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San Francisco 49ers running back Frank Gore (21) gets tackled by Green Bay Packers cornerback Micah Hyde (33) during the first half of an NFL wild-card playoff football game, Sunday, Jan. 5, 2014, in Green Bay, Wis.

San Francisco 49ers running back Frank Gore gets tackled by Green Bay Packers cornerback Micah Hyde during a game on January 5, 2014, in Green Bay, Wisconsin.

PHOTOGRAPH BY JEFFREY PHELPS/AP  

Christine Dell'Amore

National Geographic

Published January 7, 2014

Thinking of taking a jog in the coldest weather to hit the U.S. in decades? You may want to read this.

Subzero temperatures can do a number on your body in short order. According to experts, a wind chill of -50°F (-45°C)—the current conditions in parts of the central Appalachians—can cause frostbite in five minutes.

Born of a polar vortex—a whirlpool of air chilled in northern Canada, now being blown south into the U.S.—the bitter temperatures are, luckily, not expected to last beyond Wednesday. (Related: "Behind Record U.S. Cold Snap: Canadian Air and a Jet Stream Kink.")

But in the meantime, experts say, Americans—even professional athletes—should take this cold snap seriously.

We talked to Henderson McGinnis, a wilderness medicine expert and emergency physician at North Carolina's Wake Forest Baptist Medical Center, and Michael Lanigan, an attending physician in the Department of Emergency Medicine at SUNY Downstate Medical Center in New York City, about how the body responds to such frigid weather—and how best to handle it.

What happens to the body in extreme cold?

Our bodies are built to protect their most precious machinery—vital organs such as the heart, kidneys, and lungs. When faced with bone-chilling cold, we shunt all available blood to these organs to keep them warm and functioning. That means that "extremities take the hit for the rest of the body," said Lanigan, which is why your fingertips, toes, nose, and earlobes get so cold: They lose their blood. (Watch a video: "Human Body 101.")

It's also why you may feel like urinating when you're in very cold weather: Your kidneys get a lot of blood flow. (Though "the last thing you think about doing [in the cold] is peeing outside," quipped McGinnis.)

Reduced blood flow to the extremities makes your legs and arms more sluggish. If you're out long enough and your body temperature starts to drop, your metabolism—how your body processes energy—also slows, causing mental confusion.

There's a saying that "cold makes you dumb," McGinnis said—meaning it's particularly dangerous if you have to make a crucial decision in the cold, like choosing a path on a hiking trail.

If skin is exposed for too long, frostbite—or skin damage caused by cold—can eventually set in. Whether someone gets frostbite depends on several variables, such as the person's health, the temperature, and the length of exposure.

How dangerous is it to be in extreme cold?

Prolonged exposure to severe cold is "a real risk," McGinnis said, though there's no real definition for "prolonged." Indeed, little is really known about how much cold is too much cold; doctors don't experiment on people because it would be inhumane.

Much of how you fare depends on your health and age: A healthy, well-prepared person in bitter cold for a few minutes will likely be OK. (See pictures of National Geographic explorers who have battled frigid extremes.)

Another factor to consider is the wind, which robs your body of heat more quickly than it can be produced. That's why biking or running in very low temperatures—which increases a person's pace and exposes them to more wind—is a bit more dangerous than walking, McGinnis said.

What's more, "it doesn't have to be a super-freezing or Mount Everest-type environment" to see the effects of cold if someone is outside long enough. As McGinnis noted, "We see people in North Carolina who have frostbite."

Lanigan added that his hospital in New York has already received some frostbite patients due to the cold snap.

What about professional athletes—especially football players who play in the brutal cold?

Playing football in temperatures below 20°F (-7°C) "is not smart," said McGinnis, "but it's not any more dangerous than getting hit by a linebacker."

But when you get into subzero temperatures, he said, it becomes foolhardy. The San Francisco 49ers beat the Green Bay Packers in Wisconsin on Sunday when the windchill was -10°F (-23°C)—one of the coldest games in NFL history.

Many players even wore short sleeves, which McGinnis called a "a macho thing" to psych the other team out. (Though "it didn't work in Green Bay," he quipped, "since [the Packers] lost.")

Most players were prepared for the cold, though, wearing gloves and using hand-warmers and covering their skin when they were off the field. Plus, said Lanigan, wearing short sleeves isn't quite as bad as wearing short pants, since the players' upper limbs are closer to their hearts and thus a bit warmer.

In general, athletes—even though they're in superb shape—may encounter additional effects from the cold because their constant motion forces blood to the extremities, taking the vital fluid away from the organs.

Exposing muscles to extreme cold also increases the likelihood of tears, sprains, and spasms.

What's your advice to people for weathering this cold snap?

First off, avoid being outside for prolonged periods. If you're going to be outside for a long time, cover up exposed skin—especially the face—and eat and drink water beforehand: Eating provides your body with fuel that can help you tolerate cold. Also, wear a windbreaker to prevent frigid gusts from stealing your body's heat.

If you start to feel pain or numbness, or notice your skin turning paler, go inside immediately: These may be early signs of frostbite. (And whatever you do, says McGinnis, don't rub the affected skin—that increases the damage.)

Perhaps the most important piece of advice? Always have someone else with you, says McGinnis, or at least tell someone where you're going. "Don't be Aron Ralston," the rock climber who kept his travel plans to himself, got stuck under a boulder in Utah, and had to cut off his arm with a pocketknife.

In other words, says McGinnis, "use common sense."

Follow Christine Dell'Amore on Twitter and Google+.

4 comments
Mark Berry
Mark Berry

Quote "Many players even wore short sleeves, which McGinnis called a "a macho thing" to psych the other team out." -- not always the case.

Going without sleeves has been a proven strategy (although not so much in that game maybe) to being able to grip a slippier and harder football in colder conditions.


Jeez, with the attitude of this article it's amazing we have a winter olympics! :)

Kristianna Thomas
Kristianna Thomas

They say that its cold in them there hills.  From Bear Mountain to the coal fields of West Virginia has become an ice box of the North, but what of the frozen North of Canada and Alaska?  We here in the lower forty are used to milder climates that don't dip in the Alaskan / Siberian range.  Forty and fifty below is average for Siberia and Alaska, and they have been doing so for generations.  This information is useful and like the author states, "use common sense."  But!  If common sense was truly common, everyone would have it.

carlos gomes
carlos gomes

once i was convinced portugal had one of the most fair pathern of weather on the entire solar sistem.                                                                                                                                        now we need some extra-terrestrial advice.                                                                                  gaia were are you? 

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