Committee on Military Nutrition Research Activity Report 1994-1999 (1999) / Chapter Skim
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F: Conclusions and Recommendations from the Workshop Report: Nutrional Needs in Cold and in High-Altitude Environments
F: Conclusions and Recommendations from the Workshop Report: Nutrional Needs in Cold and in High-Altitude Environments
Pages 141-162
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From page 141... ...
Appendix F Conclusions anti Recommenciations from the Workshop Report Nutritional Needs in Cold and in High-Altif~a7e Environments Submitted March 1996
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From page 143... ...
Because moderately cold environments lower muscle temperature, endurance of moderate physical activity actually can be theoretically increased if body core temperature can be maintained. There are conflicting data on the effects of cold exposure on muscle strength, and more research is needed to determine this relationship.
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From page 144... ...
Provision of adequate dietary energy under circumstances of either cold or high-altitude exposure will maximize the possibility of maintenance of muscle mass, and thus muscle strength. Conversely, inadequate energy intake will result in loss of muscle tissue with a concomitant decrease in strength and endurance.
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From page 145... ...
Cold-weather operations probably require a total energy intake ranging from 45 to 62 kcal/l~g body weight/d, but earlier military studies in the Arctic suggested that 4,000 kcal/d or less were actually being consumed (LeBlanc, 1957~. Current projections for energy needs in arctic conditions focus on 58 kcal/kg body weight/d (see Chapter 1 in this volume)
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From page 146... ...
If extra dietary fat is consumed primarily to meet high daily energy requirements and to prevent weight loss during military operations in cold climates, it will not necessarily have important long-term consequences. Current national dietary recommendations have been in effect for only a few years, and there is no available research evidence to suggest that a temporary deviation from a low fat diet, eaten in order to meet unusually high energy demands, would have a long-term effect on slowly developing cardiovascular pathology.
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From page 147... ...
Free radical formation, the consequence of oxidative stress, might be expected to increase in cold or in high altitude environments, due to (1) the elevation in metabolic rate that results from an increased energy expenditure; (2)
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From page 148... ...
In addition to prior nutritional status, the body composition, recent losses of body weight or lean body mass, and recent health and training history of individual soldiers should be considered prior to their participation in missions or training in cold and in high-altitude environments. In particular, the extreme losses of lean body mass described for some individuals who participated in U.S.
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From page 149... ...
Thermoregulation is also affected by a decrease in body water due to the decrease in body heat transfer to the periphery with the decrease in blood volume because it is the blood that carries the body heat to the periphery, where it is given up to the environment through evaporative heat loss. Body fluid losses of greater than 10 percent of total body water are life threatening.
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From page 150... ...
Generally, the BMR increases by 20 to 40 percent over BMR during the first days at high altitudes, and then falls somewhat over the ensuing 3 to 10 days. There may be some loss of lean body mass during this time period, occurring simultaneously with inadequate energy intake, as BMR begins to decline toward the level that existed prior to altitude exposure.
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From page 151... ...
There is good reason to conduct research on sodium requirements in cold environments especially where hard physical work is required. Excessively high sodium intake can lead to increased diuresis, which is a major concern in cold environments.
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From page 152... ...
As detailed in several chapters (for example, see Chapters 7, 10, and 11 in this volume) , physiological responses to extreme cold induce metabolic heat production, which in turn increases the need for an adequate intake of dietary energy.
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From page 153... ...
These preliminary findings are worthy of additional future studies. RECOMMENDATIONS On the basis of the papers presented by the invited speakers, discussion at the workshop, and subsequent committee deliberations, the Committee on Military Nutrition Research offers the following recommendations regarding nutrient requirements for work in cold and in high-altitude environments.
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From page 154... ...
· Water discipline is as important during military operations in intense cold and at high altitudes as it is during desert heat. Training should include water discipline measures following guidelines in military doctrines and means for their enforcement.
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From page 155... ...
· Individuals who have not yet regained lean body mass lost in prior field operations should not be deployed to cold or high-altitude environments until lean body mass is regained. · Military troops, leaders, and medical personnel being assigned to high-altitude training or missions should be fully instructed on the symptoms and signs of AMS, subacute mountain sickness, high-altitude pulmonary edema DIAPER, and high-altitude cerebral edema (HACE)
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From page 156... ...
Energy Further research is needed: · to assess the applicability to the military, both men and women, of the finding that it may be possible to maintain body weight, nitrogen balance, and muscle protein mass at optimal values during high-altitude missions. · to define energy requirements during military operations in which simultaneous exposures to intense cold and high altitudes occur, by validation of the "free-living" estimation of energy requirement based on Hoyt and Honig's proposed use of body weight, foot strike, and terrain (see Chapter 20 in this volume)
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From page 157... ...
· to resolve conflicting data on possible effects of cold exposure on muscle strength and endurance. · to examine the relationship between the aging process and acclimatization.
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From page 158... ...
High energy, palatable rations supplying at least 400 g carbohydrate per day must be provided to insure that energy intake matches energy expenditure. Restriction of fat calories to only 30 percent is not appropriate in these operational rations.
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From page 159... ...
· Individuals who have not yet regained lean body mass lost in prior field operations should not be deployed to cold or high-altitude environments until lean body mass is regained. · Energy intake of soldiers is usually inadequate when operating in the cold or at high altitudes.
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From page 160... ...
1994. Daily dietary fat and total food energy intakes Third National Health and Nutrition Examination Survey.
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From page 161... ...
1993. Cold weather field evaluation of the 18-Man Arctic Tray Pack Ration Module, the Meal, Ready-toEat, and the Long Life Ration Packet.
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