of the impact the cold is having on their cognitive function. If they answer correctly, immediately and as you would expect, they maybe starting to fatigue from cold muscles rather than have hypothermia. If they slur their speech are really slow to respond and are vague or argumentative (or otherwise out of character) they are starting to display symptoms of hypothermia.

Q13: How important is a tow float, especially for someone wild swimming in rivers, ocean etc. Is this the best safety measure for those swimming in rougher, wild waters with currents etc.?

A: The best safety measure is for you to do a risk assessment each time you swim. Using a tow float is one among several safety measures you could take. They are obviously useful for visibility and it can be reassuring to have a floating device to grab hold of if you want a brief rest (or just to lift you hands out of the water for a few seconds). Some people find them a nuisance in big waves or strong winds, but you might want to ask yourself if you should be swimming in those conditions in winter anyway.

They are also useful for other water users as they make swimmers more obvious in the water. Also having something that fastens rounds you waist is helpful if you need to support a swimmer. Getting hold of a slippery wet swimmer can be quite challenging, having a waist strap can help.

Q14: I quite fancy an Ice Mile this year. I am up to 50 mins at 11.8 degrees…any tips?

A: Extreme winter swimming wasn’t part of our discussion today. An Ice Mile is a big challenge and shouldn’t be taken on lightly. We recommend talking to and training with experienced winter swimmers and at a venue that supervises Ice Mile swims. Keep records of your swims – time in the water and temperature – but also make notes about your recovery. How long it took, how it felt etc.? And use this to guide your training and preparation. Many venues have decided not to allow Ice Miles and similar extreme challenges this year as social distancing regulations prevent the close supervision and support ice milers need. Also, lockdown restrictions will not allow the necessary training to undertake such a challenge.

Swimming in 11-12 degree water is very different to swimming in 5 degree water. Most people will take a couple of winters to train for an ice mile. Also given the current circumstances we need to carefully consider if we should be pushing we should be potentially adding to the stress on the NHS.

Get in touch with the IISA. There are strict rules that need to be followed in preparation for the event (these include a medical and independently verified swim). In addition there are rules on who needs to be in attendance at ice mile attempts. You will need IISA observers and will require a paramedic or doctor to be present. At present this may not be possible with lockdown and the pressure on the NHS. It is best to contact IISA GB for clarification.

Q15: I’ve recently fielded some questions from two pregnant women who are still swimming outdoors and wondering how safe that is. I did a search of the literature and turned up very little about pregnancy and cold water submersion specifically. I’m wondering if you’ve looked into this at all or have any insight on how I can better advise these women on what’s safe?

A: This is a question we’ve been asked frequently but have never been able to find an unequivocal answer as there is so little information out there. This would also be something difficult to test in a controlled scientific manner. Anecdotally, we have heard from a number of women who have swum outside in winter, some of them almost up to full term, without experiencing any problems. You will need to do your own risk assessment. Some factors to consider will be your underlying health and fitness, whether your pregnancy is progressing normally and your existing experience of winter swimming.

In addition, the general rule for exercise in pregnancy is don’t start any new form of exercise, so if you are currently not swimming outdoors, you shouldn’t start now. There are also no fixed rules of how a pregnancy will run, so what works for one pregnancy may not be true of another and each women should take this in to consideration. On the other hand, you are a regular outdoor swimmer, remain healthy and have no ill effects from a short dip that may be ok. However, you should assess how you are before each swim and if you are not feeling well, don’t get in. Keep swims very short and be aware of how well you are before and after the swims. If there are any concerns about continuing to swim whilst pregnant, speak to your GP.

Q16: There are lots of upsides but what are the downsides of cold water swimming? Ear problems? Stroke?

A: Any outdoor swimming, winter or summer, has risks. In cold water those risks are magnified due to the potential for cold water shock: Cold shock can result in drowning, heart attacks and strokes. The muscle cooling process can also cause a loss of strength, early onset of fatigue and swim failure leading to drowning. Hypothermia can lead to unconsciousness, drowning if unconscious when in the water and death. You need to be aware of and manage those risks appropriately. Cold water shock may be more dangerous for people with high blood pressure or heart disease due to the impact it has on the work the heart has to do. However, this is also problematic for people with underlying or undiagnosed heart and circulatory disorders. There is also the risk of non-freezing cold injury. This causes pain and swelling in the digits. We know very little about this condition and not even the ‘dose’ of cold required, which may vary between people. You can reduce the risk of surfers ear by using ear plugs and a swimming hat.

This recent paper describes the level of scientific evidence we have for cold water killing and curing.

https://physoc.onlinelibrary.wiley.com/doi/full/10.1113/EP086283

Q17: What should asthmatics look out for? Is there an extra impact on breathing?

A: Asthmatics should ensure their condition is well managed before undertaking any cold water swimming. You also need to understand what triggers your asthma. Cold water shock may, due to the sudden increase in breathing rate. Hopefully this will decrease as you acclimatise. Note, a wetsuit doesn’t protect you from cold water shock and the tightness may contribute to a feeling of breathlessness.

If your asthma symptoms are increasing you should ensure that you are taking the medication you are prescribed and seek an asthma review from your GP.

See also this article on our website. https://outdoorswimmer.com/blo...

Q18: Do you still get the health benefits of cold water immersion if totally encased in neoprene? And is there any extra health benefits to being in salt water over lake?

A: Many of the reported benefits of cold water swimming are anecdotal. We think it does us good but it’s hard to prove it scientifically. We also don’t know what is the underlying cause of these alleged benefits. Is it the cooling of your skin, the cooling of your core, the fact that you’ve pushed yourself to do something difficult, or the socialisation that comes with it? Given that most of these things happen whether or not you wear neoprene, we can’t see a compelling argument why you shouldn’t get the same benefits. As for salt water versus fresh water, we suspect personal preference and access plays a role here.

Q19: Is it true the fitter you are the more tolerant you can be to cold water swimming (even if you are slim?)

A: See answer to Q5 and also the attached article from Heather Massey.

Q20: Do regular cold water swimmers develop a lower body temperature than normal?

A: Research undertaken in the mid 90s provides evidence that repeated exposure to cold water (head out stationary immersion in 14 °C water for one hour, three times per week for between four to six weeks) reduced skin and deep body temperatures when resting out of the cold. So well adapted cold water swimmers may have a hypothermic and insulative adaptations where the blood vessels close to the skin's surface constrict more quickly. Moving the warm blood after from the skin surface towards the warm deep body.

Q21: Is it true when you splash your face with cold water it helps with the nerves to acclimatise to the cold plunge ahead?

A: We don’t recommend getting the body and the face cold and wet at the same time. Cooling the nerves of the body stimulates a ‘fight or flight’ response which is like putting your foot on the accelerator of a car, it speeds up your heart rate and breathing and increases you blood pressure. Whereas splashing water on your face particularly around your eyes, can be quite calming and is akin to putting your foot on the brake of your car, slowing down your heart rate and breathing. However there are several theories which suggest that cold water exposure of the face and body at the same time (i.e. putting your foot on the brake and accelerator at the same time) stimulates both of these branches of the nervous system and could result in at best a change to heart rhythms (in the young and fit this may be of little consequence), but could result in heart attacks particularly with people with underlying conditions they may not be aware of. This remains a theory but a very plausible one and an experiment that will never be undertaken with humans!

So the simple answer. You can either splash water on you face first, allow the change in sensation to pass and then get in slowly, or get in slowly first, allow the cold shock to happen and then splash your face with water.

Q22: Is it ok to run directly after swimming?

A: We don’t recommend moderate or high intensity exercise immediately after a cold water swim. It can result in a faster and deeper afterdrop response The heart is a muscle, which requires a good blood and oxygen supply, the heart’s supply can be impaired immediately following cold water exposure, particularly if you develop a cold core. Low intensity exercise such as a gentle walk can be taken if you want to exercise.

Q23: Is shivering in a regular cold water swimmer a warning sign?

A: Shivering in any swimmer is a warning sign. Shivering is the body's response to cooling. An acclimatised swimmer will only start shivering at a lower core body temperature, so closer to hypothermia. Shivering is your body’s way of warming up so is a good sign when you are safely on land and getting warm and dry.

Q24: If you’re shivering in the water, is that a sign to get out? Shivering once out, I understand is a good response!?

A: Yes. If you start shivering in the water, please get out and warm up. Shivering once your out is usually fine, provided you’ve wrapped up warmly as soon as you exited the water and are warming up. However, shivering is a sign your body is too cold and you need to make sure you warm up.

Q25: What if you never shiver?

A: You will shiver when your deep body temperature gets colder than usual.

Q26: Will West Reservoir be required to shut down during the coming lockdown?

A: Yes.

Q27: While we have lockdown in November, should we stop cold water swimming for a month whilst lakes and lidos are closed or are there places we can still go and swim?

A: As in the first lockdown, we are encouraged to exercise outside and we haven’t seen any guidance that suggests you shouldn’t swim outside this time. This means you can swim in the sea and other outdoor swimming spots (not commercial venues) as long as you stick to lockdown regulations (e.g. can only meet with one other person). Please remember that swimming in unsupervised locations, especially in winter, carries extra risks. We recommend never swimming alone. The health service is already stretched so don’t create additional burdens by swimming foolishly.

Also, please be aware that your actions may encourage others and whilst you may be fine, others may try to emulate you and not be so fortunate.

01 Cover December

Issue 44 December 2020

  • Finding joy in 2020: Sarah Thomas looks back on a very strange year
  • Motivation: triple Olympian Keri-anne Payne on dealing with changing situations
  • UnstoppaBull: the extreme adventurer who swam in the highest lake on earth
  • Wild swimming: misadventures in the Peak District
  • Soul Cap: solving the problem of swimming with afro hair

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