Open Water is COLD!

Cold-water triathlon training begins with understanding the cold-shock response—not just as a risk but as a physiological benefit. The initial gasp, rapid breathing, and heart-rate spike can boost alertness, circulation, and stress resilience when managed safely. Respect those first 60–90 seconds: enter gradually, keep your airway clear, and slow your breathing before you start swimming. 

Use a short “acclimatisation phase” at the start of every swim. Float or tread water, and blow bubbles for about a minute to regain control, then prepare to breathe harder as you train. If a race doesn’t allow in-water warm-ups, simulate the rhythm on land.  Follow a RAMP warm-up to increase core temperature before getting in. Expect the first few hundred metres to feel uncomfortable until your stroke stabilises.  I can show you my steps to acclimatising in this video.

Equipment matters: I encourage everyone to wear a good wetsuit, a neoprene hat (or double up), socks, potentially gloves (if permitted and you can stand them), and clear goggles if it’s dull, but tinted if it’s bright. In T1, or when you finish swimming and want to change, have warm, simple layers ready; cold hands make everything more complicated. 

You can adapt safely over time to spend longer in the water. Long-distance and ice swimmers prove this repeatedly. When our friends Gerry and Ziggy completed their Ice Miles, Gerry even set a world record. They wore nothing but a hat, goggles, and a cossy in water at 3.4 degrees, and swam a mile!  Alan - whom I watched swim across the English Channel - always focused on the combined air + water temperature. For ultra-distance efforts, anything under 30 °C combined shortened his swims significantly; above that, he could push through long days and nights in the sea.

Research shows that prolonged exposure of the skin to cold water can cause subtle tissue damage, including early-stage cold injury or frostbite that may not become noticeable for years. This is another reason to limit exposure, build tolerance slowly, and be consistent.  The vast majority of health benefits from the cold happen in the first 60-90 seconds during the shock response.  Longer isn’t always better, especially if you are exploring the activity for the cold exposure rather than endurance training.  Your core will cool down more quickly than someone who is exercising. 

Monitor yourself for early hypothermia. Loss of dexterity is one of the first signs. Use the finger–thumb test: tap each fingertip to your thumb, both directions, on each hand separately. If it becomes slow or clumsy - or if your training partner can’t do it - it’s time to get out. A dangerous follow-on symptom is loss of awareness that you’re cold, so always check each other.

After exiting the water, move quickly: dry off, put on easy-to-put-on layers, and let your body gradually rewarm. Delay a very hot shower. On the bike and run, cold hands and impaired judgment can still affect performance, so stay alert and stay well hydrated with a little extra electrolytes.

Stop immediately if you notice stroke deterioration, confusion, slurred speech, blue lips, clawed hands, heavy shivering, or a failed dexterity test.

Our cold-water sessions (CWS) during the winter months have been further risk-assessed by British Triathlon. PeteWibyTriathlOn remains endorsed by Beyond Swim, allowing us to swim in lower temperatures and provide a marked course with safety cover.  However, to give you an idea of normal acclimation expectations, we use the general triathlon guidance for starting focused training sessions at EXPERIENCED OWS in the warmer months. The BEGINNERS tend to need more coaching stops, so we generally start these sessions a month later. Here is the British Triathlon temperature guide:

·       < 11°C: No open-water swimming permitted

·       11–14°C: Very cold — wetsuit compulsory

·       14–18°C: Cold — wetsuit compulsory for most distances

·       18–24.5°C: Wetsuit optional depending on race rules

·       > 24.6°C: Wetsuits not allowed

·       If water < 22°C and air < 15°C, use the “adjusted temperature” chart (combined effect)

I hope to see you at Cold Water Swimming (CWS) or Open Water Swimming (OWS) very soon!

Happy TriathlOn-ing,

Pete