Cold Weather Training
With the Winter upon us, many of us will flock back to the warm comfort of indoor training at the gym. All those fun runs in the sun and tanning days are coming to a close. However, there are many of you out there that will continue to run outside, pick up some ice skates, hit the moguls, and do the polar bear swim in the local lake. Elite athletes who perform winter sports don’t let a little cold get in the way. Sometimes it takes coaches, parents, and event organizers to protect athletes from serious cold injuries as an athlete’s desire to succeed is hard to brake.
Unfortunately, multiple studies suggest that high levels of physical training or fitness do not confer thermoregulatory advantages to cold exposure. Additionally, unlike warm weather training, there are very little physiologic adjustments made by the human body to acclimatize to cold weather despite persistent exposure.
Cold weather does create a significant risk of injury; nonetheless people generally tolerate cold exposure without significant adverse effects. We generally rely on modern cold weather clothing which keeps your radiant body heat in and the cold out. Our bodies are much more efficient at dissipating heat than keeping heat in so modern technology is essential.
Cold injuries occur when the body can’t generate enough heat to keep up with losses to the environment. Body temperatures can decline affecting the extremities and core temperature. The worst injuries to the extremities can be related to trauma or frost bite.
Sports like skiing and snowboarding can generate great speeds and present many obstacles seemingly intended to break your wrist or leg. A bad bounce off a mogul on the slopes can do a number on your knee including meniscal tears, fractures, and ACL injuries.
However, the most common cold weather injury is frostbite. Frostbite occurs when exposed skin (nose, ears, cheeks) or poorly protected skin (i.e. thin gloves) temperature drops below 0 degrees Celsius. The appendages often go numb and significant pain and tissue death can occur long after re-warming.
If enough body heat is lost core body temperature can drop resulting in hypothermia. A body temperature of less than 35 degrees is the clinical definition of hypothermia and presents with significant shivering and a desire to seek shelter. Athletes often become withdrawn and apathetic desiring only to warm up. If body temperatures continue to fall sleepiness, confusion, and difficulty talking may occur. Worst case scenario, irregular heart rhythms can occur requiring emergency medical care.
Proper clothing is essential to surviving cold weather training. The goal is to avoid heat loss that causes constriction of blood vessels and shivering which can significantly affect athletic performance. The constriction of blood vessels results in a loss of nutrient supply to muscles and shivering increases energy output and oxygen consumption leading to more rapid fatigue. Hats, gloves, thicker socks, Gortex shoes, and insulated jackets and pants are required.
Increasing winds and decreasing temperature are a bad combination and require more insulation. Conversely, high intensity sporting activities that significantly increase core body temperature may require less protective clothing to avoid hypothermia. One of the biggest mistakes is continuing to wear clothes that get wet in the cold. This causes an increase in evaporative heat loss and a more rapid decline in body temperature. In fact, the convective heat loss in cold water is so rapid it can catch a polar bear club swimmers off guard and be deadly.
Another tip which can avoid problems with cold weather training is to avoid overtraining. Overtraining can result in loss of muscle and fat with an inability to consume enough calories to keep up with exertion. When energy requirements are harder to meet because of cold weather responses like shivering, it is important to add sports supplements with added protein and carbohydrates to your diet.
When glycogen stores are low, the shivering response may also be impaired and lead to dangerous amounts of heat loss. Consuming carbohydrate during endurance training is essential to avoid hypoglycemia. Sleep is also affected by overtraining which effects recovery and causes detrimental effects to your body’s ability to maintain thermal regulation. With the long winter nights and changes in the circadian rhythm sometimes sleep aids such as melatonin provide some benefit to recovery from exercise. Just as important as in warm weather training hydration is very important and requires some discipline to drink in the winter air. Use a thermal bottle to avoid having a bottle of ice!
Before training in cold weather find out what the wind chill temperature index is going to be for that day. Wind chill temperature index takes into consideration that convective heat loss increases with increased wind speeds. Wind chill temperatures of -28 to -35deg C can cause frostbite with only 10-30 minutes of exposure. Temperatures of -36 to 45deg C can cause frostbite in only 5-10 minutes of exposure. Extreme temperatures less than -45deg C can cause frostbite in 2 minutes or less!
Cold weather sports can be a lot of fun. Make sure you progress your activities slowly and avoid excessive risks that can lead to musculoskeletal injuries and thus a visit to your local orthopaedic surgeon. Additionally I will summarize the important things to remember about cold weather training:
1) Wear protective clothing that is appropriate for your level of activity and the ambient conditions
2) Change wet clothing ASAP
3) Avoid overtraining and under-nourishment with proper diet and nutritional supplementation
4) Avoid dehydration
5) Be aware of the Wind Chill Temperature Index and avoid extreme conditions