Page 39 - JSOM Summer 2022

A Comprehensive Method of Assessing

Body Composition Using Kinanthropometry in
Human Performance Training

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Laurel M. Wentz, PhD *; P. Spencer Webb, MS ; Kate Burks, MS 3

ABSTRACT
Nutrition is an essential component of Human Performance address overall physical performance, military appearance,
Optimization in Special Operations Forces (SOF) to enhance and chronic health risk but were never intended to predict mil-
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physical and mental performance, unit readiness, and mission itary-specific performance outcomes. Furthermore, body fat
success. Body composition is frequently used to monitor in- may be estimated by the Quetelet index, a ratio of body mass
dividual nutrition progress; however, using body fat percent- to height squared commonly referred to as body mass index
age is limited both by the accuracy of the assessment method (BMI), although it may not be an accurate measure of fatness
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and its association with SOF relevant performance outcomes. in athletic individuals. While BMI and waist circumference
Lower body fat and/or body mass index have generally, but may predict attrition in conventional units, SOF Operators
not universally, been correlated with higher levels of physical are focused on human performance optimization and often
performance, yet they poorly predict performance in military have more muscular physiques that are less accurately pre-
relevant tasks. As a complement to body fat, many perfor- dicted by BMI. Lower body fat and/or BMI have generally, but
mance dietitians in the SOF Human Performance Programs not universally, been correlated with higher levels of physical
utilize the International Society for Advanced Kinanthropome- performance, yet they poorly predict performance in military
4–8
try (ISAK) profile to assess body composition, proportionality, relevant tasks. Military tasks require a combination of en-
ratio of muscle to bone, and somatotype in combat Operators. durance and strength often under significant load carriage. In
Kinanthropometry is the study of human size, shape, propor- a simulated military task, Soldier performance was predicted
tion, composition, maturation, and gross function, and it is a by the ratio of total body mass to the sum of fat mass and
helpful tool for monitoring nutrition and training progress in combat load, but neither percent body fat nor BMI were sig-
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athletes and active individuals. The ISAK profile has been well nificantly correlated with military performance. A systematic
established as an international method for talent identifica- review and meta-analysis to identify predictors of military
tion, distinguishing characteristics between athletes across and performance found that the best predictors of maximal lift
within elite sports, and identifying predictors of sport perfor- capacity were biacromial breadth and chest circumference, in
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mance that can be applied in the military setting. While some addition to lean body mass and body fat. These results sug-
SOF dietitians are utilizing the ISAK profile, the challenge lies gest that physical predictors of military performance require a
in translating sport data to military relevant outcomes. We more complex anthropometric profile including muscle girths
present a series of four case studies demonstrating the util- and bone breaths, as performance is not clearly elucidated
ity of this method as a portable comprehensive assessment for from estimates of body fat. Unlike body fat, bone breadths
cross-sectional and longitudinal body composition tracking in are genetically determined and are not modified by nutrition
a military setting. and exercise, highlighting the need for a comprehensive an-
thropometric profile to recommend appropriate muscle mass
Keywords: human performance optimization; performance nu- and body fat for frame size. While BMI and waist circumfer-
trition; muscle mass; physical fitness; military ences correlate with health or fitness in population studies,
an argument could be made against using them to predict the
status of an individual because it does not account for individ-
uals with a larger bi-iliocristal (hip) bone breadth. Thus, the
Introduction purpose of this review is to highlight a more comprehensive
Nutrition is an essential component of Human Performance assessment for SOF Operator body composition for predicting
Optimization in Special Operations Forces (SOF) to enhance performance outcomes, as well as monitoring improvements
physical and mental performance, unit readiness, and mission in nutrition, exercise, and/or injury recovery. Furthermore, we
success. Body composition is frequently used to monitor in- will share case presentations showing how to apply this assess-
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dividual nutrition progress. However, using body fat percent- ment method in the SOF population.
age is limited both by the accuracy of the assessment method
and its association with SOF relevant performance outcomes. SOF Human Performance Programs offer many options for
The official body composition standards were designed to assessing body fat percentage. As a complement to body fat,
*Correspondence to wentzlm@appstate.edu
1 Dr Laurel M. Wentz is affiliated with the Department of Nutrition and Health Care Management, Appalachian State University, Boone, NC.
2 P. Spencer Webb is affiliated with the Force Resiliency Program, US Navy Explosive Ordnance Disposal Group TWO, JEB Little Creek–Ft. Story,
VA. Kate Burks is affiliated with the Human Performance Program (Contractor), 3rd Special Forces Group (Airborne), United States Army
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Special Operations Command, Fort Bragg, NC.
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