Nutritional Needs in Cold and High-Altitude Environments Applications for Military Personnel in Field Operations (1996) / Chapter Skim
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20 Energy and Macronutrient Requirements for work at High Altitudes
20 Energy and Macronutrient Requirements for work at High Altitudes
Pages 379-392
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From page 379... ...
Energy requirements determine the total caloric contribution required Tom food and body energy stores. The specific Mel combusted to meet energy requirements depends primarily on the intensity and duration of work performed, macronutrient availability Tom rations and body energy stores, and environmental conditions (Ahlborg and Felig, 1982; Felig and Wahren, 1975; Stein et al., 1989; Young and Young, 1988~.
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From page 380... ...
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 hi, Mount Rainier National Park, Wash.)
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From page 381... ...
(FAO/WHO/UNU, 1985~. Recent studies using the doubly labeled water method to measure total daily energy expenditure have found that the work level of soldiers commonly exceeds 2.10 x BMR.
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From page 382... ...
(1967) , mean oxygen consumption in five young males increased significantly on the first day at altitude, remained significantly elevated on day 4, and then decreased progressively towards control values by day 8.
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From page 383... ...
Additionally, in a study of 10 women, a relatively large intrasubject coefficient of variation in resting energy expenditure was attributed in part to the effect of the menstrual cycle on energy expenditure (De Boer et al., 1987~. Energy Intake Field Ration Consumption at Sea Level Soldiers normally, perhaps innately, do not consume enough food to meet the energy demands of strenuous field training exercises, regardless of the type of field ration they are consuming (Table 20-1~.
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From page 384... ...
This picture might be modified by physical exercise and During extreme or oaaly tolerated hypoxia where the general aversion to food, water, and salt intake may simply reflect altitude illness rather than an adaptive physiologic mechanism. The reduced appetite and thirst with acute exposure to moderate, well-tolerated altitudes appears to support physiologic hypohydration and adaptation to acute hypoxia (Hoyt and Honig, 1996~.
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From page 385... ...
, is enough energy to meet a 2,000 kcal energy deficit per day for over a month. In contrast to the large fat energy reserves, body carbohydrate reserves constitute only around 2 percent of the body's energy reserves and are readily depleted in the absence of adequate dietary carbohydrate intake (Sahlin, 1986~.
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From page 386... ...
Thus, the rate of force generation can be estimated as total body weight divided by the time during each stride that a single foot was in contact with the ground (Hoyt et al., 1994b; Kram and Taylor, 1990~. A second, related finding is that soldiers performing similar tasks in mountainous terrain have energy expenditures proportional to their total weight (Hoyt et al., 1994a)
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From page 387... ...
Field studies are planned to test whether macronutrient requirements of physically active soldiers can be quantified using this approach. AUTHORS' CONCLUSIONS AND RECOMMENDATIONS Soldiers participating in field training exercises, particularly those in mountainous terrain, are characteristically in negative energy balance.
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From page 388... ...
Waters 1989 Use of doubly labeled water technique in soldiers training for jungle warfare.
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From page 389... ...
Cymennan 1991 Doubly labeled water measurement of human energy expenditure during strenuous exercise.
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From page 390... ...
Askew 1990 Voluntary consumption of a liquid carbohydrate supplement by Special Operations Forces during a high altitude cold weather field training exercise. Technical Report T20-90.
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From page 391... ...
Van Es, and F ten Hoor 1986 Use of the doubly labeled water technique in humans during sustained heavy exercise.
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