When running in cold weather, one must consider the combination of wind and temperature. This is known as the effective temperature, or wind chill index, which is the combined effect of temperature and air movements on the body surface. The wind makes a tremendous difference in comfort and at what temperature the exposed human flesh will begin to freeze.
There is real danger with frostbite of the feet when running shoes get wet. Sixty-five percent of your body weight is made up of fluids, which are found in and around your cells, and circulate through your body as blood and lymph.
When the temperature of your body drops below freezing, ice crystals form in the fluid around your cells. As a result, the cells are damaged. The signs of frostbite are easy to recognize with skin temperature dropping. The blood vessels close up and less blood flows through.
As a result, your skin turns white. When your skin temperature reaches 59 degrees, your body attempts to re-warm the skin by opening the blood vessels and increasing circulation to the surface. Your skin will begin to feel warm, tingly and turn red. However, with a further drop in temperature, the blood vessels begin to close up again. If the skin is allowed to freeze, it will be white in appearance and feel hard to the touch. If frostbite is suspected, get indoors immediately and seek medical attention if necessary.
Cold weather can create other problems such as hypothermia (below normal body temperature), slippery footing and influenza. Many people are afraid to run in the cold because of the myths of developing frozen lungs or having a heart attack. After reviewing literature on the subject of frozen lungs, I could not find any reports of cold air damaging a person's lungs during cold weather exercise.
This is probably due to the fact that air is automatically warmed before it reaches your lungs. Be especially cautious, however, if you have cold weather/exercise induced asthma. You'll need to take the proper precautions to avoid breathing in all that cold air. It is advisable to eat more as extra fuel is needed to run in the cold. Carbohydrates and fat are the primary source of energy; therefore, it is important to eat more fruits, nuts, bread, cereal, pancakes and pasta.
Dressing properly for cold weather runs is most important. The layered method is most efficient as air is trapped between each layer creating insulation. A gortex jacket is an excellent top layer as it is lined with a waterproof, breathable fabric that allows water vapor to escape, but prevents moisture from getting in.