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Baby it's Cold Outside!

Cold weather exertion and the heart

While working out in cold weather, it’s important to try and avoid sweating. Wearing appropriate clothing allows you to put on or take off layers as your body’s needs suggest.

While working out in cold weather, it’s important to try and avoid sweating. Wearing appropriate clothing allows you to put on or take off layers as your body’s needs suggest.

Well, possibly. But the fact is, cold weather exertion brings with it a unique set of circumstances that affects the body, and the more we know about what happens when we work out in the cold, the better equipped we’ll be to do it safely.

Dr. Pamela Taylor, Medical Director of Cardiology at Saint Francis Medical Center, says, “When we exercise in the warm weather, our blood vessels dilate, especially those in the skin, to help us dissipate the heat generated by muscular contraction. In the winter, our body instead tries to conserve its heat by keeping the warm blood directed to our body’s core. The peripheral small blood vessels constrict, rather than dilating, to shunt blood away from our skin where it would get cold. Because of this, blood pressure increases relatively more with cold weather exercise than with warm weather exercise. Fingers, toes and skin get cold due to limited circulation to those parts.”

So let’s say you’re an early riser. You jump out of bed at the first hint of sunrise, throw back a few sips of coffee or tea, put on your favorite cotton turtleneck and running tights and head outside for a run. Partway through your route, your chest begins to hurt a little. You decide to power through it, hoping the pain goes away.

You’ve just made several mistakes, unwittingly putting the good health you’ve worked so hard to achieve in peril.
“Running, when set up correctly, can be good to do with appropriate precautions, especially if you warm up,” says Pikes Peak Cardiology physician David Greenberg. “But if you suddenly just go out in the cold with no warm up and start, say, lifting heavy objects, it will cause a sudden increase in demand with a total inability of the heart to increase the blood supply to all the tissues that need that blood flow.” Dr. Greenberg says in such a situation, there will likely be some compromise to vital internal organs, especially the heart.

“Increased blood pressure,” says Greenberg, “causes increased workload on the heart so it works harder and faster, increasing heart demands. There is also an increase in the thickening of the blood to a moderate degree, secondary to the colder temperatures. Add to that the effects of heat loss and hypothermia and this can be a vicious cycle.”

Let’s add a little pre-existing high blood pressure to our scenario, and let’s say you’re already taking high blood pressure meds. “Many blood pressure medications alter our body’s natural adaption to both cold weather and to exercise,” says Dr. Taylor. “Warming up by gradually moving, and pre-hydrating before exercise are two behaviors that are beneficial.”

And of course we must take into consideration high altitude exercise. “Many aspects of being at high altitude come into play when we exercise in the winter,” says Dr. Taylor. “Less oxygen, of course, is more taxing to our bodies. We need to breathe faster and deeper to provide enough oxygen to nourish our muscles. This hyperventilation causes dehydration as we lose moisture with every breath. It’s colder at higher altitude and the risks of hypothermia increase.”
And last but certainly not least, remember that favorite cotton turtleneck you chose for your run? Not a good idea, cotton, since when the comfy fabric gets wet, it stays wet.

“Wet clothes accelerate heat loss 25-fold as compared to dry clothes,” says Taylor. “The body simply can’t keep up enough heat generation to warm itself, despite shivering. This is hypothermia. Perspiration-soaked clothes, even the ‘wicking layer’ we all put on first, cause drastic loss of body heat that few athletes can recover from, except by removing the cold wet clothes and putting on some warm dry ones.”

Dr. Greenberg offers several simple tips for safe cold-weather exercise:
• Layer up – inside layer of polypro for wicking, middle layer of fleece for warmth, outer layer of lighter-weight water-proofing.
• Wear hats, and masks for better and warmer breathing.
• Warm up slowly to increase blood flow to the arms and legs.
• Run into the wind first, then run with the wind at your back as you finish.
• If you’re shoveling snow, take a break after 10-15 minutes.
• If the wind chill is less than zero, run inside.