By Andrew Niemann, ATC and Susan Yeargin, PhD, ATC
Spending time outdoors is fun, even in the cold of winter, but require special precautions to avoid dehydration, hypothermia, and frostbite. Here are some things to consider if you or your children plan to spend some quality time outdoors in the cold this winter.
Dehydration and cold exposure
When spending time outdoors in winter, the body adapts to the cold and dry ambient air by trying to retain heat. In an attempt to maintain core temperature, the amount of warm blood the body sends to the arms and legs is decreased in order to reduce the amount of body heat lost to the cold air. By decreasing the amount of blood to the extremities, more warm blood stays in the core region of the body. This eventually leads to the kidneys producing more urine. When this cold-induced increase in urine production occurs, over time it can lead to dehydration. The body also is more prone to dehydration because breathing cold, dry air results in fluid loss through evaporation.
To prevent dehydration during cold weather exercise, you and your child should:
- Expect more frequent bathroom breaks, particularly at first;
- Make sure to bring fluids (water, sports drink, juice, etc.) with you to stay hydrated;
- Cover your nose and mouth to minimize fluid losses from breathing;
- Have fluids (room temperature or or warm) ready to drink when you come inside after exercise.
Hypothermia occurs when the body experiences a decrease in core temperature. There are varying severities of hypothermia, the cooler the core body temperature the more severe the hypothermia. Prolonged exposure to cool, wet, windy environmental conditions increases the likelihood of hypothermia.
Surprisingly, hypothermia can occur even in cool weather (up to 50º F) . When spending time outdoors in colder weather, the body generates heat to maintain core body temperature in two ways: through exercise and by shivering, which is the primary mechanism the body uses to generate heat. Shivering intensity is determined by the severity and duration of cold exposure and generally occurs in the large muscles of the trunk first.
How do you recognize the onset of hypothermia? Look for signs of the "umbles":
- Grumbling (personality change);
- Mumbling (having a hard time articulating words);
- Stumbling (reduced coordination in the arms and legs); and
- Fumbling (decreased dexterity).
To prevent hypothermia, you and your child should:
- Wear a hat . The most significant loss of body heat is from the head and the body has no way to minimize heat loss in this region of the body.
- Layer clothing. Wear warm but breathable layers of clothing to stay warm
- Pay attention to shivering. Shivering is a good thing because it produces body heat, but if it reaches severe levels, stop exercising and head indoors.
- Keep up the pace. Keep your exercise intensity in the cold at moderate to high intensity to help maintain core body temperature. In order to maintain this intensity, take numerous breaks if needed
- Bring extra clothing. If you are exercising in a relatively remote area (such as on a long cross-country skiing excursion) bring an extra set of dry clothes with you.
Frostbite occurs when there is actual freezing of body tissue. Just as in hypothermia, there are varying levels of frostbite severity; the deeper and more extensive the tissue damage, the more severe the frostbite. The extremities furthest from the core of the body (toes, nose, fingers, etc) are the most sensitive areas to local temperature change and blood vessel constriction. These distant extremities are not able to sense whether the body's core temperature is adequate or not. This means that even if the core is at an adequate temperature, the blood vessels that supply these cold extremities continue to redirect blood to the core no matter what. This absence of warm blood locally leads to temperature loss in the extremities, which could eventually freeze the tissue, resulting in frostbite.
Common signs and symptoms of frostnip and mild frostbite are:
- Aching, tingling or burning pain that eventually progresses to decreased sensation or numbness (body part is often described as feeling "wooden")
- Very red or mottled grey skin of the body part
- Mild swelling or edema of the body part
To prevent frostbite, you and your child should:
- Wear gloves and warm socks
- Cover the face
- Bring an extra pair of gloves and socks in case the ones you are wearing get damp or wet
- Check the fingers, toes, and nose every so often for signs of frost nip and frostbite
- Keep your fingers and toes involved in exercise/moving
- Take frequent breaks or stay indoors if the wind chill is too severe
Special considerations for children
Research has shown that, due to a higher surface area to mass ratio and smaller amounts of insulating adipose fat, children lose body heat more quickly than adults. While the same precautions should be taken for children as for adults, children should take more frequent breaks from exposure to the cold.
Dehydration as a risk factor for hypothermia and frostbite
As discussed above, dehydration can occur when exercising or playing in cold air. Research has shown, however, that dehydration does not affect the body's ability to produce and conserve heat. Essentially, to the body, maintaining core temperature is more important than maintaining fluid balance. Therefore, dehydration is not necessarily a risk factor for hypothermia and frostbite, but more of a symptom of exposure to the cold. This does not mean that maintaining proper hydration is not important. Steps to ensure proper hydration should still be taken, especially since the thirst mechanism is suppressed during exposure to the cold.
1. Cappaert TA, Stone JA, Castellani JW, Krause BA, Smith D, Stephens BA. National Athletic Trainers' Association Position Statement: Environmental Cold injuries. J Athletic Training. Oct-Dec 2008; 43(6): 640-658.
2. Castellani JW, Young AJ, Ducharme MB, Giesbrecht GG, Glickman E, Sallis RE. American College of Sports Medicine Position Stand: Prevention of Cold Injuries During Exercise. Med Sci Sports Exercise. Nov 2006; 38(11): 2012-2029Posted January 6, 2011; revised October 31, 2011