Neoprene and afterdrop: how to keep swimming outside this winter

When lockdown rules eased in May, a friend and I went for a surreptitious dip in a nearby lake. It was exactly what we needed. The shock of cold water provided the thrills, while merging into the landscape brought the bliss. Afterwards, we floated through the woods on a post-swim high. “Shall we do it again next week?” we said.

With public pools closed, we weren’t the only ones rekindling a love of bracing outdoor swims this summer. And staring down the barrel of a second-wave winter, we are also not alone in our desire to continue. The National Open Water Coaching Association (Nowca) has reported a 323% rise in swimmers this October, and more official swimming lakes staying open all year. While, across the country, venues such as Lake 32 at the Cotswold Water Park, near Cirencester, are offering inclusive “mental health” swimming sessions.

For good physical and mental health we need exercise, to be outside in nature and human contact. Cambridge researchers have even recently found that submerging in cold water could help stave off dementia. Meeting my friend each week to embrace the cold has certainly rendered the onset of winter less oppressive. But as water temperatures fall to single figures, what can us wannabe winter swimmers do to ensure we keep going and stay safe?

Experimenting with neoprene (wetsuit material) helps. “A lot of people say neoprene gloves and hats are gamechangers,” says Heather Massey, a senior lecturer at the University of Portsmouth’s Extreme Environments Laboratory. Whether you need a full wetsuit to get in the water, or just a woolly hat, as some diehard skinny-dippers prefer, depends on numerous factors, including how used to cold water you are.

“Between five and six immersions of between three and five minutes,” says Massey, is enough to habituate yourself to the cold shock. After that, don’t worry if you miss a week because even after 12 to 14 months, “you retain about half of that habituation response”. However used to the cold you are, she suggests getting in slowly, rather than diving.

Cold tolerance depends, too, on how active you are in the water, body fat and personal foibles. I don’t mind the skin on my legs tingling, but I struggle to cope with a freezing trunk and neck, so I am swimming in a neoprene vest with a hood around my neck, and gloves and socks. I expect I will graduate to long sleeves before winter’s out.

Bravado is to be avoided in cold water, warns Massey. Besides, you can still feel the benefits in a wetsuit: “You’re going to get a level of cold shock response because the wetsuit will have to flood with cold water, initially.” But make sure your wetsuit is suitable for swimming. Surfing gear often involves protective pads and is thicker, for hanging about on the ocean for long periods, making it too warm and restrictive for swimming.

The triathlon brand Zone3 makes swimming wetsuits and has noticed “a massive shift in business this year from people shopping for events like Ironman and triathlons to open-water swimmers,” says its customer services manager Alina Oprea. Along with neoprene gloves and socks, safety equipment such as inflatable, hi-vis tow floats have just been urgently restocked.

While revelling in the benefits of cold-water swimming, there are added risks to be aware of. If muscles in your arms, legs, hands or feet get too cold, says Massey, “You may start to struggle to coordinate a swimming stroke, and they may go into spasm.” So if a limb starts to feel wayward, get out of the water. If hypothermia sets in, you may be too woozy to notice at all, so reduce your swim time as the temperature drops, swim with others and look out for signs in one another, such as slurred speech and changes in behaviour. “We don’t recommend that cold-water swimming is undertaken by people with cardiovascular problems,” adds Massey.

Finally, never underestimate afterdrop. When you get into cold water, blood vessels that lead to the skin capillaries constrict – which allows less blood to flow through the skin and conserve the core body temperature (AKA vasoconstriction). As you climb out, you may feel too euphoric to notice the evaporating water cooling you further. Then, once you are dressed, the blood vessels dilate, letting that cold blood reduce your body temperature even more, which only becomes apparent when you start violently shivering.

This is why a good post-swim routine is crucial. Bring a hot drink (for warmth and to counteract the dehydrating effects of vasoconstriction, says Massey), wrap up warmly as quickly as possible and have a snack, but avoid warming up in hot showers and baths. This can switch off shivering before your core temperature has recovered and mess with your blood pressure, causing what Massey alarmingly calls “rewarming collapse”.

Fleece-lined hooded robes such as Dryrobe, that are roomy enough to pull your arms inside and get changed under, help to take the freezing fumble out of getting dressed. As does Swim Feral’s brilliant Turtleback bag, which doubles as a changing mat. It was designed by two women who swim in Yorkshire rivers and lakes daily in January to raise money for people who are homeless.

But there is one trick that has kept me swimming thus far that costs nothing. Even if I really don’t feel like it, I go to the lake as planned and allow myself the option of not getting in. I always end up getting in.