Updated: Mar 15
The cold waters of 2°c have moved on and we’re left with a palpable and triumphant sense of wonderment and bewilderment, at their passing. Triumphant, in that we still swam in those bitter cold conditions; bewilderment because – why and how did we do that?!
Wild winter swimmers know well the claw-like hands and clubbed feet that cold waters induce; the clumsiness of these numb appendages as we dry ourselves, the fumbled attempts to enter clothes. We seek a rapid return to warm and dry but it’s not easy when your hands are claws. The colder the water, and the longer the time spent in it, the more dramatically difficult these simple post-swim tasks become. And that’s before the drop arrives. It creeps and it crawls – before it pounces on its prey. The uninitiated, not knowing this beast, may not appreciate the urgency with which cold hands dress themselves. The drop waits for no-one.
Afterdrop is when your body temperature continues to fall even after you get out of cold water and into a warmer environment. When you swim in cold water, your body shuts down circulation to your skin, pooling warm blood in your core. On exit, the blood recirculates from the core back to the extremities, thus lowering the core temperature in the process. The Drop!
Each of us feels its effects at different times: it can start straightaway, on exit from the water, or it can wait 5 to 10 minutes after leaving the water before it makes itself known. It’s not unusual to feel colder than you did when you were in the water. The afterdrop lingers until we start warming up again. Its effects may last for an hour, or even longer.
Now, as the spring season approaches and as mad March Hares box, the temperatures are on the rise and we might push the duration of our swims – but caution is still required. The water is still cold, and this cold still carries risks. Pushing for those much-desired longer swims, increasing the duration in the cold waters, needs restraint. How we all complacently we say, “The water is so much warmer now. If we coped with 2°C, we’ll be fine at 7°C…” Cold-water swimmers should pay attention to their fellow swimmers, in and out of the water because hypothermia remains a risk.
Hypothermia is a dangerous drop in body temperature. Normal body temperature is around 37°C. Hypothermia sets in when the body’s core temp drops below 35.0°C. Symptoms depend on the temperature.
In mild hypothermia, we start to shiver, mental confusion sets in. Shivering is an involuntary muscle contraction that generates heat. Other muscles, small ones just below the skin, cause the tiny hairs on the skin surface to lift and to trap warm air close to the skin’s surface. But obviously, the body’s reactions are not enough. Putting on warm clothes, embracing a much-loved hot water bottle, and drinking a hot drink can make a massive positive difference when dealing with mild hypothermia. Physical activity helps too; jumping and running around warms up the body – this may explain the unexplained sudden burst of dashing about of winter swimmers!
So, if you’re shivering and feeling cold, mumbling and fumbling about; yes, you have mild hypothermia. You could confirm this with a tympanic, ear thermometer; it’s non-invasive and easy to use. But better just diagnose yourself through those other symptoms and get yourself somewhere warm – and quickly!
In moderate hypothermia, shivering stops and confusion increases. You may know this if you have felt the inability to comprehend simple tasks after a cold swim. Don’t drive!
Sufferers of severe hypothermia will be confused and possibly feeling hot. They may feel the need to take clothes or layers off! When the body’s core temperature has dropped dangerously low, it increases the risk of the heart stopping. It's a medical emergency that needs to be treated in hospital.
The time it takes to get cold enough for hypothermia to set in is dependent on various factors:
temperature of the water
duration spent in the water
experience in these conditions
biological factors, body mass index, body shape, brown fat adaption….
weather conditions, including air temperature
time taken in getting dressed / warm drinks
fatigue level prior to cold exposure.
See our infographic on hypothermia below.
Note that hot showers will increase the rate at which cooled blood returns to the core, thus making the drop faster and deeper and are not recommended.
Cold water has been fun but I am looking forward to warmer waters, to increasing swim distances and durations, to joining with friends for outside swimming in lakes, oceans and rivers. I am looking forward to the feeling of stretching out my arms, finding the groove and pace, settling into a comfortable rhythm, and following the flow in the water.
It’s not long now before we can join with friends in small groups and, later in the year, larger events will be allowed. I am very excited to say the Lock to Lock swim series is going to take place this year starting the end of June 2021. These much loved and deeply appreciated events are celebrations of the open-water wild swimming magic. It has been suggested that it’s the best kept wild swim secret. If you love open water swimming and have never done a Lock to Lock swim before, I recommend booking your place soon. The number of participants are kept low to avoid a mass event feel – but are large enough for a vibe of excitement and connection to your fellow wild swimmers.
By June, we can hope that the Thames will be warm enough to avoid meeting the drop – but we’ll be ready for anyone who is affected. (And there’s hot tea or coffee and cakes at the end for everyone, just as a precautionary measure…!)
Looking forward to meeting you on the day.
Introducing Wild Open Swim Infographics available to have, contact us at email@example.com for further info.
Open Water Swimming Temperatures
The A-Z of Cold Water Swimming