Methodology Review: Using Dual-Energy X-Ray Absorptiometry (DXA) for the Assessment of Body Composition in Athletes and Active People

Abstract

Dual energy X-ray absorptiometry (DXA) is rapidly becoming more accessible and popular as a technique to monitor body composition, especially in athletic populations. Although studies in sedentary populations have investigated the validity of DXA assessment of body composition, few studies have examined the issues of reliability in athletic populations and most studies which involve DXA measurements of body composition provide little information on their scanning protocols. This review presents a summary of the sources of error and variability in the measurement of body composition by DXA, and develops a theoretical model of best practice to standardize the conduct and analysis of a DXA scan. Components of this protocol include standardization of subject presentation (subjects rested, overnight-fasted and in minimal clothing) and positioning on the scanning bed (centrally aligned in a standard position using custom-made positioning aids) as well as manipulation of the automatic segmentation of regional areas of the scan results. Body composition assessment implemented with such protocol ensures a high level of precision, while still being practical in an athletic setting. This ensures that any small changes in body composition are confidently detected and correctly interpreted. The reporting requirements for studies involving DXA scans of body composition include details of the DXA machine and software, subject presentation and positioning protocols, and analysis protocols.

Seasonal Changes in Whole Body and Regional Body Composition Profiles of Elite Collegiate Ice-Hockey Players

“…A second objective of the study was to evaluate the regional changes in body composition. The use of DXA allows for precise and accurate whole-body and regional (i.e., arms, legs, android, gynoid) body composition measures (1,4,22), which we believed would be reflective of various sport specific demands, and provide further insight into the current composition profiles of elite hockey players across multiple time points.…”

Disparate Body Composition Outcomes for Underwater Weighing, Dual-Energy X-Ray Absorptiometry, and Two Bioelectrical Impedance Devices in Overweight Young Adults

“…Other experts, however, have taken issue with the manifest limitations of DXA, including minor systematic errors associated with altered hydration status [18,19] methodological difficulty in parsing overlapping regions of bone and soft tissue [20], a tendency to significantly under-predict % BF in lean subjects [21,22], and signal attenuation with sagittal abdominal diameter > 20 cm leading to diminished accuracy in obese populations [23][24][25]. These issues are in addition to broad inability to directly compare DXA outcomes from disparate DXA instruments, even those from the same manufacturer, due to proprietary predictive algorithms and other non-trivial performance disparities [26,27]. Moreover, DXA presents many disadvantages more traditionally associated with complex laboratory measures, such as prohibitive cost, immobility, limited availability, and the need for certified operators [26].…”

“…These issues are in addition to broad inability to directly compare DXA outcomes from disparate DXA instruments, even those from the same manufacturer, due to proprietary predictive algorithms and other non-trivial performance disparities [26,27]. Moreover, DXA presents many disadvantages more traditionally associated with complex laboratory measures, such as prohibitive cost, immobility, limited availability, and the need for certified operators [26].…”

Rheumatoid Cachexia, a Metabolic Rheumatoid Arthritis Disorder: Pathophysiological Mechanisms, Diagnostic Tools and Current Therapeutic Strategy

“…Dense pixels corresponding to the bone are separated from less dense soft-tissue pixels [ Figure 3]. The soft-tissue compartment is then analysed to separate fat mass from lean body mass (LBM) [31]. DXA has emerged as the most clinically useful technique for measuring bone and soft-tissue mass [32].…”