NEW YORK (MainStreet) — Americans love to run. (Don't call it "jogging" — purists consider the term way too pedestrian — literally.) Running USA estimates that 6.2 million Americans at least finished a five-kilometer race in 2012, and more than 15 million Americans finished a running race of some duration that year.

That's an 80% rise in the number of U.S. "roadrunners" since 2000, as more and more adults see running as a safe, enjoyable way to lose weight, stay healthy and clear their mind for the busy day or night ahead.

Running USA says the number of runners has risen every year for the past 20, save for one year — 2003 — and that the trend should continue in the years ahead.

That's a good sign for the health of the nation, but with the cold snaps this month it's worth asking: Is it a good idea to layer up and hit the road when the temperature falls below 32 degrees?

"Some people find they run better in cold weather conditions," says Dr. Paul Langer, a podiatrist with Minneapolis' Twin Cities Orthopedics. "I have set most of my personal records in spring races."

"The only thing that keeps me from running outdoors in winter is ice," Langer says. "I have seen too many walkers and runners with ankle fractures when it is icy out."

Langer cites the annual Securian Winter Run, a bellwether event in Minneapolis-St. Paul's annual January carnival, which historically has drawn big crowds even as the barometer reads 25 degrees or so. It's OK to run in those conditions, Langer says, but caution should be taken before running in freezing weather:

Watch for ice. Running early in the day or late at night can result in broken bones and pulled muscles from careening on ice. To get a grip, run in the middle of the day. Better yet, join a gym and run indoors on sub-freezing days.

Take care of your lower body. Many runners report lower body injuries, especially injuries to the foot, ankle or knee. Those runners need to take heed. "The cold can exacerbate overuse injuries," Langer says. "I advise patients with knee or ankle issues to keep their lower extremities insulated in winter." Extra socks and more layers are the best way to warm up down below, he says.

Buy winter running shoes. To further fight wind, ice, snow and water, switch to deeper-soled winter running shoes. Such footwear has wind- and water-resistant uppers and more aggressive outsoles, which excel in wintry conditions, Langer says.