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Family Health Magazine
ACTIVE LIVING

Exercising in the Cold
Keep fit this winter - safely

Every year, Canadians look forward to the cold weather with a mixture of anticipation and apprehension. Shoveling, commuting and routine errands make it impossible to avoid the outdoors altogether. Indeed, physical activities like skating, skiing and snow shoeing can make the cold a pleasure. Whatever may bring you outdoors, there are precautions you can take to make sure your time spent outside is safe and enjoyable.

Frostbite

Frostbite happens when fluids or tissue in or under the skin crystallize after exposure to sub-freezing temperature. It can occur within seconds or hours of cold exposure, depending on air temperature, wind speed and body insulation. The most susceptible parts of the body include the ears, fingers and toes. Frostbitten skin can look white, yellow-white or purple, and is hard, cold and numb to the touch. Rewarming results in intense pain, skin reddening and swelling. The amount of tissue damage depends on the duration and severity of cold exposure.

You can take steps to avoid frostbite. Protect exposed areas with appropriate clothing. Keep feet warm and dry by wearing proper socks (double layer with an inner polypropylene and outer wool, if necessary) and waterproof boots. Protect hands with mittens. Cover your head, face and ears with a hat, scarf or balaclava.

Hypothermia

Hypothermia occurs when the body’s core temperature falls below 36°C and the body loses heat faster than its metabolism can produce it. Early symptoms of hypothermia include shivering, euphoria (an intense sense of well being) or confusion. Later signs include lethargy, muscle weakness, disorientation, hallucinations, depression or aggressive behaviour. If body core temperature falls below 31.1°C, shivering may stop, delirium increases, co-ordination decreases and eventually coma sets in.

Women and children are at a higher risk for cold injury because in general they have less muscle mass per body surface area and so lose heat more quickly.

The most important way to prevent hypothermia is to be properly dressed. Wearing appropriate layers creates your own ‘mini-environment’, improving insulation of your body by acting as a barrier against the cold. A three-layer system is effective for most cold-weather exercise.

Inner layer:This layer is worn next to your skin and should be lightweight, snug-fitting and able to wick (draw away from the skin) perspiration. Use undershirts and leggings made of synthetics such as polypropylene or acrylic.

Middle layer: This insulation layer should wick moisture and provide warmth by trapping air. Use lightweight synthetics such as polyester fleece and therma fleece.

Outer layer: This protective layer shields you from wind, rain or snow. A light nylon jacket may suffice or you may want a synthetic such as Gortex™ that allows moisture to release while providing wind and water protection. Zippered garments have the advantage of letting you unzip as much as you want for comfort.

Remember that up to 40 percent of body heat can be lost through your head. Your ears, fingers and toes are also at risk for cold injury because their blood vessels become smaller when exposed to the cold. Protect your head with a hat, tuque or balaclava and wear gloves, warm socks and boots.

Heart Disease

Exercising in the cold puts extra stress on the heart, especially if you are not used to exercising. As a result, those with heart disease are less able to tolerate exercising in the cold, and are more at risk to develop angina (heart or chest pain), heart attacks and irregular heartbeat. People with heart disease or who are inactive should restrict themselves to low-intensity activities like walking. They should avoid strenuous activities in the cold including seemingly safe things like shoveling the sidewalk. Be aware of the symptoms of angina and heart attack. If you notice signs in yourself or others, don’t wait. Call emergency medical services (911) right away.

Asthma

For those with asthma, the combination of exercise and breathing in cold dry air can often make asthma symptoms harder to control. For those who have not previously been diagnosed with asthma, symptoms of exercise-induced broncho-constriction (EIB) may become more apparent. Symptoms of EIB include coughing, wheezing or difficulty breathing starting five to 15 minutes after cold exposure or exercise. Symptoms may persist for several hours. If you experience this pattern of symptoms, talk to your doctor.

Medications are available which can be inhaled before exercise or exposure to cold air to prevent or cut down constriction and inflammation of the airways. You can also reduce the effect of cold air by wearing a scarf over your nose and mouth or using a mask to warm the air before it reaches your airways.

Muscle Injury

When you exercise in the cold, your muscles tend to cool down. As a result, they are less efficient and have to work harder than normal. This requires your cardiovascular system to also work harder and you may tire more easily. Older adults and inactive people have less muscular and cardiac reserve and must be careful not to overexert themselves. Everyone should expect to tire more quickly when exercising in cold weather.

Once muscle is cold, it is difficult to rewarm. However, exercise prevents warm muscles from cooling down even in cold weather. If you are planning to exercise in the cold, do a brief five to 10 minute warm-up inside or start exercising as soon as you go outdoors. The key is not to allow muscles to get cold in the first place.

Dehydration

Although it may not seem likely, dehydration is a concern during cold-weather exercise and increases the risk of frostbite and hypothermia. While exercising in the cold, you can become dehydrated for a variety or reasons. These include increased urine production caused by the cold, water vapour loss as you breathe, sweating and less fluid intake.

Pay attention to the amount of fluid you are drinking, and always have drinks handy while you are exercising. You should be drinking 500 mL of fluid up to two hours before exercise. Once you begin to exercise, drink 150 to 250 mL every 10 to 15 minutes to balance the amount you are losing. Remember that thirst is not a good indicator of how much liquid you need – drinking to satisfy thirst replaces only half of what is lost through sweat. Avoid drinking caffeine or alcohol as they will actually increase fluid loss rather than keeping liquid in your system.

Being aware of risks and taking precautions when exercising in the cold will allow you to enjoy all of your favourite cold-weather activities – safely.