Physiological Adaptations and Nutritional Concerns for Training and Exercising in the Cold
Exposure to extreme cold weather can produce significant physiological and psychological challenges. Cold is the primary environmental stressor concerning the implicit nature of various outdoor winter sports. This article briefly discusses the physiological challenges and provides practical exercise and nutritional guidelines for training in extreme cold environments (< 32ºF). Guidelines will be recommended to prevent such problems as dehydration, hypothermia, and insufficient calorie intake. These recommendations should be quite applicable in terms of training for alpine ski or cross-country events.
Physiological Responses and Training in the Cold
Cold acclimatization is not a well-understood process. An individual’s tolerance to cold is significantly influenced by one’s body fat content (McArdle et al., 2001). Humans have much less capacity for adaptation to long-term cold exposure than to heat exposure. In general, an athletes’ responses to cold could deal with three aspects: increasing heat production, reducing heat loss and mobilizing metabolic fuels (Smolander et al., 1992; & Falk, 1994). The optimal-preparation for cold acclimatization required training at moderate exercise-intensity and longer duration. Warming up with a short duration and high-intensity protocol would have been ineffective (Castellani et al., 1999; & Armstrong, 2000).
Brouns (1992) indicated that maintaining adequate energy storage and fluid balance should be the primary nutritional goals during athletic competition in the cold. Although athletes may not sweat a lot under the cold environment, they still needed to consume proper amount of fluid prior and during the competition. A considerable amount of fluid may be lost when athletes are warming and humidifying their respiratory passages. However, the excessive intake of water could also pose a problem, because the peripheral vasoconstriction could further cause cold-induced dieresis (Murray, 1995; & Eberle, 2000). Ideally, the fluid intake should not exceed 600-800ml per hour in competition.
The simple motion such as walking on snow would need double the amount of energy compared when walking at sea level at the same speed (Eberle, 2000). A daily 4,500 Calories intake was ideal with 70-80 per cent of calorie-resources to come from carbohydrate-rich foods. In the cold environment, the increase in carbohydrate metabolism is substantially larger than that of fat (Brouns, 1992; & Eberle, 2000). Therefore, it was preferable for athletes to replenish more carbohydrate, rather than fat, in the cold environment. Some researchers suggest that carbohydrate feeding with water (30-100g/L) will result in additive benefits to exercise performance (Murray, 1995; & Brouns, 1992).
The physiological and psychological challenges in training and exercising in the cold are factors that winter athletes contend with on a daily basis. Athletes should be aware of the early warning signs of cold injury, such as numbness in the fingers and toes or a burning sensation in the nose and ears (McArdle et al., 2001). Body-heat caused by shivering and physical movement are immediate responses to compensate for lower body-temperatures due to a cold environments. Improving physical fitness and taking preventative steps in training and nutrition will enhance one’s thermo-regulatory defense against cold stress. It is suggested that great attention should be put upon the duration and intensity training, proper hydration, and adequate calories coming from a predominant carbohydrate diet.
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