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Get Out There Magazine: How our bodies function in the extreme cold

Published on January, 7th 2014
By Dr. Greg Wells

Ray Zahab could be called a little crazy.  And so are his friends.  Which suits me just fine.  Here’s why: in order to study the effects of extreme conditions on the human body, I have to find people who push their bodies to the limit.  Ray fits this requirement perfectly.  So does his close friend Kevin Vallely, who Ray says is “the only person I trust to go on extreme expeditions with.”

IMG_0734_lWhat have these two done that makes them perfect subjects for my research?  A ton.  Like a self-supported, 1,100km speed trek from Hercules Inlet, Antarctica, to the Geographic South Pole in a record time of: 33 days, 23 hours and 55 minutes.

But their cold weather experiences are even more out there – and useful for me as I work to understand how extreme cold can affect our bodies.  In this column, I’d like to share some of the science around exercising in the cold with you.  Especially since the cold can be far more dangerous than the heat.

Consider the situation that Ray and Kevin faced when they trekked unsupported across the frozen Lake Baikal in Siberia.   They each hauled over a 100 lbs of gear in conditions so bad that their Russian coordinator, who was no stranger to the winds coming down off the mountains, told them there was no way they would survive the crossing.

When I talked with Ray about his experience in Siberia, there were several interesting things about how his body adjusted to the conditions.  Dealing with the humidity, dampness, constant exposure to extreme cold and immensely rugged terrain created by pressure cracks in the ice proved quite a challenge.  Ray explained to me that they were not able to melt enough snow or ice to keep hydrated, so they had to adapt to working for hours and hours every day on less than enough water.   They also had to ration their food and discovered that they were able to function on fewer calories at the end of their journey than at the beginning – which includes Ray losing over 20 lbs over the 650 km trek.

Ray’s experiences helped me to further my understanding of the body’s experience of extreme cold and how we need to approach cold-weather activity to ensure we are safe and protected.

Here are a few highlights for you to consider.

Blood Flows to the Core

When you are cold, your body reacts by directing blood to the internal organs in your chest and abdomen.  This can diminish your fine motor control, limit your ability to exert the energy needed for physical activity and increase your risk of frostbite.  Exercise keeps the blood flowing to your extremities so that you keep performing. This can be a benefit as exercise in the cold can me more physiologically demanding, but it also increases risk as blood carries heat from the core and the exercising muscles out the skin where it dissipates into the environment.

Darker Clothing will keep you warmer

Wearing darker clothing in the winter can help to absorb more heat from the sun and make it easier for your body to maintain its ideal temperature range.

Hydration is a major issue in the cold

When it is cold outside, you lose fluids through your breath, skin and sweat.  The cold also has a diuretic effect which causes increased urination.  You need to make sure that you follow the same rules for hydration in the winter that you follow in the summer – between 500 ml and a litre of water per hour even if you don’t feel thirsty.  And if you are exercising for more than 90 minutes, consider a sports drink to ensure you take in electrolytes and glucose.

Hypothermia is a huge risk in the cold

We all know that hypothermia is a problem. And you are more likely to get hypothermia when right after you stop exercising in the cold.  This is because you are no longer producing heat but are still getting wet from sweat.  One of the main reasons that the worst time of year for hypothermia is actually the fall is because people tend not to wear the kind of protective clothing that is typical of winter sports.  No matter what you do, think about wearing clothing that will wick away moisture and keep you dry.  And always have options for extra layers you can put on if you get wet and have a ways to go before you make it back home.

Shivering is a bad sign – take it seriously

Shivering is your body’s response to your core temperature dropping.  Because your body wants to maintain a narrow temperature range inside your body despite the environmental conditions outside, it will signal your muscles to start contracting in short, fast bursts.  These contractions increase energy metabolism to burn fuel and produce heat.  If you are outside and find yourself shivering, you need to get somewhere warm – in a hurry.

The final thing to consider about the cold brings me back to Ray: the body can adapt to almost anything.  Because he has been exposing himself to extreme conditions for such a long period of time, Ray has an extraordinary ability to acclimatize himself to his conditions.  For example, when he ran across the Atacama Desert, Ray was able to train his body to function on only 1.5 L of water a day despite being in 50+ degrees C conditions.

For you, this fact means that you need to take it slow when you start getting out into the cold.  If you give your body time to adjust, it will make physiological changes that will help you handle – and enjoy – the amazing adventures that are to be had when we get outside in the winter months.

-Greg Wells

Read the original article in Get Out There Magazine by clicking here.