Of course, if you find cold-weather exercise aversive, you can always substitute walking through shopping malls, or running indoors on a treadmill. Stationary cycles, stairclimbers, rowers, and cross-country ski machines provide a variety of training alternatives for those who prefer to exercise in shorts and tee-shirts.

However, if you comply with a few basic training recommendations, you should be able to enjoy outdoor walking and running on all but the coldest winter days. But first, let's examine some misconceptions about cold-weather exercise that might otherwise limit your training sessions.

1. Breathing colder air does not freeze your lungs. In fact, by the time inhaled air reaches your lung exchange areas it is approximately body temperature. It is therefore not necessary nor recommended to wear scarves or handkerchiefs over your mouth/nose when walking or running.

2. Exercising in colder weather does not adversely affect your muscles, nor compromise normal walking and running movement patterns. Although sprint workouts are not advisable, you need not slow your standard training pace due to lower temperatures. Also, it is not necessary to reduce your normal training time/distance under most winter conditions.

3. Exercising in lower temperatures does not require several layers of clothing to maintain body warmth. A pair of sweatpants and a hooded sweatshirt should be sufficient for temperatures above 20¡ F. Actually, wearing too much clothing can result in excessive heat accumulation and perspiration, both of which can have detrimental physical consequences.

So how should you prepare for winter runs and walks? Start with the assumption that the temperature is about 10¡ warmer than it really is. This accounts for the extra heat you will produce as you begin to exercise. Of course the more vigorous the activity, the more body heat you will generate.

Keep in mind also, that your legs and trunk tend to stay warmer than your hands and head. A pair of gloves, mittens, or socks over your hands can make a big difference in your comfort level, as can a headband, stocking hat or hooded sweatshirt. Usually, a single pair of athletic socks is sufficient, as your feet benefit from frictional heat during walking and running. The choice between tights and sweatpants is largely a matter of personal preference. As temperatures decrease, I recommend the following progression of upper body attire.

Above 50¡ F Short sleeve tee shirt.
40¡ -50¡ F Long sleeve tee shirt.
30¡ - 40¡ F Short sleeve tee shirt and sweatshirt.
20¡ - 30¡ F Long sleeve tee shirt and sweatshirt.
Under 20¡ F Short sleeve tee shirt and long sleeve tee shirt and sweatshirt.

A good warm-up inside the house typically makes your first few minutes of outdoor activity more enjoyable on cold days. Several minutes of calisthenic exercises such as trunk curls, push-ups, knee-bends, and step-ups can increase your body temperature considerably.

If you are sensitive to breathing cold air, try to inhale through both your mouth and nose. Although nose breathing has a greater air-warming effect, most people can not get enough air through the nose alone to sustain fast walking or running. Breathing through both channels should ensure enough oxygen for exercise as well as warmer air temperature. By the way, keeping yourself well hydrated is helpful in this regard and for optimum physical performance. Proper fluid intake is no less important for winter exercise sessions than any other season. Be sure to drink ample water or fruit juices before and after your cold-weather workouts.

Assuming you are properly prepared, and neither overdressed or underdressed, your walking/running form and pace should be little different than during the rest of the year. However, when you finish your workout you should transition immediately into your cooldown activity and go inside for your concluding stretches. Standing around wet with perspiration in cold temperatures is not advisable, as this can result in quick cooling and tightening of your muscles.

In summary, an appropriate winter running workout may be approached as follows.

1. Check the weather conditions and temperature and dress appropriately. However, if the sidewalks/roadways are icy or slippery with snow, postpone your exercise session until they are clear.

2. Perform four to eight minutes of warm-up activity for your legs (e.g., knee bends), midsection (e.g., trunk curls), and upper body (e.g., push-ups).

3. Step outside and promptly begin your walk or run. Start slowly, and progressively increase your pace to the target intensity.

4. As you finish your training session, slow down gradually and continue with four to eight minutes of cooldown activity.

5. Without stopping, go indoors and finish your workout with a few stretching exercises.

Note: Be sure to drink sufficient fluids before and after your training session.

Of course, you may always choose to exercise indoors on uncomfortably cold days. But, if you prefer the fresh air of the great outdoors, these guidelines should be useful.

Wayne L. Westcott, Ph.D., is fitness research director at the South Shore YMCA in Quincy, MA., and author of several fitness books including the new releases, Building Strength and Stamina and Strength Training Past 50.