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Arthur D. Stewart and James Hannan

Athletes have traditionally been evaluated for body composition by percent fat, percent muscle, and somatotype. Since the late 1980s, dual X-ray absorptiometry (DXA) has offered total and regional body composition of bone mineral content (BMC), lean tissue and fat, but studies involving athletes are rare (11) and have not included regional tissue distribution. In the present study, DXA was used to compare a total of 121 male subjects belonging to 9 different athletic groups and controls. ANOVA showed total tissue percent BMC, lean tissue, and fat were significantly different between the various athletic groups (p < .001). Regional differences in tissue distribution between different athletic groups affect BMC and lean tissue (p < .001), but not fat (p > .05). However, athletes of the leanest groups had different fat distribution to that of nonexercising controls (p < .01). It appears that fat distribution is nonspecific in its response to exercise, while lean and BMC distributions show highly specific adaptations to specific sports.

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Adam J. Zemski, Elizabeth M. Broad, and Gary J. Slater

body composition are surface anthropometry and dual-energy X-ray absorptiometry (DXA) ( Ackland et al., 2012 ; Zemski et al., 2015 ). Surface anthropometry, which includes the indirect assessment of subcutaneous fat, is an easily accessible, inexpensive, mobile, and robust method of assessment. The

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Erik Sesbreno, Gary Slater, Margo Mountjoy, and Stuart D.R. Galloway

performance in the field. Dual-energy X-ray absorptiometry (DXA) is increasingly integrated into the monitoring of athletic populations to provide timely information on both absolute and relative whole-body and regional body composition, plus bone health ( Meyer et al., 2013 ). However, without careful

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Nathan F. Meier, Yang Bai, Chong Wang, and Duck-chul Lee

Body composition is a significant health indicator. A wide range of devices and methods are available for its measurement, such as underwater weighing, skinfold testing, body mass index, dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance analysis (BIA). Changes in body composition

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Flinn Shiel, Carl Persson, Vini Simas, James Furness, Mike Climstein, Rod Pope, and Ben Schram

Dual energy X-ray absorptiometry (DXA) uses a machine originally developed to provide information about bone mineral density, with the additional capability to assess and analyze body composition (BC) while imparting only low levels of radiation (less than a thousandth of the maximum recommended

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Adam J. Zemski, Shelley E. Keating, Elizabeth M. Broad, and Gary J. Slater

measures are unable to accurately quantify absolute ( Doran et al., 2014 ; Reilly et al., 2009 ; Zemski et al., 2018 ), or changes in, FFM and FM ( Silva et al., 2009 ). Given this limitation, anthropometric data are increasingly being complemented by other measures. Dual-energy X-ray absorptiometry (DXA

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Grant M. Tinsley and Brett S. Nickerson

of common methods, including dual-energy X-ray absorptiometry (DXA). However, the requirement of an overnight fasting period imposes limitations for when and how many assessments can be conducted. Nonetheless, the importance of an overnight fast prior to DXA assessment has been confirmed by reports

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Jason Wicke and Genevieve A. Dumas

Body segment inertial parameters are required as input parameters when the kinetics of human motion is to be analyzed. However, owing to interindividual differences in body composition, noninvasive inertial estimates are problematic. Dual-energy x-ray absorptiometry (DXA) is a relatively new imaging approach that can provide cost- and time-effective means for estimating these parameters with minimal exposure to radiation. With the introduction of a new generation of DXA machines, utilizing a fan-beam configuration, this study examined their accuracy as well as a new interpolative data-reduction process for estimating inertial parameters. Specifically, the inertial estimates of two objects (an ultra-high molecular density plastic rod and an animal specimen) and 50 participants were obtained. Results showed that the fan-beam DXA, along with the new interpolative data-reduction process, provided highly accurate estimates (0.10–0.39%). A greater variance was observed in the center of mass location and moment of inertia estimates, likely as a result of the course end-point location (1.31 cm). However, using a midpoint interpolation of the end-point locations, errors in the estimates were greatly reduced for the center of mass location (0.64–0.92%) and moments of inertia (–0.23 to –0.48%).

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Nidia Rodriguez-Sanchez and Stuart D.R. Galloway

Dual energy x-ray absorptiometry (DXA) is a popular tool to determine body composition (BC) in athletes, and is used for analysis of fat-free soft tissue mass (FFST) or fat mass (FM) gain/loss in response to exercise or nutritional interventions. The aim of the current study was to assess the effect of exercise-heat stress induced hypohydration (HYP, >2% of body mass (BM) loss) vs. maintenance of euhydration (EUH) on DXA estimates of BC, sum of skinfolds (SF), and impedance (IMP) measurements in athletes. Competitive athletes (23 males and 15 females) recorded morning nude BM for 7 days before the first main trial. Measurements on the first trial day were conducted in a EUH condition, and again after exercise-heat stress induced HYP. On the second trial day, fluid and electrolyte losses were replaced during exercise using a sports drink. A reduction in total BM (1.6 ± 0.4 kg; 2.3 ± 0.4% HYP) and total FFST (1.3 ± 0.4 kg), mainly from trunk (1.1 ± 0.5 kg), was observed using DXA when participants were HYP, reflecting the sweat loss. Estimated fat percent increased (0.3 ± 0.3%), however, total FM did not change (0.1 ± 0.2 kg). SF and IMP declined with HYP (losses of 1.5 ± 2.9% and 1.6 ± 3% respectively) suggesting FM loss. When EUH was maintained there were no significant changes in BM, DXA estimates, or SF values pre to post exercise, but IMP still declined. We conclude that use of DXA for FFST assessment in athletes must ensure a EUH state, particularly when considering changes associated with nutritional or exercise interventions.

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Marta C. Erlandson, Shonah B. Runalls, Stefan A. Jackowski, Robert A. Faulkner, and Adam D.G. Baxter-Jones

training per week and level of competition) and age at retirement as well as the reason for retirement from gymnastics activity. Dual-Energy X-Ray Absorptiometry and HSA Body composition measurements were performed in 1995 using a Hologic QDR 2000 dual-energy X-ray absorptiometry (DXA) scanner (Hologic Inc