Define Nutritional Requirements in Cold and Polar Environment?
Energy requirements are the major consideration for providing nutritional support in a cold environment. Energy expenditure is usually limited by the rate of heat build up and hypoxia, respectively in hot and altitude environments whereas in cold, no such type of restriction exists. Energy requirements in cold environment are influenced by the intensity of the cold, wind speed, physical factors (like melting snow, locomotion on icy or snow covered surfaces etc.) and altered solar periodicity in Arctic and Antarctic areas.
Cold exposure increases energy requirements. It is reported that people in cold climate normally eat more than those in warm climate. The increased energy requirements are due to the 'hobbling' effect of the clothing weight (7-10 kg) and are associated with the efforts of locomotion. The weight of cold weather clothing has decreased as technology has improved; however, clothing is still a considerable burden. It appears that the heat loss in a cold environment is considerably reduced through thermoregulation, clothing and behaviour i.e. seeking shelter whenever possible, creating or moving to warmer environments. Moreover, skeletal muscle contractions, either during voluntary exercise or involuntary shivering are the major source of metabolic heat produced to protect against cold stress. These are a few mechanism adapted by our body to regulate, the body temperature in conditions of cold. Let us next get to know about the concept of thermoregulation.