. "20 Energy and Macronutrient Requirements for work at High Altitudes." Nutritional Needs in Cold and High-Altitude Environments: Applications for Military Personnel in Field Operations. Washington, DC: The National Academies Press, 1996.
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It is increasingly evident that soldiers participating in field training exercises, particularly those in mountainous terrain, consistently have high rates of energy expenditure and limited dietary energy intakes (Hoyt et al., 1991, 1994a) (Table 20-1). Why are soldiers characteristically in negative energy balance? The following discussion will attempt to address this question and others posed by the Committee on Military Nutrition Research.
Exercise Energy Expenditure
Duration of Activity
High rates of energy expenditure can be attributed in part to the large portion of the day that soldiers spend in physical activity. For example, monitoring of ambulatory activity showed that soldiers were active around 17.3 ± 0.2 h/d (mean ± SD) (n = 20) over the course of 11 days during a physically demanding winter military training course (Hoyt et al., 1991). Similarly, Special Operations Forces soldiers were active about 16 ± 2 h/d during a 6-d military field training exercise at 2,500 to 3,100 m (8,202 to 10,171 ft) elevation on Mount Rainier (elevation = 4,392 m [14,410 ft], Mount Rainier National Park, Wash.) (Hoyt et al., 1994a).
TABLE 20-1 Ration Consumption and Estimated Energy Expenditure of Soldiers in the Field
3 to 34 days
3,490 ± 640 kcal/d
(range: 2,000 to 4,700 kcal/d)
Food energy intake
2,410 ± 400 kcal/d
(range: 1,780 to 2,880 kcal/d)
280 ± 70 g/d
(range: 190 to 385 g/d)
NOTE: These data are from 11 recent field studies of 781 soldiers. Values are means ± SD of study averages for each ration tested. Meal, Ready-to-Eat versions III (n = 61), VI (n = 342), VII (n = 129), and VIII (n = 148); Ration, Lightweight (n = 253); and Ration, Cold Weather (n = 48) were tested. About two-thirds of the available food energy was consumed.