Acclimation To Cold Water

International Ice Swimming Association 1

Competing in an International Ice Swimming Race

Acclimation is a process by which your body gradually adapts itself to cold water through repeated exposure. Through acclimation, it’s possible to improve circulation to the hands during cold water immersion, and to greatly reduce or eliminate cold shock.

Different Strokes
Most people unfamiliar with cold water find 70F (21C) to be quite cold. On the other hand, a competitive open-water swimmer who is used to swimming in 55F (13C) water will probably think that 70F (21C) doesn’t feel very cold at all. Even more extreme are the International Ice Swimming Association competitors who swim in water as cold as 28F (-2.2C). What’s important to your own safety is how you personally respond to cold water.

Acclimation and body fat can make a significant difference in how someone responds to cold water. Repeated exposure to even cool water increases the layer of fat directly under the skin surface (subcutaneous fat).

Body fat is an excellent insulator. Seals, whales, and other warm-blooded aquatic mammals have a lot of this insulating fat - called blubber - which enables them to keep warm while swimming in cold oceans.

Because fat provides insulation from the cold, it can delay incapacitation and hypothermia and also improve physical stamina in the water.

You can easily see this body fat difference by comparing the physical appearance of Olympic swimmers and runners. Swimmers have a lot of subcutaneous fat and a sleek, streamlined look. Runners have very little fat and more obvious muscle definition.

What Acclimation and Body Fat Can and Can't Do

Acclimation reduces the intensity of cold shock

Acclimation does not protect you against incapacitation, swimming failure and hypothermia.
Body fat provides insulation, slows heat loss, and delays incapacitation and hypothermia.
Body fat does not reduce the intensity of cold shock.

A Very Remarkable Swim

An excellent example of how body fat can prolong cold water survival is the remarkable case of Icelandic fisherman Gudlaugur Fridthorsson. On a cold night in March, 1984, Fridthorsson was working on a 75 foot (23 meter) commercial fishing vessel when her nets snagged on the ocean bottom and she capsized three miles off the rugged coast of Iceland's Heimaey Island.

Fridthorsson swam for six hours in 41-43F (5-6C) water before reaching shore. He was the sole survivor of the five-man crew. His remarkable story is well known in Iceland , and in 2012, Icelandic Director Baltasar Kormákur made a first-rate movie about it called The Deep. Fridthorsson's physiology was also studied by cold water researchers, including W.R. Keatinge at the University of London.

How in the world did he do it?

In a word, he was obese. At 6'4' and 275 lbs, he had a chart-busting BMI in excess of 30. His physique was similar to a seal’s.

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