The Relationship of Soldier Body Composition to Physical Performance
The military has a major interest in the relationship of body composition to the performance of physical tasks. The relationship is important in decisions to accept or reject recruits for military service and has implications for the individual in regards to retention and advancement within the services. Issues of body composition have financial implications as well for the military, due to the high cost of training replacements when individuals are discharged for failure to meet the established standards. But the discharge of such trained and experienced specialists can affect unit readiness and performance.
The Army contends that all military personnel need to maintain a certain level of physical fitness to preserve combat readiness. Therefore, all are evaluated regularly for height, weight, and/or body circumference; all are also required to perform a test of aerobic fitness. The military services differ in their acceptable standards for weight and physical fitness, but obese personnel in any service who do not lose sufficient weight or body fat to meet these standards will be discharged. However, with the increasing diversity of military personnel in terms of gender, ethnicity, and age, the military questioned whether current height-weight standards were appropriate and applied uniformly in recruitment and retention.
Recognizing the importance of body composition in relation to performance of physical tasks, personnel from the U.S. Army Research Institute for Environmental Medicine (USARIEM) raised this issue with the CMNR in
1989. A task force comprised of USARIEM and CMNR members met in the fall of 1989 to plan a workshop on this topic, and the workshop outline and participants were reviewed by the CMNR at its December 1989 meeting. The invitational workshop was held at the National Academy of Sciences in Washington, D.C., on February 6–7, 1990. Speakers were asked to provide indepth reviews in their area of expertise as it applied to one or more of the following seven questions:
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Can or should physical performance assessments be used as criteria for establishing body composition standards in the services?
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What is the relationship between body composition and performance?
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Should the services establish a minimum fat-free or lean body mass standard to complement their maximal body fat standard?
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What factors should be considered in setting body composition standards?
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Are performance and body composition standards redundant?
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If performance criteria exist, are weight-fat standards needed?
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How does one rationalize the different uses of body composition for performance, appearance, and health?
The Committee's report, Body Composition and Physical Performance, (Marriott and Grumstrupp-Scott, 1992) provides responses to the seven principal questions the CMNR was asked to address and includes recommendations for future research. The report also includes the 12 invited papers presented at the workshop.
CONCLUSIONS AND RECOMMENDATIONS
On the basis of the workshop presentations and subsequent discussion by the Committee in executive session, the Committee concluded that the relationship between body composition and physical performance is associated with lean body mass rather than body fat content. No consistent relationship is shown between body fat content and physical performance (at least within the range of body composition exhibited by current military personnel), but there is a direct relationship between such performance (as measured by tests of abilities to lift and carry loads) and the amount of lean body mass. However, body weight standards are desirable insofar as body weight and composition have implications for health that go beyond physical performance. The Committee recommended that the military seriously consider establishing a minimum standard for lean body mass.
The Committee also recommended that consideration be given to developing job-related performance tests, such as lifting and carrying tasks, that are closely related to actual military activities. Such tests would be helpful in developing body composition standards that are more closely related to physical performance of military tasks. Putting such standards into place would make a body composition standard unnecessary in relation to physical performance.
Military personnel are expected to “present a trim military appearance at all times.” The Committee could not identify a relationship between a trim appearance and military performance and recommended that if the military maintains such a standard, it should develop objective criteria, to the extent possible, for evaluation of soldier appearance.
The Committee found that the current body fat standards in the military appear to discriminate against women, for the standards allow less excess over ideal weight for women compared to men. Female soldiers are required to have a greater percentage of lean body mass in relation to a gender-specific mean than are male soldiers. The Committee recommended that the accession and retention standards for body weight and fatness in men and women be reevaluated in light of this finding. These standards have since undergone modification (see Marriott and Grumstrup-Scott, 1992, p. 27). It also called for validation of the current body composition standards for the major ethnic groups represented in the military services.
The Committee also recommended that several military centers be identified to which military personnel who face separation from the services for failing to meet body composition standards could be referred. Such centers could perform measures of body composition (e.g., through dual photon densitometry and underwater weighing) that are more accurate than the usual measures based on the use of anthropometric data and formulas developed for populations that may produce significant errors in predicting the body fat for an individual.
AREAS FOR FUTURE RESEARCH
Given the military's pool of volunteer personnel, the Committee recommended research be conducted to develop service-specific standard tests of performance that reflect military activities; identify the relationship of body composition to military and physical Performance among men and women; study the relationship, by race and gender, of body composition and fat distribution for long-term health in career military personnel; and identify the relationship of injuries to bone density and lean body mass. In addition, the Committee recommended that the military conduct a retrospective study of its
Medical Remedial Enlistment Program data base to evaluate the health status and performance of its overweight recruits and other personnel. In addition, the CMNR also recommended research into the relationship of body composition to emotional and psychological health in military units; for example, the effects on the morale of a unit containing both overweight and underweight individuals.
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The full conclusions and recommendations from this report are included in Appendix E.