The Fitness Fixer
The Fitness Fixer

Getting Fitter in 50 Degrees

The Cook Strait, separating the north and south islands of New Zealand, is cold. Reader Dr. Ernie, 52 years old, is training to swim the 26 kilometers across the strait next February. Sixteen Miles of Cold Water started telling about it.

Cold water can be uncomfortable, even incapacitating. Scuba divers wear wet suits in cold water, and dry suits in very cold water, not only for comfort, but safety. According to International Swimming Federation rules (Fédération Internationale de Natation (FINA), marathon swimmers cannot use wet suits to stay warm. English Channel swimmer Ted Erikson is reported to have said that "wearing a wet suit in a marathon swim is like completing the Tour de France on a moped."

Unofficial swimmers can wear whatever they want, but the idea of training in the cold is to improve your fitness by training several body systems so you can generate more heat and better prevent heat loss. The process of increasing resistance to cold injury through regular cold exposure during real conditions is called cold acclimatization. The International Union of Physiological Sciences distinguishes acclimatization in actual conditions, from acclimation, which is change produced in a laboratory.

To be able to swim in the cold, you need to train in the cold water, not just swim in a pool. The idea is not supposed to be to make yourself sick and weak from cold, but to train to become healthier. Dr. Ernie writes:

"Last Saturday I did an 8 km swim: two and a half hours total, out to Somes Island in the middle of the harbour, fortunately dodging the big and small ships with the help of friends in an accompanying dinghy. It was a most gorgeous day. And though tired on the following Sunday, I felt ready to start up again on Monday. It was a tremendous confidence and stamina builder. Today (Sat) after about half an hour in the pool I ventured out and swam about 40 minutes -- water colder, rainy.... but exhilarating. Pretty much a sprint all the way (I have to stay warm enough). We are in our autumn here and will be easing into winter in a few months.

"I feel as if my best chance to make it across Cook Strait is not going to involve miles and miles in the pool, but lots of time in the ocean, hence I'm trying to maximize that, trying to become more and more familiar with its changing moods. I love it and am reaching a tremendous comfort with it even in rough conditions (as this past week). I'd really like to keep up sea swimming through winter without a wetsuit -- the water might get as low as 10 Celsius (50 degrees F).... we'll see."

Next - Dr. Ernie's next story on Fitness Fixer - Better Stretches for Swimming - Cook Strait Update
Read more on cold immersion and cold tolerance in "Diving Physiology in Plain English."

Photo of Dr. Ernie by Martin Woodbridge of Wellington, NZ

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About the Author


Dr. Bookspan is an award-winning scientist whose goal is to make exercise easier and healthier.