Originally Posted by Mariedut
After a DNF halfway in a 10 km swim due to hypothermia in the 11 degree water, I tried to work out why it happened because I was not feeling the cold and was actually enjoying the swim a lot when I suddenly was dead tired and just wanted to turn on my back and drift for a while. (Not thinking straight any more?)
One of the causes might be not breathing enough and getting enough oxygen. I breath occasionally to the left (on every 3) and then to the right on every 4 strokes- more frequently the latter pattern. I take about 56 strokes per minute so have a long slow stroke.
Another mistake I made was to speed up my stroke rate thinking I could increase my metabolism and stay warm in the extreme cold conditions. This apparently might alsohave been a mistake
11C water is cold (That's 51 in the USA, Belize and Palau). So the Neoprene Sandwich swim cap might be something to consider doing for such swims if you haven't done so a already:
1. Put a latex (or silicone) swim cap on pulling the front down as far on your forehead as possible. Minimize exposed flesh to the cold water.
2. Put a neoprene cap on over that. Again pull it down as far on your forehead as you can.
3. Put your race cap (or another latex cap), on over the neoprene cap. Again pull it down over your forehead as much as you can.
This makes a huge
difference in how your body reacts to the cold. Your body will not have to expend so much energy protecting your head and can use more of that energy keep your toes and fingers warmer.
My last cold water swim was in Lake Coeur d'Alene at the Ironman 70.3. Water temps were about 55 F/13 C. I had a great swim for me and when I pulled my cap off ... my hair was dry. Yes really. Yes it was cold. And yes the water takes your breath away at first and yes my fingers were cold pulling the wet suit off. But it was worse for others.
BTW, that neoprene cap sandwich technique came to me via Emilio DeSoto, founder and owner of DeSoto Sport. I'm just not that
Other than that I don't do much different in cold water (well besides ensuring the wetsuit fits properly). Same breathing rate, same everything. I tend to breathe more to my right than left if I'm not focusing, so I just let myself do that during races barring reasons to breathe other way (Sun in your eyes, breaking waves etc).