My skin was chapped, my hands blue, my face a raging red.

I had come in from running in the cold and was chilled by the realization that it was not the same experience as running in the warmth of the sun.

The problem with running in cold weather is that you keep thinking it should be easier than running in the heat. But really, cold weather presents an abundance of medical and non-medical concerns that runners should be prepared to face.

Medical Concerns: Lung congestion and muscle strains are among the more minor medical problems running in the cold can cause, while increased stress on the heart is a major concern.

Running in any weather causes stress on the windpipe and stretches the tissue surrounding it, according to Dr. Robert Nirschl, an orthopedic surgeon and one of the nation's leading experts in sports medicine. Cold air seems to increase the amount of stress which often causes temporary wheezing, coughing and congestion even in runners who never experience these problems in warm weather.

Nirschl notes that these problems are rarely long-lasting, but he says they can be diminished or eliminated altogether by wearing a thin covering like a scarf or surgical covering over the mouth. "This will allow the runner to move air, but break the chill first," Nirschl says. Since moisture will form on the covering, Nirschl advises runners to carry a replacement or two.

Muscle strains, the most common cold-weather ailment of runners, often are caused by the runner's failure to distinguish between warm-up and flexibility exercising.

"I see runners go out in cold weather and the first thing they do is start stretching or pushing against a tree to loosen up," Nirschl says. "But there's lard inside our muscles that gels in the cold. If we strain before the lard is warmed up properly, the muscle must fight the gel, which causes friction." The result can be muscle soreness, strains or pulls.

Prior to attempting stretching and other flexibility exercises, Nirschl suggests warming up by running easily until breaking a light sweat. "By then the lard is liquidified substantially to eliminate friction," Nirschl says. "Then you can go on to flexibility exercises and harder running."

Runners should make an effort not to alter their running style by shifting body weight or changing movements to accommodate a chill. Such changes can result in assorted aches and pains.

"By changing running patterns, you change the force loads in a way the body is unaccustomed to," Nirschl explained. "You may, in effect, wind up asking different, less-prepared body parts to handle the loads and that subjects you to strains.

Since cold weather increases the overall amount of stress on the body, it can cause increased stress on the cardiovascular system. Running too hard in the cold weather without adequate warmup can prove dangerous to the heart.

"If the heart is pressured suddenly because the body is not heated up," Nirschl says, "it causes extra friction. This may cause the chemical system in the body to change suddenly. A very large swing (in the chemical structure) can cause disrhythmia -- a malfunction in the heart's rhythm."

Dishythmia, characterized by the heart missing beats or running beats together, can lead to cardiac arrest.

Nirschl urges cold-weather runners to remember that "warming up takes longer than in warm weather."

A warm-up may save you aches, pains and years of your life.

Non-medical Concerns: Judi Greenhalgh of Reston has been running year round since 1969. Several marathons, including four Marine Corps and one Boston, have passed under the soles of her running shoes and she currently acts as adviser and trainer of the Reston Runners. She offers the following advice on how to prepare for the discomforts of running in the cold.

Never overdress -- "If you do, you become overheated and you don't go the distance. Then you're defeating your purpose."

Greenhalgh suggest dressing in layers -- a T-shirt, thin turtleneck or scarf and a nylon windbreaker. For the legs, Greenhalgh recommends either tights or cotton sweat pants covered with gym shorts.

"When you feel your body temperature increasing remove some of the clothing." Greenhalgh says. The best way to carry removed clothing is to simply tie it around your waist.

Cover your head -- Greenhalgh suggests thin stocking-type hats that can be pulled down over your ears, which tend to get exposed and cold in the wind. Also, about 25 percent of your body heat can escape from an uncovered head, so a cap will wind up keeping more than your head warm.

Cover your hands -- Exposed fingers get chilled easily, but wearing gloves or mittens often causes perspiration to build up in the palms. Greenhalgh says socks are the most effective and comfortable hand-warmers since they keep the hands warm but allow some air and absorb perspiration.

Protect your skin -- Cold weather causes dryness to areas exposed to the weather and to areas supposedly protected from it. Applying Vaseline or chapstick to areas around the nose, eyes and lips before, during and after a run can prevent chafing and wind burn. Apply some body lotion after showering.

Protect your eyes -- The cold, Greenhalgh warns, can dry out a runner's eyes, causing a burning sensation. Sunglass provide the best protection.

Beware of wind-chill factor -- When it drops to 20 below or less, you might think about staying by the fire. "That's when you can really feel it," says Greenhalgh, who will trek through snow ("the greatest sight in the world") and ice ("you just have to learn how").