The CMNR has separated their recommendations for future research into these three components below. However, an issue that the Committee on Military Nutrition Research considers of overriding importance is the appropriate analyses of all variables from both studies with attention to longitudinal analyses of data on individuals. The committee believes that the presentation of the unique data from these studies solely as group means may mask many interesting and physiologically important scientific results. The CMNR realizes that these types of data analyses may require additional state-of-the-art biostatistical techniques and it encourages the Military Nutrition Division to consult with individuals, when necessary, to obtain the additional expertise to perform the appropriate analyses.
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Ranger studies offer the opportunity to collect invaluable information that is of health benefit not only to the Army but also to the civilian population as a whole. The committee strongly encourages continued research with the Ranger Training Classes particularly under varying environmental conditions. This research should address issues that become more apparent with completion of the analysis of the Ranger II study as integrated with the findings from Ranger I.
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The investigators should refine the data analyses. The data are unique and consideration of data on an individual subject basis should be emphasized.
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Data from both studies, to the extent possible, should be evaluated on the basis of individual medical and psychological profiles collected prior to the study, followed longitudinally across the phases of Ranger training, and at specific points in time post-training (eg., 30 days, 6 months, 1, and 5 years).
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Biostatisticians should be identified who can assist with the evaluation of the data from both Ranger I and II studies using state-of-the-art techniques to optimize the use of this significant database.
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Adequacy of protein intake, particularly during field training exercises, should be investigated by comparing estimated food intake levels during field exercises with food intake during periods of greater ration consumption. Was protein intake indeed adequate to maintain functional protein mass? Because
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of the apparent changes in hydration of fat-free mass further analyses of data should be conducted to determine changes in protein mass.
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Using the data on the total number of subjects that have been studied to date in the Ranger Training projects, it would be important to determine possible correlations between initial body composition and the outcome physiological variables measured in the studies. The use of multicompartment models that would measure fat mass, skeletal mass, total body water, and protein mass would be desirable. Associations among variables and especially with fat-free mass may also be helpful. These data may also be useful for generating predictors of successful training completion.
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Post-training, there was evidence that the ten individuals studies gained considerable body weight. The mean body weight 5 weeks post-training was above the pre-training mean weight, with a larger increase in relative amounts of fat to lean. The composition of the weight regained and the length of time to restore lean body mass are important considerations and should be evaluated as this has implications for post-training behavior (i.e., food intake, exercise), susceptibility to infections, and possibly other health implications.
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World War II studies showed that muscle recovery from severe wounds was slow. Is significant loss of lean body mass in the short period of time of the Ranger studies also slow to recover following refeeding? Reports of individuals following refeeding having problems with diarrhea also raise the question of cell membrane permeability and possibly abnormal fat absorption.
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Using the data from the two Ranger studies the scientific team is encouraged, to the extent possible, to develop a mathematical model of predictors for success, and risk factors for failure, that can be provided to the Ranger Training Brigade and evaluated through future selective research.
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Because group average plasma zinc values were elevated, and because dietary intakes of excess zinc can lead to immunosuppression, available data should be evaluated further in an effort to determine the cause of the hyperzincemia. Comments in the discussion of question 3 in Part II provide specific suggestions.
