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Cold Weather Training
Outdoor athletes training during winter know that training conditions may not always be optimal
Outdoor athletes training during winter know that training conditions may not always be optimal. Furthermore those who compete in winter sports are fully aware of the problems that can occur when training in inclement weather. Training in cold environments presents a serious challenge to the outdoor athlete, and if rain or water immersion is added to the competition or training demands it increases the demands placed upon the athlete. Therefore it is essential to prepare adequately for training and competition in cold climates. To do this we must understand how the body will respond to cold exposure. The response of the body to cold exposure will be a function of the effect of exercise on heat production and the effect of clothing on the retention of body heat. It is the interaction of these factors which will inform the best strategy for training and competition.
A number of physiological responses occur during cold exposure. When core temperature drops to 35°C (from approximately 37°C under normal conditions), constriction of the peripheral blood vessels occurs. This process draws blood away from the body’s surface, attenuating the effect of the cold and reducing heat loss to the external environment, i.e. outside of the body.
To further counteract the loss of heat the body also initiates repeated, rapid, rhythmical contractions, commonly known as shivering. This is done to generate metabolic heat production. Additionally, fidgeting and increased physical activity may also occur and can help to off-set heat loss.
The extent of heat loss and subsequent necessity for heat retention or generation will also be affected by body composition. Subcutaneous body fat has a high thermal resistance, meaning that athletes with a high body fat percentage maintain higher core temperature than leaner counterparts. However, this may have significance for only a minority of athletes as the necessary body fat percentage to gain this insulative effect may be in excess of 25% body fat. This percentage is considerably higher than the reported ideal body composition for all but a few specialised sports.
Physiological responses to cold exposure are altered with repeated exposure to cold as a function of acclimatisation, habituation and insulative acclimatisation. These adaptations to cold exposure will depend on the duration and intensity of cold exposure.
Habituation can occur during acute exposure to cold environment 3-5 times per week. Frequent exposure to the cold results in a blunted response to the cold including a reduction in the constriction of blood vessels and reduced shivering, the time of exposure should be < 1hr per exposure during this period.
Insulative acclimatisation occurs as an adaptation to chronic cold exposure, resulting in an increased rate of skin temperature decline and reduced skin heat loss by conduction. This acts to reduce the amount of heat lost at the onset of initial cold exposure.
Counter the cold
The primary role of clothing is to maintain a stable core temperature of the body, ideally 37°C. All clothing choices should be made with this in mind. Heavy cottons, while plentiful, are not the ideal choice as their tendency to absorb and hold moisture on the skin reduces their insulative effect and may increase heat loss.
The ideal cold weather clothing combination should consist of a layers approach. This allows for sufficient containment of heat when the exercise begins. The use of layers also allows for the removal of clothing as exercise intensity increases (increasing internal heat production) or as environmental conditions improve(increased external temperature).
This layered approach should consist of:
- A base layer (polyester/polypropylene) in direct skin contact, which has the ability to wick moisture away from the skin to the outer layers.
- The mid layer should provide insulation (polyester/wool blend). This should form the bulk of the clothing and may be multiple layers depending on climactic conditions.
- When needed, the first two layers should be covered by an outer layer, which will allow moisture to escape while also repelling wind and rain.
- All cold weather training should, where possible, contain gloves and a hat/ear cover. Peripheral constriction of blood vessels draws blood from the fingers. Gloves become an essential component in cold weather sports which require finger dexterity, i.e. biathlon or ball sports that require catching or throwing.
Moderate physical activity is an effective method of counteracting the effects of cold exposure. When exercising in cold environments it is essential that continuous physical activity is maintained so that the level of metabolic heat production during exercise is not reduced. While the initiation of exercise will reverse the peripheral constriction of blood vessels allowing blood flow to return to the outer shell of the body, the increased heat lost to the environment should be offset by the heat production from exercise. Intermittent or stop-go exercises are not recommended in cold conditions as the periods of low activity will release heat while producing heat at a reduced rate, reversing the positive heat generating effects of exercise. Similarly, low intensity exercise is not recommended as the heat produced by completing the activity is not of a sufficient level to offset the heat lost by increased peripheral blood flow.
Sports that require water immersion or greater exposure to wet weather present a greater challenge to winter sport athletes. The addition of rain or total body water immersion will result in increased heat loss that can be begin with only a minimal reduction in environmental temperature. It is essential that athletes exercising in cold climates in conjunction with exposure to water be given additional thermal protection by using barrier clothing i.e. wet suit/rain clothing. The use of barrier clothing helps to decrease the temperature gradient between the body and the outside environment. It is the difference in temperature which drives heat loss, and therefore, the reduction of this difference can help to reduce heat lost to the environment.
Adaptations to cold:
- Reduced blood flow to extremities
- Increased heat production: Activity/shivering
- Clothing to maintain body temperature
- Maintains body temperature
- Numerous layers
- Base layer close to skin
- Insulative layer
- Wind/rain protection
- Gloves and hat essential
- Use barrier clothing in wet conditions
- Use exercise to generate heat
- Continuous moderate activity
- Avoid stop-start activity
- Ensure intensity is sufficient to offset heat loss