Rintamäki H, Mäkinen T, Oksa J, Latvala J
Oulu Regional Institute of Occupational Health, Finland.
Arctic Med Res. 1995;54 Suppl 2:32-6.
Although a lot of attention is focused on problems of energy balance and nutrition in cold environment, water balance has received less attention. In a cold environment the water balance might be disturbed because the need of water could be increased, the use of water could be decreased and the redistribution of blood could change water volume in circulation. In dehydrated subjects, exercising at -15 degrees C at submaximal work level, both oxygen uptake and heart rate were significantly higher during water deprivation while the anaerobic threshold was lower. The time before reaching exhaustion was also shortened. However, maximal oxygen uptake and maximal muscle strength were not affected. The results suggest lower efficiency, higher physical strain and earlier exhaustion of dehydrated subjects in cold. After repletion of 1.8% body weight loss by an equal amount of fluid (5% sucrose solution) the oxygen uptake was significantly decreased at a submaximal work level at -20 degrees C, suggesting an improved mechanical efficiency and decreased physical strain. Although physical performance could be restored by rehydration, a rapid rehydration is not recommended because of increased diuresis, increased blood pressure and vigorous shivering stimulated by cold fluids. Instead, a continuous maintenance of water balance is recommended, with a fluid temperature above 25-30 degrees C and with a carbohydrate content below 7%.
尽管在寒冷环境中，很多注意力都集中在能量平衡和营养问题上，但水平衡却较少受到关注。在寒冷环境中，水平衡可能会受到干扰，因为水的需求可能增加，水的利用可能减少，血液的重新分配可能会改变循环中的水量。在脱水受试者中，在-15摄氏度下以次最大工作强度运动时，缺水期间的摄氧量和心率均显著升高，而无氧阈值则较低。达到疲劳的时间也缩短了。然而，最大摄氧量和最大肌肉力量并未受到影响。结果表明，脱水受试者在寒冷环境中的效率较低、身体应变较高且疲劳较早出现。通过等量液体（5%蔗糖溶液）补充1.8%体重的损失后，在-20摄氏度的次最大工作强度下，摄氧量显著降低，这表明机械效率提高且身体应变降低。尽管补水可以恢复身体机能，但由于冷液体刺激导致利尿增加、血压升高和剧烈颤抖，不建议快速补水。相反，建议持续维持水平衡，液体温度高于25-30摄氏度，碳水化合物含量低于7%。
