Long-distance triathlon glossary·EAU FROIDE

Cold water swimming: adapting to water below 18 degrees C

Swim

Swimming in water below 18 degrees C, requiring physiological adaptation and specific gear.

Cold water immersion (below 18 degrees C) triggers the 'cold shock response': sudden HR spike, reflex hyperventilation and peripheral vasoconstriction in the first 30 seconds. This response causes dangerous involuntary inhalation. Adaptation occurs over 3-6 progressive sessions. Below 15 degrees C, technique degrades (numb fingers, loss of proprioception). In Ironman competition, wetsuits are mandatory below 20 degrees C (WTC regulations). Acclimatisation also reduces cold-induced headaches in very cold water.

In TriPaced:

TriPaced displays the expected water temperature in race details when available from weather forecasts. If below 20 degrees C, a 'wetsuit required' badge appears in the Plan view for your race week.

Related terms

  • CSS : Critical Swim Speed
  • Swim zones : from Z1 recovery to Z5 VO2max
  • Open water : swimming in lakes, sea or rivers
  • Sea legs : wobbly legs out of the water
  • Wetsuit : triathlon neoprene suit
  • Drafting in swimming