Winter environmental conditions often provide a significant challenge for people to maintain a consistent physical activity program. Cold temperatures, wind, and precipitation can easily discourage even the most motivated exerciser, and for those not so highly inclined, it is far too easy to take an exercise vacation for a few months. Moving exercise sessions indoors on inclement weather days and using either home exercise equipment or a local fitness center is an excellent option. However, with the right preparation and precautions, outdoor activities can safely and enjoyably continue throughout most of the winter season.
The normal resting body temperature is generally considered to be 98.6°F (37°C). We are uniquely designed with various feedback and hormonal systems to maintain our internal body temperature within a fairly narrow range of 96.8°F to 100.4°F (36°C to 38°C). Our body is naturally insulated by skin, muscle, and fat. At rest, a lesser amount of these natural insulators may be an advantage for the lean individual in hot weather, whereas the more insulated individual may be at a slight advantage under cold conditions. Muscle mass is an important component in temperature regulation, serving not only as an insulator but also as a heat producer during physical activity.
Core temperature is maintained via sensory information interpreted by the preoptic anterior hypothalamus or the brain’s control center for temperature regulation. When exposed to cold, a number of progressive and protective adaptations occur that serve to maintain a person’s core temperature. Some of these responses to cold include:
- Vasoconstriction of the small arteries or arterioles serves to shunt warm blood away from the peripheral tissues to the core.
- Nonshivering thermogenesis or a slight increase in metabolic rate that increases heat production.
- Shivering or low-grade and rapid involuntary cycles of muscle contraction and relaxation can increase heat production threefold to sixfold.
- Stimulation of movement or exercise that can increase heat production 20- to 25-fold.
Two potential hazards of cold weather exposure are hypothermia and frostbite. Hypothermia results when the body loses heat faster than it can produce it, resulting in a gradual decline in core temperature. Wet clothing, cold temperatures, and wind increase the risk of hypothermia, defined as a drop in core temperature of 2°C or more, especially when a person becomes fatigued and dehydrated. Frostbite occurs when body tissues are exposed to temperatures below the freezing point of the skin. Areas of the body that are the farthest away from the heart, such as the nose, cheeks, ears, fingers, and toes are particularly susceptible. Frostbite may be more common in recreational athletes than hypothermia and is characterized by white or grayish-yellow skin that is very cold and may have a waxy feel. Both conditions are preventable; however, without proper and immediate attention could result in loss of tissue, limbs, and even death.
Almost everyone can exercise safely in cold weather with appropriate preparation. People with chronic health conditions such as heart disease and asthma should check with their physician before exercising in cold weather. The following tips will help make the winter workout more enjoyable:
- Dress in layers so clothing can be removed to prevent overheating and excessive sweating.
- ○ Use an inner layer that consists of a treated polyester-type material such as polypropylene, cool max, or DryLite that will wick water away from the skin. Avoid using cotton next to the skin.
- ○ Fleece or wool serves as a good insulating middle layer.
- ○ Wear a waterproof yet breathable outer layer that will repel the wind.
- Protect hands, feet, and ears.
- ○ Waterproof gloves or mittens that are lined with fleece or wool.
- ○ Thermal socks, consider using a shoe 0.5 size larger than normal to accommodate heavier insulated socks.
- Face the wind first, so it is at your back when you head home; under extreme wind chill, move indoors.
- Stay hydrated. Dehydration increases the risk of an adverse event occurring even in cold conditions.
- Know the signs of frostbite and hypothermia, and move indoors to finish or discontinue the exercise session should they occur.