Exercise can be performed at very low temperatures and even well below 0°C (32°F) in well prepared and appropriately dressed healthy individuals. The risk of injury, such as hypothermia (decreased core body temperature) and frostbite (freezing injury of the extremities), is real yet preventable with appropriate clothing and avoidance of circumstances that put you at high risk, such as wind and moisture.
Several factors that change the risk of cold weather injuries are:
- Preparedness such as appropriate clothing choices, hydration and food intake, all of which can vary the risk of cold injuries.
- Environmental factors. Wind and moisture (from rain or snow) will certainly increase the risk of cold weather injury.
- Individual Characteristics. For example, older adults, children and people who have health issues such as asthma and heart disease are at greater risk for cold weather injuries.
Clothing recommendations for preventing cold injuries while exercising
Exercise is an excellent countermeasure to prevent hypothermia, although in very cold temperatures the ‘exercising body’ is susceptible to hypothermia and frostbite. Even if the temperatures are not cold enough for frostbite there are clothing recommendations to staying comfortable and warm even in moderately cold temperatures, especially on wet and windy days. The role of clothing in preventing cold injuries lies in its ability to reduce heat loss to the environment by trapping warm air next to the body. For the best results to stay comfortable and warm three layers are advised. This reduces heat loss to the environment by trapping warm air next to the body. These layers are:
- an internal layer that allows evaporation of sweat from the skin while exercising without absorption. The internal layer should be in direct contact with the skin and be a moisture-wicking material such as polyester or polypropylene. As a result, this layer transfers the moisture to outer layers, from which it can evaporate.
- a middle layer that provides insulation. The middle layer provides the primary insulation against heat loss and can be a fleece or wool material.
- an external layer that is wind and water resistant, and that also allows evaporation of moisture. The outer layer should have venting abilities (eg, zippers or mesh in the armpits or low back area) to allow moisture transfer to the environment.
Avoid cotton clothing, as this material doesn’t hold body heat as well as wool or polypropylene. It’s also important to wear a cap or hat and gloves when exercising in the extreme cold. Heat losses from the head have been measured up to 50% of the total resting heat production in a person sitting in −4°C (25°F) air while wearing winter clothing. Caps and balaclavas can decrease this heat loss substantially. Headbands can also be used to cover the ears but allow for heat loss through the head. Socks should not be tightly fitting to avoid constricting blood flow to the lower leg and feet. Shoes can be ½ to one size larger with thick socks.
Recognising the signs of hypothermia and frostbite
Besides dressing appropriately to exercise in the cold, it is also helpful to know the signs of hypothermia and frostbite. Symptoms of hypothermia and frostbite can vary, but early symptoms of hypothermia include feeling cold, shivering, and signs of apathy or withdrawal. Frostbite is most likely to occur in exposed skin, such as the nose, ears, cheeks, and wrists. The first sign is usually numbness.
Two final tips:
- Take extra caution if you suffer from asthma, heart disease and any condition that is exacerbated by cold temperatures. People who suffer from conditions such as asthma and heart disease are at increased risk of injury when exercising in cold weather.
- Finally, acclimating to the cold can help when exercising in low temperatures. Short, intense exposure to cold weather with appropriate clothing and for less than one hour a few times a week can help your body get used to exercising outdoor on those cold winter days.
I hope you have found this blog useful, Sandra
Fudge, J. Exercise in the Cold: Preventing and Managing Hypothermia and Frostbite Injury. Sports Health. 2016 Mar; 8(2): 133–139.