ArticleLiterature Review

The Impact of Recent Technological Advances on the Trueness and Precision of DXA to Assess Body Composition

Authors:
  • Penn State Harrisburg in Middletown PA
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Abstract

The introduction of dual-energy X-ray absorptiometry (DXA) in the 1980s for the assessment of areal bone mineral density (BMD) greatly benefited the field of bone imaging and the ability to diagnose and monitor osteoporosis. The additional capability of DXA to differentiate between bone mineral, fat tissue, and lean tissue has contributed to its emergence as a popular tool to assess body composition. Throughout the past 2 decades, technological advancements such as the transition from the original pencil-beam densitometers to the most recent narrow fan-beam densitometers have allowed for faster scan times and better resolution. The majority of reports that have compared DXA-derived body composition measurements to the gold standard method of body composition appraisal, the four-compartment model, have observed significant differences with this criterion method; however, the extent to which the technological advancements of the DXA have impacted its ability to accurately assess body composition remains unclear. Thus, this paper reviews the evidence regarding the trueness and precision of DXA body composition measurements from the pencil-beam to the narrow fan-beam densitometers.

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... A variety of body composition estimation techniques are employed in athletic populations, ranging from simple skinfold calipers to advanced medical devices such as dual-energy X-ray absorptiometry (DXA) scanners. Originally designed to estimate bone mineral density, DXA functions by quantifying the tissue attenuation of X-ray radiation, allowing for the identification of bone mass, FFM and FM (Shepherd et al., 2017;Toombs et al., 2012;Wells & Fewtrell, 2006). This technology is now widely used to assess body composition in research settings (Wells & Fewtrell, 2006) and is known to produce reliable body composition estimates, with accuracy compared with a criterion multi-compartment model potentially varying based on the population being assessed (Graybeal et al., 2020;Johnson et al., 2017;Toombs et al., 2012). ...
... Originally designed to estimate bone mineral density, DXA functions by quantifying the tissue attenuation of X-ray radiation, allowing for the identification of bone mass, FFM and FM (Shepherd et al., 2017;Toombs et al., 2012;Wells & Fewtrell, 2006). This technology is now widely used to assess body composition in research settings (Wells & Fewtrell, 2006) and is known to produce reliable body composition estimates, with accuracy compared with a criterion multi-compartment model potentially varying based on the population being assessed (Graybeal et al., 2020;Johnson et al., 2017;Toombs et al., 2012). Within the general population, it has been reported that most comparisons between DXA and criterion four-compartment models indicate a mean underestimation of body fat percentage (BF%) by DXA (Toombs et al., 2012). ...
... This technology is now widely used to assess body composition in research settings (Wells & Fewtrell, 2006) and is known to produce reliable body composition estimates, with accuracy compared with a criterion multi-compartment model potentially varying based on the population being assessed (Graybeal et al., 2020;Johnson et al., 2017;Toombs et al., 2012). Within the general population, it has been reported that most comparisons between DXA and criterion four-compartment models indicate a mean underestimation of body fat percentage (BF%) by DXA (Toombs et al., 2012). However, a recent comprehensive review indicated that DXA is a valid method in multi-ethnic, African-American/Black and Caucasian populations, with insufficient information currently available for Hispanic and Asian populations (Blue et al., 2021). ...
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The present study examined cross-sectional and longitudinal relationships between total and segmental subcutaneous tissue thicknesses from ultrasonography (US) and total and segmental fat mass (FM) estimates from dual-energy X-ray absorptiometry (DXA). Traditional US FM estimates were also examined. Twenty resistance-trained males (mean ± SD; age: 22.0 ± 2.6 years; body mass: 74.8 ± 11.5 kg; DXA fat: 17.5 ± 4.5%) completed a 6-week supervised resistance training programme while consuming a hypercaloric diet. Pre- and post-intervention body composition was assessed by DXA and B-mode US. Data were analysed using Pearson's correlation (r), Lin's correlation coefficient (CCC), paired t-tests, Wilcoxon signed-rank tests and Bland–Altman analysis, as appropriate. Cross-sectionally, correlations were observed between total DXA FM and total subcutaneous tissue thickness (r = 0.88). Longitudinally, a correlation was observed between total DXA FM changes and total subcutaneous tissue changes (r = 0.49, CCC = 0.38). Correlations of similar magnitudes were observed for the upper body and trunk estimates, but DXA FM changes were unrelated to subcutaneous tissue changes for the lower body and arms. Cross-sectionally, US 2-compartment FM and DXA FM were correlated (r = 0.91, CCC = 0.83). Longitudinally, a weaker correlation was observed (r = 0.47, CCC = 0.33). In summary, longitudinal associations between US and DXA are weaker than cross-sectional relationships; additionally, correlations between US subcutaneous tissue and whole-body DXA FM appear to be driven by the trunk region rather than appendages. Reporting raw skinfold thicknesses rather than FM estimates alone may improve the utility of techniques based on subcutaneous tissue thickness, such as US and skinfolds.
... İndirekt ölçüm yöntemleri ise hidrodansitometri, antropometrik ölçümler, BİA yöntemi, kızılötesi interaktans, DEXA ve ultrason gibi yöntemlerdir. 12 Vücut kompozisyonunun değerlendirilmesinde kullanılan yöntemler laboratuvar ve sahada kullanılabilmektedir. Laboratuvar yöntemleri arasında hidrodansitometri, DEXA, potasyum-40 (K) analizi, manyetik rezonans gö-rüntüleme (MRI), bilgisayarlı tomografi ve nötron aktivasyon analizi yer almaktadır. Saha yöntemleri ise deri kıvrım kalınlığı ölçümü (SF), antropometrik ölçümler, BİA yöntemi, hava değişim pletismografisi ve ultrasonu içerir. ...
... İki bölmeli model (hidrodensitometri) ve üç bölmeli model (DEXA) vücut kompozisyonunu belirlemede kesin ve doğru bir teknik olarak kabul edilmiş yöntemlerdir. 12 Metodolojik olarak 4-C modelinde; yağ kütlesi ve yağsız kütleyi belirlemek için hidrodensitometri veya hava değişim pletismografsi, toplam vücut suyunu belirlemek için izotop seyreltme yöntemi ve kemik mineralini ölçmek için DEXA kullanılır. Kalan bölmeyi (yani protein, kemik olmayan mineraller ve glikojen) elde etmek için toplam vücut suyu ve kemik minerali yağsız kütleden çıkarılır. ...
... Her bölmenin vücut kütlesine göre oranı ve varsayılan yoğunlukları, vücut yağ yüzdesini hesaplamak için kullanılabilir. 12,15,17 BİYOKİMYASAl ÖlçÜM YÖNTEMlERİ Vücut kompozisyonu değerlendirmesine yönelik biyokimyasal yöntemler vardır. Vücudun doğrudan kimyasal analizi ile elde edilen biyolojik sabitlere dayanır. ...
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Vücut kompozisyonu yağsız vücut kütlesi ve yağ kütlesinin birleşimi olarak ifade edilen sağlıkla ilişkili bir fiziksel uygunluk parametresidir. Vücut kompozis-yonu ölçümlerinde esas olan vücut yoğunluğunu bularak vücut yağ yüzdesini hesaplamaktır. Sporcularda hem sporcu sağlığını hem de spor performansını etkilediği için yağsız vücut kütlesi ve yağ kütlesi dağılımını doğru bir şekilde tahmin etmek önem-lidir. 1 Vücut yağlılığını etkileyen önemli faktörler yaş, cinsiyet, genetik yapı, metabo-lizma, büyüme-gelişme, beslenme durumu ve fiziksel aktivite düzeyidir. Sağlık için vücut yağının belli bir oranda olması gerekir. Çok düşük vücut yağ oranı ciddi sağlık so-runlarına neden olabilirken, yüksek vücut yağ oranı özellikle yüksek abdominal yağ-lanma hipertansiyon, tip 2 diyabet, hiperlipidemi ve koroner arter hastalığı için riskli kabul edilmektedir. 2-5 Genel olarak yüksek vücut yağ kütlesi kötü fiziksel uygunluğun, yağsız vücut kütlesi ise kas uygunluğunun bir göstergesi olarak kabul edilir. 6,7 Sporcu-larda vücut yağ kütlesinin belirlenmesi çok önemli olmasına rağmen, diğer vücut bile-29 Sporcularda Vücut Kompozisyonunun Değerlendirilmesi Evaluation of Body Composition in Athletes ÖZET Vücut kompozisyonu vücut ağırlığını oluşturan tüm dokuların göreceli oranları olarak tanımla-nabilir. Temelde yağsız vücut kütlesi ve vücut yağ kütlesinin doğru tahmin edilmesi esasına dayanır. Vücut kompozisyonu hem genel sağlık hem de sporcu sağlığı ve performansı için önemli bir paramet-redir. Vücut kompozisyonu parametrelerinden vücut yağ yüzdesinin çok düşük veya çok yüksek olması sporcu sağlığını ve performansını olumsuz etkiler. Öte yandan yağsız vücut kütlesi ise iyi bir spor per-formansı göstergesi olarak kabul görmüştür. Vücut kompozisyonunu değerlendirmek için pek çok yön-tem geliştirilmiştir. Bu yöntemler içinde su altı ağırlık ölçüm yöntemi (hidrodansitometri) ve dual-energy x-ray absorbsiometrisi (DEXA) gibi yöntemler daha nicel sonuçlar vermesine rağmen sahada kullanımı maliyetli ve zahmetlidir. Hava değişim pletismografisi, bioelektrik impedans analiz (BİA) yöntemi, deri kıvrım kalınlığı gibi yöntemler ise sahada sıklıkla kullanılan yöntemlerdir. Bu yazıda vücut kompozis-yonunun önemi, spor performansına etkisi ve değerlendirme yöntemlerinden bahsedilmektedir. Anah tar Ke li me ler: Vücut bileşimi; spor performansı; sporcular ABS TRACT Body composition could be defined in terms of the relative ratio of all the tissues forming the body weight. In principle, it is based on the accurate estimation of the fat-free body mass and body fat mass. Body composition is an important parameter for both general health as well as athletic performance. Of the body composition parameters, having too low or too high values of body fat mass percentage has an adverse effect on both the overall health and performance of an athlete. On the other hand, fat-free body mass is considered to be an indication of good athletic performance. There are several methods to perform body composition analysis. Among these methods, underwater weighing (hy-drodensitometry) and dual-energy x-ray absorptiometry (DEXA) have been efficient in giving quantitative results even though they are expensive and difficult to implement in the field. For others, air displacement plethysmography, bioelectric impedance (BIA) analysis, and skinfold measurement methods are more frequently used in the field. This paper covers the importance and evaluation methods of the body composition parameter, and how it affects athletic performance.
... Considering DXA's good precision, large availability, and low radiation dose its measurement presents several advantages over other laboratory methods (Toombs et al., 2012). In the early 1990s, the replacement of the original pencil-beam densitometers by the fan-beam devices allowed for better resolution and faster scans while maintaining the accuracy, without increasing considerably the radiation dose. ...
... In the early 1990s, the replacement of the original pencil-beam densitometers by the fan-beam devices allowed for better resolution and faster scans while maintaining the accuracy, without increasing considerably the radiation dose. Thus, the burden of use of DXA for both patient and clinicians was eased (Toombs et al., 2012). However, caution must be taken when using DXA on multiple occasions, not only due to the cumulative radiation dose, but also due to the error of measurement, which limits the ability to detect small body composition changes over time, leading to misinterpreting data (Santos et al., 2010;Toombs et al., 2012). ...
... Thus, the burden of use of DXA for both patient and clinicians was eased (Toombs et al., 2012). However, caution must be taken when using DXA on multiple occasions, not only due to the cumulative radiation dose, but also due to the error of measurement, which limits the ability to detect small body composition changes over time, leading to misinterpreting data (Santos et al., 2010;Toombs et al., 2012). ...
... The extent to which the energy is attenuated when crossing the body depends on the thickness, density and chemical composition of the different tissues [11]. Originally, DXA has mainly been used for the assessment of areal bone mineral density, but nowadays it is increasingly considered the 'gold standard' for the (segmental) body composition assessment of bone mineral content, fat tissue and lean tissue [12]. The Norland Elite DXA (Swissray Medical AG, Hochdorf, Switzerland) [13] is a more recently developed DXA device, featured by a large scan window, a high weight capacity as well as a low and adaptive radiation dose. ...
... The Norland Elite DXA (Swissray Medical AG, Hochdorf, Switzerland) [13] is a more recently developed DXA device, featured by a large scan window, a high weight capacity as well as a low and adaptive radiation dose. Although DXA has numerous advantages, including a relatively short measurement time and its applicability in humans of all ages [12], this method or technique also contains some limitations. As such, the DXA device uses minimal ionizing radiation and is not portable [14]. ...
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Bio-electrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) are methods to estimate human body composition. This study aimed to compare sex-specific outcomes for estimating segmental and whole-body composition in 83 healthy participants (21.9 ± 1.5 years, 56% men) using Inbody S10 BIA and Norland Elite DXA devices. One-way repeated measures ANOVAs showed significantly lower whole-body fat% and whole-body fat mass values alongside higher whole-body lean mass values resulting from BIA when compared to DXA (both sexes: p < 0.001). In men, whole-body bone mineral content was significantly higher using BIA against DXA (p < 0.001). Regardless of sex, no significant BIA versus DXA difference was found in arm fat mass (men: p = 0.180, women: p = 0.233), whereas significantly lower leg fat mass values were found with BIA versus DXA (both sexes: p < 0.001). Additionally, significantly higher arm lean mass (both sexes: p < 0.001) and leg lean mass (only women: p < 0.001) were found in BIA versus DXA. Moderate to very strong positive associations (p < 0.05) between BIA and DXA outcome measures were found, except for arm fat mass (men: p = 0.904, women: p = 0.130) and leg fat mass (only men: p = 0.845). This study highlights (sex-dependent) differences in corresponding test outcomes between BIA and DXA both at the segmental and whole-body level.
... Precision errors refers to the closeness of agreement between multiple and independent results of measurements under standardized conditions [1]. It is independent of trueness and the difference is due to instrumental and technical factors [2]. ...
... Due to technological advancements the last decades, Dualenergy X-ray absorptiometry (DXA) is a valid tool in measuring body compartments, and DXA's availability is increasing worldwide [1,6,17e20]. The newest instrument, GE Lunar iDXA, provides measurements of fat mass, lean mass and bone mass [1,2,4]. Recent improvements in the DXA software, enCORE™ and the application CoreScan, allows in addition determination of abdominal adipose tissue, including estimations of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) [21,22]. ...
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Background & Aims High quality and precise methods are needed when monitoring changes in body composition among colorectal cancer (CRC) patients and healthy subjects. The aim of this study was to estimate precision of the Dual-energy X-ray absorptiometry (Lunar iDXA, GE Healthcare software enCORE version 16) in measuring body composition in CRC patients and healthy subjects. Methods Precision error of iDXA in measuring body composition was investigated in the current study. Thirty CRC patients and 30 healthy subjects, including both men and women underwent two consecutive whole-body DXA scan with repositioning. Precision estimates of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in the abdominal region, and total fat mass (FM), fat-free mass (FFM), lean mass (LM), bone mineral density (BMD) and bone mineral content (BMC) were calculated. Results Precision error expressed as coefficient of variation (% CV) of VAT and SAT were estimated to be 3.56 % and 3.28 % among CRC patients, and 5.30 % and 3.46 % among healthy subjects. Estimated precision errors for body masses in the total region ranged between 0.49-1.01 % and 0.40-0.88 % in CRC patients and healthy subjects, respectively. Least significant change (LSC) in VAT mass, SAT mass, FM and LM were 140.9 g, 121.4 g, 637.0 g and 701.0 g, respectively, among CRC patients. Among healthy subjects the LSC in VAT, SAT, FM and LM were 80.93 g, 98.90 g, 484.0 g and 618.0 g, respectively. Only minor and non-significant differences between the two consecutive measurements for each body compartment were observed within both populations, and we found no systematic bias in the distribution of the differences. Conclusion The Lunar iDXA demonstrated high precision in body composition measurements among both CRC patients and healthy subjects. Hence, iDXA is a useful tool in clinical following-up and interventions targeted towards changes in body composition.
... Coefficient of variation for DXA %BF measurements has been previously reported to be <2%. 22 Fat-free mass index (FFMI) was calculated as FFM divided by height in metres squared (kg/m 2 ). ...
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Introduction/background As a proxy for adiposity, body mass index (BMI) provides a practical public health metric to counter obesity-related disease trends. On an individual basis, BMI cannot distinguish fat and lean components of body composition. Further, the relationship between BMI and body composition may be altered in response to physical training. We investigated this dynamic relationship by examining the effect of US Army basic combat training (BCT) on the association between BMI and per cent body fat (%BF). Methods BMI and %BF were measured at the beginning (week 1) and end (week 9) of BCT in female (n=504) and male (n=965) trainees. Height and weight were obtained for BMI, and body composition was obtained by dual X-ray absorptiometry. Sensitivity and specificity of BMI-based classification were determined at two BMI thresholds (25 kg/m ² and 27.5 kg/m ² ). Results A progressive age-related increase in fat-free mass index (FFMI) was observed, with an inflection point at age 21 years. In soldiers aged 21+, BMI of 25.0 kg/m ² predicted 33% and 29% BF in women and 23% and 20% BF in men and BMI of 27.5 kg/m ² predicted 35% and 31% BF in women and 26% and 22% BF in men, at the start and end of BCT, respectively. Sensitivity and specificity of BMI-based classification of %BF were poor. Soldiers below BMI of 20 kg/m ² had normal instead of markedly reduced %BF, reflecting especially low FFMI. Conclusions BCT alters the BMI–%BF relationship, with lower %BF at a given BMI by the end of BCT compared with the beginning, highlighting the unreliability of BMI to try to estimate body composition. The specific BMI threshold of 25.0 kg/m ² , defined as ‘overweight’ , is an out-of-date metric for health and performance outcomes. To the extent that %BF reflects physical readiness, these data provide evidence of a fit and capable military force at BMI greater than 25.0 kg/m ² .
... We did not assess whole-body muscle mass, and more test methods should be used to ensure the accuracy of chest wall muscle mass measurement. Dualenergy x-ray absorptiometry (DXA) is considered the gold standard technique in clinical practice to estimate fat-free body mass, 11 but it is not available in many hospitals and can be costly. Bio-electrical impedance analysis (BIA) and skinfold thickness measurement (STM) are more readily available to health care teams, but there are no good coefficients obtained in truck fat-free mass assessment with BIA and DXA. ...
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Background and objective Many bronchiectasis patients suffer dyspnea, decreased exercise tolerance, and low body mass index. Chest wall muscles play a special role in respiratory movement and make up parts of skeletal muscles. This study aimed to examine the chest wall muscle thickness and their relationship with disease severity in bronchiectasis. Methods We retrospectively included 166 patients with bronchiectasis and 62 patients with pneumonia as comparators. The thickness of chest wall muscle as determined in chest CT, pulmonary function, and Bronchiectasis Severity Index (BSI) score were recorded. We compared the thickness of the chest wall muscle in two groups and assessed the relationships among chest wall muscle thickness, pulmonary function, and BSI score. Results Chest wall muscle thickness of the anterior midclavicular line and posterior exterior scapula were thinner in bronchiectasis patients than comparators both above the aortic arch level and at the aortic arch window level. Muscle thickness of the posterior interior scapula above the aortic arch level was significantly thinner in bronchiectasis patients. Chest wall muscle thickness at the anterior midclavicular line both the above aortic arch level and at the level of the aortic arch window were related to diffuse capacity in bronchiectasis patients. Anterior chest wall muscle thickness above the aortic arch was found to be a risk factor of disease severity. Conclusion Anterior chest wall muscles in the upper and middle chest were thinner in bronchiectasis patients than in comparators, and had relationship with spirometry and diffuse compacity factors. We provide another method to conveniently assess bronchiectasis severity.
... The validity of fat mass derived by Lunar Prodigy has been evaluated against the 4-compartment model, the tool that is currently considered the gold standard method of body composition appraisal, resulting in 1.7e2.0% higher fat mass estimates with the narrow fan-beam DXA equipment [24]. ...
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Background and aim A high intake of whole grain foods is inversely associated with body mass index (BMI) and body fat in observational studies, but mixed results have been found in interventional studies. Among whole grains, rye is the richest source of dietary fiber and meals containing high-fiber rye foods have shown increased satiety up to 8 hours, compared to meals containing refined wheat products. The aim of the study was to determine the effect of consuming high fiber rye products, compared to refined wheat products, on body weight and body fat loss in the context of an energy restricted diet. Methods After a 2-week run-in period, 242 males and females with overweight or obesity (BMI 27-35 kg/m²), aged 30-70 years, were randomized (1:1) to consume high fiber rye products or refined wheat products for 12 weeks, while adhering to a hypocaloric diet. At week 0, week 6 and week 12 body weight and body composition (dual energy e-ray absorptiometry) was measured and fasting blood samples were collected. Subjective appetite was evaluated for 14 hours at week 0, 6 and 12. Results After 12 weeks the participants in the rye group had lost 1.08 kg body weight and 0.54 % body fat more than the wheat group (95% confidence interval (CI): 0.36;1.80, p<0.01 and 0.05;1.03, p=0.03, respectively). C-reactive protein was 28% lower in the rye vs wheat group after 12 weeks of intervention (CI: 7;53, p<0.01). There were no consistent group differences on subjective appetite or on other cardiometabolic risk markers. Conclusion Consumption of high fiber rye products as part of a hypocaloric diet for 12 weeks caused a greater weight loss and body fat loss, as well as reduction in C-reactive protein, compared to refined wheat. The difference in weight loss could not be linked to differences in appetite response. Clinical trial registration www.clinicaltrials.gov, Identifier: NCT03097237;
... According to the first publication showing the effectiveness of bisphosphonates in the treatment of bone loss [4], DXA contributed to the management of osteoporotic patients. The introduction of fan beam radiation source technology in 1993 allowed shortening the radiation exposure time while improving the quality of the images received [5]. Based on the BMD measurements, the T-score and Z-score parameters were defined. ...
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The application of dual-energy X-ray absorptiometry (DXA) examinations in the assessment of bone mineral density (BMD) in the lumbar spine, hip, and forearm is the basic diagnostic method for recognition of osteoporosis. The constant development of DXA technique is due to the aging of societies and the increasing importance of osteoporosis as a public health problem. In order to assess the degree of bone demineralization in patients with hyperparathyroidism, forearm DXA examination is recommended. The vertebral fracture assessment (VFA) of the thoracic and lumbar spine, performed by a highly-skilled technician, is an interesting alternative to the X-ray examination. The DXA total body examination can be useful in the evaluation of fat redistribution among patients after bariatric surgery, in patients infected with HIV and receiving antiretroviral therapy, and in patients with metabolic diseases and suspected to have sarcopenia. The assessment of visceral adipose tissue (VAT) and detection of abdominal aortic calcifications may be useful in the prediction of cardiovascular events. The positive effect of anti-resorptive therapy may affect some parameters of DXA hip structure analysis (HSA). Long-term anti-resorptive therapy, especially with the use of bisphosphonates, may result in changes in the DXA image, which may herald atypical femur fractures (AFF). Reduction of the periprosthetic BMD in the DXA measurements can be used to estimate the likelihood of loosening the prosthesis and periprosthetic fractures. The present review aims to present current applications and selected technical details of DXA. © 2021 International Scientific Information, Inc.. All rights reserved.
... 7,18 This expression of EA from Loucks 4,7,18,19 has persisted in the Triad literature despite the lack of consideration of nonpurposeful energy expenditure, which can be quite variable (and significant in many cases), concerns regarding the accuracy with which it can be determined in free living athletes, and the reliance of this measure on self-reported variables, especially dietary EI. 20 Similarly, assessments of FFM may be specific to laboratory settings but may be calculated based on the weight of the athlete in kilograms, as well as the percent body fat, which may be estimated by dual X-ray absorptiometry, air displacement plethysmography, skinfold measurements, Bod Pod, or bioelectrical impedance. 21,22 In this consensus article, we provide an operational definition of the concept of "low" EA. We shall use the terminology of low EA to refer to a level of EA that reflects energy deficiency such that there is evidence that compensatory metabolic adaptations are present that reflect the failure to consume adequate energy to support energy expenditure. ...
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The Male Athlete Triad is a syndrome of 3 interrelated conditions most common in adolescent and young adult male endurance and weight-class athletes and includes the clinically relevant outcomes of (1) energy deficiency/low energy availability (EA) with or without disordered eating/eating disorders, (2) functional hypothalamic hypogonadism, and (3) osteoporosis or low bone mineral density with or without bone stress injury (BSI). The causal role of low EA in the modulation of reproductive function and skeletal health in the male athlete reinforces the notion that skeletal health and reproductive outcomes are the primary clinical concerns. At present, the specific intermediate subclinical outcomes are less clearly defined in male athletes than those in female athletes and are represented as subtle alterations in the hypothalamic-pituitary-gonadal axis and increased risk for BSI. The degree of energy deficiency/low EA associated with such alterations remains unclear. However, available data suggest a more severe energy deficiency/low EA state is needed to affect reproductive and skeletal health in the Male Athlete Triad than in the Female Athlete Triad. Additional research is needed to further clarify and quantify this association. The Female and Male Athlete Triad Coalition Consensus Statements include evidence statements developed after a roundtable of experts held in conjunction with the American College of Sports Medicine 64th Annual Meeting in Denver, Colorado, in 2017 and are in 2 parts-Part I: Definition and Scientific Basis and Part 2: The Male Athlete Triad: Diagnosis, Treatment, and Return-to-Play. In this first article, we discuss the scientific evidence to support the Male Athlete Triad model.
... Appendicular lean mass is a surrogate for muscle mass because lean tissue in the arms and legs is striated and does not include cardiac and smooth muscle or other organs (which is included in the calculation of total lean mass) [29]. The validation and precision of DXA against whole-body computed tomography and magnetic resonance imaging has been reported [30,31]. ...
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PurposeObesity increases the risk of cancer recurrence and death in survivors of breast cancer. This study tested the hypothesis that exercise alone, diet alone, and the combination of exercise plus diet reduce body weight and improve body composition in survivors of breast cancer.Methods In this 2 × 2 factorial trial, 351 survivors of breast cancer with overweight or obesity were randomized to one of four treatment groups for 52 weeks: control, exercise alone, diet alone, or exercise plus diet. Endpoints included body weight and body composition measured by dual-energy x-ray absorptiometry.ResultsAfter 52 weeks, compared with control, diet alone [− 5.39 kg (95% CI − 7.24, − 3.55);− 6.0% (95% CI − 8.0, − 3.9)] and exercise plus diet [− 6.68 kg (95% CI − 8.46, − 4.90);− 7.4% (95% CI − 9.4, − 5.4)] reduced body weight; exercise alone did not change body weight. Compared with control, diet alone [− 3.59 kg (95% CI − 5.00, − 2.17)] and exercise plus diet [− 4.28 kg (95% CI − 5.71, − 2.84)] reduced fat mass; exercise alone did not change fat mass. Compared with control, diet alone [− 0.82 kg (95% CI − 1.50, − 0.15)] and exercise plus diet [− 1.24 kg (95% CI − 1.92, − 0.56)] reduced lean mass; exercise alone did not change lean mass. Compared with control, exercise alone, diet alone, and exercise plus diet did not change bone mineral density.Conclusion In survivors of breast cancer with overweight or obesity, diet alone or diet plus exercise produced clinically meaningful weight loss at week 52. The majority of weight loss was fat mass.
... 46,47 Fat free mass (FFM) 48 may be calculated based on the weight of the athlete in kilograms, as well as the percent body fat, which may be estimated by DXA, air displacement plethysmography, skinfold measurements, Bod Pod, or bioelectrical impedance. 49,50 Discussing patterns of food intake and behaviors with the athlete, and estimating their EA at the time that the athlete is being assessed for any one of the components of the Male Athlete Triad, can serve as an opportunity for the provider to educate and give immediate feedback to the athlete regarding suspected energy deficiency/low EA and under-fueling, as well as the possible relationship to their presenting complaint. ...
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The Male Athlete Triad is a medical syndrome most common in adolescent and young adult male athletes in sports that emphasize a lean physique, especially endurance and weight-class athletes. The 3 interrelated conditions of the Male Athlete Triad occur on spectrums of energy deficiency/low energy availability (EA), suppression of the hypothalamic-pituitary-gonadal axis, and impaired bone health, ranging from optimal health to clinically relevant outcomes of energy deficiency/low EA with or without disordered eating or eating disorder, functional hypogonadotropic hypogonadism, and osteoporosis or low bone mineral density with or without bone stress injury (BSI). Because of the importance of bone mass acquisition and health concerns in adolescence, screening is recommended during this time period in the at-risk male athlete. Diagnosis of the Male Athlete Triad is best accomplished by a multidisciplinary medical team. Clearance and return-to-play guidelines are recommended to optimize prevention and treatment. Evidence-based risk assessment protocols for the male athlete at risk for the Male Athlete Triad have been shown to be predictive for BSI and impaired bone health and should be encouraged. Improving energetic status through optimal fueling is the mainstay of treatment. A Roundtable on the Male Athlete Triad was convened by the Female and Male Athlete Triad Coalition in conjunction with the 64th Annual Meeting of the American College of Sports Medicine in Denver, Colorado, in May of 2017. In this second article, the latest clinical research to support current models of screening, diagnosis, and management for at-risk male athlete is reviewed with evidence-based recommendations.
... ere are several tools to determine body composition. Dual energy X-ray absorptiometry (DXA) determines body composition from scanning the body with X-ray beams that pass through the body and establish amount of fat mass, bone mass, and soft tissue lean mass based on composition of the tissues [2][3][4]. Visceral adipose tissue (VAT) located intra-abdominally (behind the abdominal muscles and around organs) is more metabolically active than subcutaneous adipose tissue and has been associated with insulin resistance, the metabolic syndrome (MetS), cardiovascular disease, and several types of cancer [5]. DXA provides area-specific body composition, and VAT is estimated from fat mass located in the abdominal area when subcutaneous fat has been removed [3]. ...
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Background: Reference values for visceral adipose tissue (VAT) are needed and it has been advocated that body composition measures depend on both the technique and methods applied, as well as the population of interest. We aimed to develop reference values for VAT in absolute grams (VATg), percent (VAT%), and as a kilogram-per-meters-squared index (VATindex) for women and men, and investigate potential differences between these measures and their associations with cardiometabolic risk factors (including metabolic syndrome (MetS)). Methods: In the seventh survey of the population-based Tromsø Study, 3675 participants (aged 40-84, 59% women) attended whole-body DXA scans (Lunar Prodigy GE) from where VAT was derived. We used descriptive analysis, correlations, receiver operating characteristics (ROC), and logistic regression to propose reference values for VAT and investigated VAT's association with cardiometabolic risk factors, MetS and single MetS components. Further, Youden's index was used to suggest threshold values for VAT. Results: VATg and VATindex increased until age 70 and then decreased, while VAT% increased with age across all age groups. VAT (all measurement units) was moderate to highly correlated and significantly associated with all cardiometabolic risk factors, except for total cholesterol. Associations between MetS, single MetS components, and VATg and VATindex were similar, and VAT% did not contribute any further to this association. Conclusion: These VAT reference values and thresholds, developed in a sample of adults of Norwegian origin, could be applied to other studies with similar populations using the same DXA device and protocols. The associations between VAT and cardiometabolic risk factors were similar across different measurement units of VAT.
... The few previous investigations examining the impact of overfeeding with RT have estimated the changes in body composition using dual-energy x-ray absorptiometry (DXA) [5,6], air displacement plethysmography (ADP) [7][8][9], hydrostatic weighing [4], and ultrasonography [2]. Although these methods are typically viewed as acceptable laboratory methods, they have notable limitations as compared to a criterion multi-component model, such as the 4-component (4C) model [10][11][12]. These limitations, such as assumptions about the density and hydration of FFM, have been documented to introduce potentially concerning levels of error in both the general population [13,14] and resistance-trained individuals [15,16]. ...
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Relatively few investigations have reported purposeful overfeeding in resistance-trained adults. This preliminary study examined potential predictors of resistance training (RT) adaptations during a period of purposeful overfeeding and RT. Resistance-trained males (n = 28; n = 21 complet-ers) were assigned to 6 weeks of supervised RT and daily consumption of a high-calorie protein/car-bohydrate supplement with a target body mass (BM) gain of ≥0.45 kg·wk −1. At baseline and post-intervention, body composition was evaluated via 4-component (4C) model and ultrasonography. Additional assessments of resting metabolism and muscular performance were performed. Accel-erometry and automated dietary interviews estimated physical activity levels and nutrient intake before and during the intervention. Bayesian regression methods were employed to examine potential predictors of changes in body composition, muscular performance, and metabolism. A simplified regression model with only rate of BM gain as a predictor was also developed. Increases in 4C whole-body fat-free mass (FFM; (mean ± SD) 4.8 ± 2.6%), muscle thickness (4.5 ± 5.9% for elbow flexors; 7.4 ± 8.4% for knee extensors), and muscular performance were observed in nearly all individuals. However, changes in outcome variables could generally not be predicted with precision. Bayes R 2 values for the models ranged from 0.18 to 0.40, and other metrics also indicated relatively poor predictive performance. On average, a BM gain of ~0.55%/week corresponded with a body composition score ((∆FFM/∆BM)*100) of 100, indicative of all BM gained as FFM. However, meaningful variability around this estimate was observed. This study offers insight regarding the complex interactions between the RT stimulus, overfeeding, and putative predictors of RT adaptations.
... There are several reasons why IMAT might partly be included in DXA's estimate of VAT. First, DXA can differentiate FM and lean fractions in areas where bone is not present [16,36]. In a whole-body scan, bones are present in 30e45% of the pixels [37,38]. ...
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Background & Aims Excess adipose tissue may affect colorectal cancer (CRC) patients’ disease progression and treatment. In contrast to the commonly used anthropometric measurements, Dual-Energy X-Ray Absorptiometry (DXA) and Computed Tomography (CT) can differentiate adipose tissues. However, these modalities are rarely used in the clinic despite providing high-quality estimates. This study aimed to compare DXA’s measurement of abdominal visceral adipose tissue (VAT) and fat mass (FM) against a corresponding volume by CT in a CRC population. Secondly, we aimed to identify the best single lumbar CT slice for abdominal VAT. Lastly, we investigated the associations between anthropometric measurements and VAT estimated by DXA and CT. Methods Non-metastatic CRC patients between 50-80 years from the ongoing randomized controlled trial CRC-NORDIET were included in this cross-sectional study. Corresponding abdominal volumes were acquired by Lunar iDXA and from clinically acquired CT examinations. Also, single CT slices at L2-, L3-and L4-level were obtained. Agreement between the methods was investigated using univariate linear regression and Bland-Altman plots. Results Sixty-six CRC patients were included. Abdominal volumetric VAT and FM measured by DXA explained up to 91% and 96% of the variance in VAT and FM by CT, respectively. Bland-Altman plots demonstrated an overestimation of VAT by DXA compared to CT (mean difference of 76 cm³) concurrent with an underestimation of FM (mean difference of -319 cm³). A higher overestimation of VAT (p=0.015) and underestimation of FM (p=0.036) were observed in obese relative to normal weight subjects. VAT in a single slice at L3-level showed the highest explained variance against CT volume (R²=0.97), but a combination of three slices (L2, L3, L4) explained a significantly higher variance than L3 alone (R²=0.98, p<0.006). The anthropometric measurements explained between 31-65 % of the variance of volumetric VAT measured by DXA and CT. Conclusions DXA and the combined use of three CT slices (L2-L4) are valid to predict abdominal volumetric VAT and FM in CRC patients when using volumetric CT as a reference method. Due to the poor performance of anthropometric measurements we recommend exploring the added value of advanced body composition by DXA and CT integrated into CRC care. Keywords: Visceral adipose tissue, Fat mass, Inter- and intramuscular adipose tissue, Dual-Energy X-ray Absorptiometry, Computed Tomography, colorectal cancer.
... Trotzdem sind die Ergebnisse und Auswirkungen dieser Analyse wichtig für weitere Forschung zu diesem Thema. Zukünftige Arbeiten werden dieses Modell in einer größeren, vielfältigeren Population testen.Obwohl die Verwendung der DEXA zur Beurteilung der Muskelmasse eines der am häufigsten verwendeten methodischen Instrumente ist(194), weist es jedoch inhärente Einschränkungen auf. DEXA ist kein tragbares Gerät und muss daher in einem Laborumfeld verwendet werden, was seinen Einsatz in vielen Kliniken stark einschränkt.Darüber hinaus verwendet DEXA die Strahlungstechnologie. ...
Thesis
Hintergrund und Ziele Ziel dieser Studie war es, einen Zusammenhang zwischen der Performance in den Funktionstests und der Muskelmasse der Arme und Beine zu finden, um die Vorher-sagefähigkeit für die Muskelschwäche dieser leicht durchführbaren Funktionstests ge-nauer beurteilen zu können. Die Muskelmasse wurde mittels Doppel-Röntgen-Absorptiometrie (DEXA) ermittelt, die Muskelkraft der unteren Extremitäten mittels Short Physical Performance Battery (SPPB). Diese umfasste den Gleichgewichttest, den 4m-Gangtest und den Stuhlauf-stehtest. Die körperliche Beurteilung beinhaltete außerdem die Handgriffstärke und den 400m-Gangtest. Sarkopenie wurde definiert unter Verwendung von appendikulärer Muskelmasse (ALM) (Männer < 19,75 kg; Frauen < 15,02 kg) und BMI-korrigierter Muskelmasse (ALM/BMI) (Männer < 0,789; Frauen < 0,512). Sarkopenische Adipositas wurde diagnostiziert, wenn Personen die Kriterien für Sarkopenie und Adipositas durch Körperfett erfüllten (Männer > 27%; Frauen > 38%). Die Prävalenzraten von Sarkopenie und sarkopenischer Adipositas wurden in Bezug auf das Geschlecht bewertet. Methode Die Stichprobe bestand aus 75 Männern (24,7%) und 229 Frauen (75,3%). Das Durch-schnittsalter der Männer lag bei 79,2 Jahren und das der Frauen bei 79,8 Jahren. Im Mittel hatten die Männer einen BMI von 30,13 kg/m2, während bei Frauen der durch-schnittliche BMI bei 29,8 kg/m2 lag. Bei Männern lag die Prävalenz der sarkopenischen Adipositas bei 54,7%. Im Vergleich dazu wurden 17,47% der Frauen (40/229) aufgrund ihrer unter dem Grenzwert reduzierten Muskelmasse als sarkopen eingestuft. 26 der 229 Frauen (11,3%) hatten eine sarkopenische Adipositas. In Bezug auf das Geschlecht waren deutlich mehr Männer (54,67%) von Sarkopenie betroffen als Frauen (28,82%). Dieser Unterschied war statistisch höchst signifikant (p < 001). Die mittlere Anzahl der Medikamente betrug 4,8 bei Frauen und 5,4 bei Männern. 46,6% der ProbandInnen berichteten über die regelmäßige Einnahme von ≥ 5 Medikamenten / Tag. Die meisten TeilnehmerInnen (88/302) hatten einen SPPB-Wert von 7 in einer Skala von 1 bis 12. Lediglich die sarkopenen Frauen zeigten eine statistisch signifikante Korrelation (p<0,05) zwischen dem SPPB-Score und der Beinmuskelmasse. Der Zusammenhang zwischen der Handgriffstärke und der Muskelmasse der Arme war bei beiden Ge-schlechtern höchst signifikant (p < 0,001). Bei Männern bestand ebenfalls eine höchst signifikante Korrelation zwischen der Handgriffstärke und der Beinmuskelmasse (p < 0,001). Die Verwendung der Cut-off-Werte der Handgriffstärke zur Diagnose einer Sarkopenie nach den Kriterien von Alley et al. (< 16 kg für Frauen; < 26 kg für Männer) ergab, dass 27,5% der Frauen (50/182) und 23,9% der Männer (16/67) als sarkopen einzustufen waren. Schlussfolgerung Die lineare Regressionsanalyse zeigte, dass die Variablen Geschlecht, Griffstärke und BMI eine höchst signifikante Korrelation mit der Arm- und Beinmuskelmasse aufwiesen (p<0,001). Die Subsets der SPPB (Balancezeit, 4m-Gangzeit und Stuhlaufstehzeit) kor-relierten ebenfalls sehr signifikant mit der Muskelmasse der Arme (p<0,01). Die Stuhlaufstehzeit zeigte eine höchst signifikante Korrelation mit der Beinmuskelmas-se (p<0,001) und eine hoch signifikante Korrelation mit der Armmuskelmasse (p<0,01). Somit reichen in dieser Studie die Variablen Griffstärke und Stuhlaufstehzeit für einen Schnelltest zur Abschätzung der Muskelmasse aus.
... As previously noted, the aforementioned studies have estimated alterations in lean/fat-free mass using DXA methodology: however, several limitations need to be taken into account when considering exercise training-induced changes in body composition using this approach. For example, the precision (trueness) of whole body lean mass measurements, as estimated from the coefficient of variation (CV) ranges from ~ 0.5 to 1% depending on the densitometer used [110]. Additionally, DXA cannot distinguish muscle from intramuscular fluid and is affected by hydration status [111,112]. ...
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Exercise training in combination with optimal nutritional support is an effective strategy to maintain or increase skeletal muscle mass. A single bout of resistance exercise undertaken with adequate protein availability increases rates of muscle protein synthesis and, when repeated over weeks and months, leads to increased muscle fiber size. While resistance-based training is considered the ‘gold standard’ for promoting muscle hypertrophy, other modes of exercise may be able to promote gains in muscle mass. High-intensity interval training (HIIT) comprises short bouts of exercise at or above the power output/speed that elicits individual maximal aerobic capacity, placing high tensile stress on skeletal muscle, and somewhat resembling the demands of resistance exercise. While HIIT induces rapid increases in skeletal muscle oxidative capacity, the anabolic potential of HIIT for promoting concurrent gains in muscle mass and cardiorespiratory fitness has received less scientific inquiry. In this review, we discuss studies that have determined muscle growth responses after HIIT, with a focus on molecular responses, that provide a rationale for HIIT to be implemented among populations who are susceptible to muscle loss (e.g. middle-aged or older adults) and/or in clinical settings (e.g. pre- or post-surgery).
... DXA-determined mass corresponded to gravimetric measures with high reliability during both measurement periods, both with a correlation coefficient of >0.99 for women and men and slopes ranging from 1.00 to 1.01. Coefficients of variation for DXA FM and % BF measurements have been previously reported to be <2% [12]. Fat mass index (FMI) was calculated from the DXA FM divided by the square of height, expressed as (kg m −2 ). ...
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U.S. Army Basic Combat Training (BCT) prepares new recruits to meet soldier physical demands. It also serves as a model of physical changes in healthy young nonobese women and men during an intensive 10-week training program without diet restriction. In this prospective observational study, we quantified the changes in lean mass and body fat induced by BCT in a large sample of men and women undergoing the same physical training program. Young women (n = 573) and men (n = 1071) meeting Army health and fitness recruitment standards volunteered to provide DXA-derived body composition data at the beginning and end of BCT. During BCT, there was no change in body mass in women and a 1.7-kg loss in men. Relative body fat (%BF) declined by an average of 4.0 ± 2.4 and 3.4 ± 2.8 percentage points (±SD) for women and men, respectively. The greatest predictor of change in %BF during BCT for both sexes was %BF at the beginning of training. Women and men gained an average 2.7 ± 1.6 kg and 1.7 ± 2.0 kg of lean mass during BCT. Army BCT produced significant effects on body composition despite minimal changes in total body mass. These findings demonstrate the ability of a 10-week sex-integrated physical training program to positively alter body composition profiles of young adults.
... On this subject, LaForgia and collaborators [19] indicate that DXA may provide reasonable cross-description data for obese cohorts. Also, DXA has been employed as the "gold standard" research method for body composition analysis, and it seems to be a reliable method to estimate total and regional BF featuring improved feasibility, high accuracy, and reproducibility [20,21,47]. One major limitation of our study is that cut-off points were based on the North American population because there are no cut-off points established for the Brazilian population. ...
Article
Background and aim Relative fat mass (RFM) is a new method to estimate whole-body fat percentage in adults using an anthropometric linear equation. We aimed to assess the association between RFM and body fat (BF), evaluated by dual x-ray absorptiometry (DXA) or bioelectrical impedance (BIA), in young male adults. Methods Eighty-one young males were assessed for BF fat and free fat mass (by BIA and DXA), waist circumference. BMI and RFM were then calculated from data collected from the subjects. The agreement between BMI and RFM or BIA/DXA was assessed by Pearson's Correlation and Kappa index. Univariate and multivariate linear regression were applied. Results Analyzing all the participants together, the correlation between RFM and DXA (rDXA = 0.90) or RFM and BIA (rBIA = 0.88) were slightly higher than the correlation between BMI and DXA (rDXA = 0.79) or BMI and BIA (rBIA: 0.82). When analyzed by BF, low BF (LBF) individuals showed a much higher correlation with RFM (rDXA = 0.58; rBIA = 0.73) than BMI (rDXA = 0.24; rBIA: 0.46). However, subjects with excess BF (EBF) presented similar correlations when comparing RFM (rDXA = 0.80; rBIA = 0.64) and BMI (rDXA = 0.78; rBIA = 0.64). In general, RFM presented a higher strength of agreement with DXA and BIA (kDXA = 0.75; kBIA = 0.67) than BMI (kDXA = 0.63; kBIA = 0.60). Multivariable linear regression also revealed high associations between RFM and DXA or RFM and BIA (r²DXA = 0.85; r²BIA = 0.81). Conclusion Our findings suggest that RFM shows a good correlation and association with BF measured by DXA and BIA in young male adults. Furthermore, RFM seems to be better correlated to BF in LBF individuals when compared to BMI. Therefore, further studies investigating RFM as a tool to assess BF and obesity are motivated.
... This may have been due to the later version of software (encore 16) being used in our analysis on both scanners. The technical differences between the two models of GE Lunar has been previously discussed (4,23). In brief, the main differences between the scanners are a change in the detector and X-ray filter, within the iDXA which provide an improved resolution and image quality, resulting in an enhancement of the bone edge detection technology. ...
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Background Body composition is associated with many non-communicable diseases. The accuracy of many simple techniques used for the assessment of body composition is influenced by the fact that they do not take into account tissue hydration and this can be particularly problematic in paediatric populations. Objectives The aims of this study were: 1) to assess the agreement of two dual energy X-ray absorptiometry (DXA) systems for determining total and regional (arms, legs, trunk) fat, lean and bone mass and 2) to compare lean soft tissue (LST) hydration correction methods in children. Design One hundred and twenty four healthy children aged between 6 and 16 years old underwent DXA scans using two GE healthcare Lunar systems (iDXA and Prodigy). Tissue hydration was either calculated by dividing total body water (TBW), by four-component model derived fat free mass (HFFMTBW) or by using the age and sex specific coefficients of Lohman, 1986 (HFFMLohman) and used to correct LST. Regression analysis was performed to develop cross-calibration equations between DXA systems and a paired samples t-test was conducted to assess the difference between LST hydration correction methods. Results iDXA resulted in significantly lower estimates of total and regional fat and lean mass, compared to Prodigy. HFFMTBW showed a much larger age/sex related variability than HFFMLohman. A 2.0 % difference in LST was observed in the boys (34.5 kg vs. 33.8 kg respectively, P<0.05) and a 2.5% difference in the girls (28.2 kg vs. 27.5 kg respectively, P<0.05) when corrected using either HFFMTBW or HFFMLohman. Conclusions Care needs to be exercised when combining data from iDXA and Prodigy, as total and regional estimates of body composition can differ significantly. Furthermore, tissue hydration should be taken into account when assessing body composition as it can vary considerably within a healthy paediatric population even within specific age/sex groups.
... Dual-energy X-ray Absorptiometry [DXA] can rapidly quantify body composition in vivo using a three-compartment model, separating scanned body tissues into fat, lean mass and bone (Albanese et al, 2003). Whilst a more accurate four-compartment model exists (Toombs et al, 2012), accessing and performing the additional battery of tests required to achieve this prohibited its use within this project. All Phase I participants underwent one full-body DXA scan [Lunar Prodigy Advance; GE Healthcare] to determine body composition. ...
... The present study also supports the robustness of DXA in less-than-ideal standardisation conditions, with this technology arguably demonstrating the best overall performance in the context of the present study. Although DXA has limitations when compared with criterion multi-component models (12,37,58) , the present results demonstrate an advantage of DXA in unstandardised conditions and indicate that the use of multi-component models should be restricted to standardised conditions. The cumulative error introduced by the multiple input terms within a 4C model -BM, BV, TBW and Molikely all make contributions to the errors observed in unstandardised conditions, although the influence of TBW may be particularly large. ...
Article
The present study reports the validity of multiple assessment methods for tracking changes in body composition over time and quantifies the influence of unstandardized pre-assessment procedures. Resistance-trained males underwent 6 weeks of structured resistance training alongside a hypercaloric diet, with four total body composition evaluations. Pre-intervention, body composition was estimated in standardized (i.e., overnight fasted and rested) and unstandardized (i.e., no control over pre-assessment activities) conditions within a single day. The same assessments were repeated post-intervention, and body composition changes were estimated from all possible combinations of pre-intervention and post-intervention data. Assessment methods included dual-energy X-ray absorptiometry (DXA), air displacement plethysmography, 3-dimensional optical imaging, single- and multi-frequency bioelectrical impedance analysis, bioimpedance spectroscopy, and multi-component models. Data were analyzed using equivalence testing, Bland-Altman analysis, Friedman tests, and validity metrics. Most methods demonstrated meaningful errors when unstandardized conditions were present pre- and/or post-intervention, resulting in blunted or exaggerated changes relative to true body composition changes. However, some methods – particularly DXA and select digital anthropometry techniques – were more robust to a lack of standardization. In standardized conditions, methods exhibiting the highest overall agreement with the 4-component model were other multi-component models, select bioimpedance technologies, DXA, and select digital anthropometry techniques. Although specific methods varied, the present study broadly demonstrates the importance of controlling and documenting standardization procedures prior to body composition assessments across distinct assessment technologies, particularly for longitudinal investigations. Additionally, there are meaningful differences in the ability of common methods to track longitudinal body composition changes.
... A limitation of this study is that the DXA scanner used to estimate body composition (GE Lunar DPX Pro) has been superseded by newer models with enhanced precision. PE from the DPX estimations has been found to be twice as high as the GE Lunar Prodigy in athletes (Bilsborough et al., 2014), whereas the iDXA model resolution has improved bone edge detection, thus allowing for superior algorithms for body composition estimation (Toombs et al., 2011). ...
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Athletic populations require high-precision body composition assessments to identify true change. Least significant change determines technical error via same-day consecutive tests but does not integrate biological variation, which is more relevant for longitudinal monitoring. The aim of this study was to assess biological variation using least significant change measures from body composition methods used on athletes, including surface anthropometry (SA), air displacement plethysmography (BOD POD), dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance spectroscopy (BIS). Thirty-two athletic males (age = 31 ± 7 years; stature = 183 ± 7 cm; mass = 92 ± 10 kg) underwent three testing sessions over 2 days using four methods. Least significant change values were calculated from differences in Day 1 Test 1 versus Day 1 Test 2 (same-day precision), as well as Day 1 Test 1 versus Day 2 (consecutive-day precision). There was high agreement between same-day and consecutive-day fat mass and fat-free mass measurements for all methods. Consecutive-day precision error in comparison with the same-day precision error was 50% higher for fat mass estimates from BIS (3,607 vs. 2,331 g), 25% higher from BOD POD (1,943 vs. 1,448 g) and DXA (1,615 vs. 1,204 g), but negligible from SA (442 vs. 586 g). Consecutive-day precision error for fat-free mass was 50% higher from BIS (3,966 vs. 2,276 g) and SA (1,159 vs. 568 g) and 25% higher from BOD POD (1,894 vs. 1,450 g) and DXA (1,967 vs. 1,461 g) than the same-day precision error. Precision error in consecutive-day analysis considers both technical error and biological variation, enhancing the identification of small, yet significant changes in body composition of resistance-trained male athletes. Given that change in physique is likely to be small in this population, the use of DXA, BOD POD, or SA is recommended.
... Dual-energy x-ray absorptiometry (DXA) is one of the gold standard methods for body composition measurement (Andreoli et al. 2009;Kerr et al. 2017;Day et al. 2018). It measures both total and regional body composition components accurately (Toomey et al. 2017), and is widely used in sedentary individuals and athletes to evaluate health status, physical profile, and training effects (Toombs et al. 2012;Meyer et al. 2013;Nana et al. 2015;Midorikawa et al. 2018). Among the studies examining whole body composition changes during the menstrual cycle, only one reported DXAderived results (Hicks et al. 2017), with the remaining studies reporting single or multi-frequency bioelectric impedance (BIA) results (Gualdi-Russo and Toselli 2002; Cumberledge et al. 2018;Dokumacı and Hazır 2019;Rael et al. 2021). ...
Article
Background: Changes in estradiol and progesterone hormones and associated fluid retention during the menstrual cycle phases might affect body composition (BC) in women. Aim: The main objectives of this study were to determine the changes in whole and regional BC by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance (BIA) during the mid-follicular (MFP) and mid-luteal (MLP) phases. Subjects and methods: Thirty recreationally active young women participated in this study. BC was measured by DXA and BIA during MFP and MLP. A mixed linear model for repeated measures analysis was used to determine the differences between the two phases. Results: Body mass was higher during MLP than MFP, while total body water, total and segmental fat mass and fat percentages measured by both BIA and DXA were similar during the two phases. DXA-derived fat-free mass and soft lean mass in the android region were higher during MLP than MFP. Large variability in individual responses was evident. Conclusion: On average, whole and segmental BC variables do not change significantly between MFP and MLP. However, given the large variability among the individual responses, it is suggested to perform repeated BC measurements during the same phase of the menstrual cycle.
... The following were assessed in the 87 included patients at inclusion in the study, i.e. after a median disease duration of 15 months (range 11-30 months): total fat, lean mass, and fat mass distribution were examined with dual-energy X-ray absorptiometry (DXA; Lunar Prodigy X-ray Tube Housing Assembly, Brand BX-11, Model 8743; GE Medical Systems, Madison, WI, USA) (16). The percentage of fat-free mass was calculated by dividing the fat-free mass (g) by the total mass (g). ...
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Objective Rheumatoid cachexia (RC) is prevalent among patients with established rheumatoid arthritis (RA). Although changes in muscle mass and fat mass have been reported in early RA, these findings have not been classified according to existing RC definitions. This study aimed to describe the prevalence of RC and associated variables in patients with early RA. Method This cross-sectional study included 87 patients. Body composition was evaluated with dual-energy X-ray absorptiometry after a median disease duration of 15 months. RC was defined as a fat-free mass index < 10th percentile and fat mass index > 25th percentile. We also assessed the erythrocyte sedimentation rate (ESR), C-reactive protein, Disease Activity Score in 28 joints, aerobic capacity, physical activity, traditional cardiovascular disease risk factors, functional disability, and sociodemographic data. Associations between RC and the independent variables were determined with logistic regression analyses. Results The prevalence of RC was 24%. RC was significantly associated [odds ratio (95% confidence interval)] with aerobic capacity [0.28 (0.09–0.89), p = 0.030], low-intensity physical activity [0.77 (0.60–0.99), p = 0.048], body mass index [0.78 (0.70–0.92), p = 0.002], waist circumference [0.96 (0.92–0.99), p = 0.023], body weight [0.94 (0.90–0.98), p = 0.004], and ESR at the time of diagnosis [1.02 (1.00–1.05), p = 0.033]. All of these associations remained significant after adjusting for age and gender. Conclusion RC was highly prevalent in early RA. Patient outcome may be improved by detecting this condition early and applying treatments for improving inflammation, aerobic capacity, physical activity, and body composition.
... Participants produced a negative pregnancy test prior to scanning procedures. In vivo coefficient of variation for soft tissue and %BFDXA is 0.4 to 1.0% (11). Manual circumference measurements at the neck, waist and hips were made in triplicate using a calibrated fiberglass tape measure and recorded to the nearest 0.1 cm to estimate %BFCIRC using the Hodgdon equation for women (12); this is the DoD standard for female body composition measurement (10). ...
Article
Introduction: This study characterized a sample of the first women to complete elite United States (US) military training. Methods: Twelve female graduates of the US Army Ranger Course and one of the first Marine Corps Infantry Officers Course graduates participated in three days of laboratory testing including serum endocrine profiles, aerobic capacity, standing broad jump (SBJ), common soldiering tasks, Army Combat Fitness Test (ACFT), and body composition (DXA, 3D body surface scans, and anthropometry). Results: The women were 6 mo to 4 y post-course graduation, 30 ± 6 y (mean ± SD), height 1.67 ± 0.07 m, body mass 69.4 ± 8.2 kg, BMI 25.0 ± 2.3 kg·m-2. DXA relative fat was 20.0 ± 2.0%; fat-free mass (FFM) 53.0 ± 5.9 kg; fat-free mass index (FFMI) 20.0 ± 1.7 kg·m-2; bone mineral content 2.75 ± 0.28 kg; bone mineral density 1.24 ± 0.07 g·cm-2; aerobic capacity 48.2 ± 4.8 mL·kg-1·min-1; total ACFT score 505 ± 27; SBJ 2.0 ± 0.2 m; 123 kg casualty drag 0.70 ± 0.20 m·s-1, and 4 mile 47 kg ruck march 64 ± 6 min. All women were within normal healthy female range for circulating androgens. Physique from 3D scan demonstrated greater circumferences at eight out of the eleven sites compared to the standard military female. Conclusions: These pioneering women possessed high strength and aerobic capacity, low %BF; high FFM, FFMI, and bone mass and density; and they were not virilized based on endocrine measures as compared to other reference groups. This group is larger in body size and leaner than the average Army woman. These elite physical performers seem most comparable to female competitive strength athletes.
... Despite DXA being widely deemed a gold standard method for body composition analyses due to its accuracy and repeatability (Demmer et al., 2016;Toombs et al., 2012), the method is not without its limitations. Firstly, our findings suggest the possible role that increased FM may have had over the course of the competitive season. ...
Article
Background: Reference data for the body composition values of female athletes are limited to very few sports, with female Rugby Union players having mostly been omitted from such analyses. Methods: Using dual energy X-ray absorptiometry (DXA) scans, this study assessed the body composition profiles (body mass, bone mineral content; BMC, fat mass; FM, lean mass; LM, bone mineral density; BMD) of 15 competitive female Rugby Union players before and after the 2018/19 competitive season. Total competitive match-play minutes were also recorded for each player. Results: Body mass (73.7±9.6 kg vs 74.9±10.2 kg, p≤0.05, d=0.13) and BMC (3.2±0.4 kg vs 3.3±0.4 kg, p≤0.05, d=0.15) increased pre-to post-season for all players. Conversely, FM (21.0±8.8 kg), LM (50.7±3.9 kg), and BMD (1.31±0.06 g·cm-2) were similar between time-points (all p>0.05). Accounting for position, body mass (rpartial(12) = 0.196), FM (rpartial(12) =-0.013), LM (rpartial(12) = 0.351), BMD (rpartial(12) = 0.168) and BMC (rpartial(12) =-0.204) showed no correlation (all p>0.05) against match-play minutes. Conclusion: The demands of the competitive season influenced specific body composition indices (i.e., body mass, BMC) in female Rugby Union players; a finding which was unrelated to the number of minutes played in matches. While the causes of such differences remain unclear, practitioners should be cognisant of the body composition changes occurring throughout a female Rugby Union competitive season and, where necessary, consider modifying variables associated with adaptation and recovery accordingly.
... Although DXA has become the gold standard for bone mass, it has been suggested as a reference for the soft tissue assessment of fat mass and percentage body fat [38]. However, the differences between devices, manufacturers and software versions can lead to divergent results [39]. ...
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Combat sports athletes competing in the same discipline exhibit notable and substantial differences in body weight, body composition (BC) and adiposity. No studies have considered the influence of adiposity levels in the agreement between different BC assessment methods. The aim of this study was to analyze the influence of adiposity in the agreement between different methods used to estimate relative body fat (%BF) in Olympic combat sport athletes. A total of 38 male athletes were evaluated using air displacement plethysmography and dual-energy X-ray absorptiometry (DXA) as laboratory methods, and bioelectrical impedance analysis (BIA), near-infrared interactance (NIR) and anthropometry as field methods. All methods were compared to DXA. Agreement analyses were performed by means of individual intraclass correlation coefficients (ICCs) for each method compared to DXA, Bland–Altman plots and paired Student t-tests. The ICCs for the different methods compared to DXA were analyzed, considering tertiles of %BF, tertiles of body weight and type of sport. For the whole group, individual ICCs oscillated between 0.806 for BIA and 0.942 for anthropometry. BIA showed a statistically significant underestimation of %BF when compared to DXA. The agreement between every method and DXA was not affected by %BF, but it was highest in athletes at the highest %BF tertile (>13%). The ICC between NIR and DXA was poor in 72–82 kg athletes. Our results indicate that field methods are useful for routine %BF analysis, and that anthropometry is particularly appropriate, as it showed the highest accuracy irrespective of the athletes’ adiposity.
... Reproducibility of this estimate between experienced observers is ±1% body fat units (Hodgdon and Friedl, 1999). Body composition was assessed by DXA (iDXA, GE Healthcare, Madison, WI) and data analysis relied on manufacturer supplied algorithms (Encore, version 13.5, Lunar Corp., Madison, WI) (Mazess et al., 1990;Toombs et al., 2012;Lukaski, 2017). At the end of the DXA scan each volunteer remained in a relaxed supine position, on a nonconductive pad overlaying the wooden DXA platform, and total body resistance was measured at 50 KHz between left hand and left foot (Quantum IV, RJL Systems, Clinton Township, MI) and total body water (TBW) and body fat (%BF BIA) were calculated using the equations of Sun et al. (Sun et al., 2003). ...
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Purpose: Body composition assessment methods are dependent on their underlying principles, and assumptions of each method may be affected by age and sex. This study compared an abdominal circumference-focused method of percent body fat estimation (AC %BF) to a criterion method of dual-energy x-ray absorptiometry (DXA), and a comparative assessment with bioelectrical impedance (BIA), in younger (≤30 years) and older (>age 30 years) physically fit (meeting/exceeding annual US Marine Corps fitness testing requirements) men and women. Methods: Fit healthy US Marines (430 men, 179 women; 18–57 years) were assessed for body composition by DXA (iDXA, GE Lunar), anthropometry, and BIA (Quantum IV, RJL Systems). Results: Compared to DXA %BF, male AC %BF underestimated for both ≤30 and >30 years age groups (bias, -2.6 ± 3.7 and -2.5 ± 3.7%); while female AC %BF overestimated for both ≤30 and >30 years age groups (2.3 ± 4.3 and 1.3 ± 4.8%). On an individual basis, lean men and women were overestimated and higher %BF individuals were underestimated. Predictions from BIA were more accurate and reflected less relationship to adiposity for each age and sex group (males: ≤30, 0.4 ± 3.2, >30 years, -0.5 ± 3.5; women: ≤30, 1.4 ± 3.1, >30 years, 0.0 ± 3.3). Total body water (hydration) and bone mineral content (BMC) as a proportion of fat-free mass (FFM) remained consistent across the age range; however, women had a higher proportion of %BMC/FFM than men. Older men and women (>age 30 years) were larger and carried more fat but had similar FFM compared to younger men and women. Conclusion: The AC %BF provides a field expedient method for the US Marine Corps to classify individuals for obesity prevention, but does not provide research-grade quantitative body composition data.
... En effet, les images dans les zones affichant l'os ne permettent à la DXA que de faire la distinction entre l'os et les tissus mous comme la masse maigre (MM) et la masse grasse (MG) (Toombs et al., 2012). De plus, il existe une difficulté lors de l'utilisation de DXA d'évaluer la graisse abdominale chez les personnes obèses (Bredella et al., 2010 (Kullberg et al., 2009 ;Messina et al., 2018). ...
Thesis
Le premier objectif de cette thèse de doctorat était de comparer la densité minérale osseuse (DMO) et les indices géométriques de résistance osseuse de la hanche chez des sujets âgés ayant un indice de masse maigre squelettique (SMI) normal et des sujets âgés sarcopéniques. Le deuxième objectif était d’explorer les relations entre la force maximale des membres inférieurs et supérieurs et la densité minérale osseuse chez des sujets âgés ayant un faible SMI. Pour ce faire, trois études ont été menées. La première étude a démontré que la sarcopénie est associée à une diminution de la DMO de la hanche totale et des indices géométriques de résistance osseuse de la hanche chez les femmes âgées. La deuxième étude a démontré que la sarcopénie est associée à une diminution du contenu minéral osseux (CMO), de la DMO et des indices géométriques de résistance osseuse de la hanche chez les hommes âgés. La troisième étude a démontré que la force maximale des membres inférieurs et supérieurs est positivement corrélée à la DMO de la hanche totale chez les sujets âgés ayant un faible SMI. En conclusion, l’optimisation de la masse maigre et de la force maximale des membres inférieurs et supérieurs semble pertinente pour la prévention de l’ostéoporose chez les personnes âgées ayant un faible SMI.
... 57 In contrast, DXA uses X-ray attenuation by different tissues to estimate body composition and its accuracy can be influence by body size. 58 Therefore, in populations with obesity, differences in total body water levels and body composition (e.g., greater tissue depth) may decrease the accuracy of body fat and fat-free mass estimates. 57 There were two types of DXA machines (GE/Lunar and Hologic) that were utilized by our included studies, and while DXA is not considered a gold-standard measurement for body composition, it is widely recommend due to its high precision, low cost, and wide availability. ...
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To determine relative lean mass and fat mass changes in adults with obesity following surgical weight loss interventions, a systematic review and meta‐analysis was conducted. The Cochrane Central Register of Controlled Trials, PubMed, Web of Science, EMBASE, and Scopus were screened for eligible studies. Inclusion criteria included randomized controlled trials (RCTs) performed in populations with obesity (body mass index ≥30 kg/m2) aged over 18 years, who underwent any type of bariatric surgery and reported body composition measures via dual‐energy X‐ray absorptiometry or bio‐electrical impedance analysis. Authors conducted full text screening and determined that there were six RCTs eligible for inclusion, with data extracted at 12 months post‐surgery. Meta‐analysis revealed that, relative to gastric banding, Roux‐en‐Y gastric bypass (RYGB) led to greater total body mass loss (mean difference [MD]: −9.33 kg [95% CI: −12.10, −6.56]) and greater fat mass loss (MD: −8.86 kg [95% CI: −11.80, −5.93], but similar lean mass loss (MD: −0.55 kg [95% CI: −3.82, 2.71]. RYGB also led to similar changes in total body mass, fat mass, and lean mass compared with sleeve gastrectomy. RYGB results in greater 12‐month weight and fat loss, but similar changes in lean mass, compared with gastric banding. Further RCTs comparing body composition changes following different bariatric surgery procedures are required.
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Whilst the assessment of body composition is routine practice in sport, there remains considerable debate on the best tools available, with the chosen technique often based upon convenience rather than understanding the method and its limitations. The aim of this manuscript was threefold: 1) provide an overview of the common methodologies used within sport to measure body composi-tion, specifically hydro-densitometry, air displacement plethysmography, bioelectrical imped-ance analysis and spectroscopy, ultra-sound, three dimensional scanning, dual-energy x-ray ab-sorptiometry (DXA) and skinfold thickness; 2) compare the efficacy of what are widely believed to be the most accurate (DXA) and practical (skinfold thickness) assessment tools and 3) provide a framework to help select the most appropriate assessment in applied sports practice including insights from the authors’ experiences working in elite sport. Traditionally, skinfold thickness has been the most popular method of body composition but in recent years the use of DXA has in-creased, with a wide held belief that it is the criterion standard. When bone mineral content needs to be assessed, and/or when it is necessary to take limb specific estimations of fat and fat free mass, then DXA appears to be the preferred method; although it is crucial to be aware of the logis-tical constraints required to produce reliable data, including controlling food intake, prior exer-cise and hydration status. However, given the need for simplicity and after considering the evi-dence across all assessment methods, skinfolds appear to be the least affected by day-to-day var-iability, leading to the conclusion ‘come back skinfolds, all is forgiven’.
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Background & aims Although previous research show high correlation between fat-free mass (FFM) measured by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA), the validity of BIA to track longitudinal changes in FFM is uncertain. Thus, the aim of this study was to validate the ability of BIA to assess changes in FFM during 6 months of recovery from non-metastatic colorectal cancer (CRC). Methods A total of 136 women and men (50–80 years) with stage I-III CRC and a wide range of baseline FFM (35.7–73.5 kg) were included in the study. Body composition was measured at study baseline within 2–9 months of surgery and again 6 months later. Whole-body BIA FFM estimates (FFMBIA) were calculated using three different equations (manufacturer's, Schols' and Gray's) before comparison to FFM estimates obtained by DXA (FFMDXA). Results Correlation between changes in FFMBIA and FFMDXA was intermediate regardless of equation (r ≈ 0.6). The difference in change of FFMBIA was significant compared to FFMDXA, using all three equations and BIA overestimated both loss and gain. However, BIA showed 100% sensitivity and about 90% specificity to identify individuals with ≥5% loss in FFM, using all three equations. Sensitivity of FFMBIA to detect a smaller loss of FFM (60–76%) or a gain in FFM of ≥5% (33–62%) was poor. Conclusion In a well-nourished population of non-metastatic CRC patients, a single-frequency whole-body BIA device yielded imprecise data on changes in FFM, regardless of equation. BIA is thus not a valid option for quantifying changes in FFM in individuals. However, BIA could be used to identify patients with loss in FFM ≥5% in this population. The validity of BIA to monitor changes in FFM warrants further investigation before implementation in clinical praxis.
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Although the impact of obesity on exercise performance is multifactorial, excessive fat mass which can impose an unfavorable burden on cardiac function and working muscle, will affect the aerobic exercise capacity. Weight loss strategies, such as bariatric surgery can obviously affect both the body composition and aerobic exercise capacity. Maximal oxygen consumption (V̇O2max) is a widely used important indicator of aerobic exercise capacity of an individual and is closely related to body weight, size and composition. An individual’s aerobic exercise capacity may show different results depending on how V̇O2max is expressed. The absolute V̇O2max and V̇O2max relative to body weight are the most commonly used indicators. The V̇O2max relative to fat-free mass, lean body mass or skeletal muscle mass are not influenced by adipose tissue. The last two are more useful to precisely distinguish between individuals differing in muscle adaptation to maximum oxygen uptake. The V̇O2max relative to body height is used for studying growth in children. With the in-depth study of exercise capacity and body composition in obesity, the relative oxygen uptake has been increasingly reinterpreted.
Article
Introduction/background We performed this study to enable a reliable transition for clinical study participants and patients from a GE Lunar Prodigy to a Hologic Horizon A dual-energy X-ray absorptiometry (DXA) scanner and to assess the reproducibility of measurements made on the new DXA scanner. Methodology Forty-five older adults had one spine, hip and total body scan on a Prodigy dual-energy X-ray absorptiometry (DXA) scanner and two spine, hip, and total body scans, with repositioning, on a new Hologic Horizon A DXA scanner. Linear regression models were used to derive cross calibration equations for each measure on the two scanners. Precision (group root-mean-square average coefficient of variation) of bone mineral density (BMD) of the total hip, femoral neck, and lumbar spine (L1-L4), and total body fat, bone, and lean mass, appendicular lean mass, and trabecular bone score (TBS) was assessed using the International Society of Clinical Densitometry's (ISCD's) Advanced Precision Calculation Tool. Results Correlation coefficients for the BMD and body composition measures on the two scanners ranged from 0.94 to 0.99 (p<0.001). When compared with values on the Prodigy, mean BMD on the Horizon A was lower at each skeletal site (0.136 g/cm² lower at the femoral neck and 0.169 g/cm² lower at the lumbar spine (L1-4)), fat mass was 0.47 kg lower, and lean mass was 4.50 kg higher. Precision of the Horizon A scans was 1.60% for total hip, 1.94% for femoral neck, and 1.25% for spine (L1-4) BMD. Precision of TBS was 1.67%. Precision of total body fat mass was 2.16%, total body lean mass was 1.26%, appendicular lean mass was 1.97%, and total body bone mass was 1.12%. Conclusions The differences in BMD and body composition values on the two scanners illustrate the importance of cross-calibration to account for these differences when transitioning clinical study participants and patients from one scanner to another.
Article
Aim: To understand the anthropometry, metabolism, and menstrual status of Japanese collegiate female long-distance runners. Methods: This was a cross-sectional study of 29 Japanese college female long-distance runners divided into three menstruation status groups: 1) Regular; 2) Irregular; and 3) Amenorrhea. The amenorrhea group was further divided into participants who consulted a gynecologist and those who did not. Metabolism was measured using resting metabolic rate, total energy expenditure, and physical activity level. Energy was measured using energy intake, exercise energy expenditure, and energy availability (EA). Anthropometric measurements were performed following standardized techniques from the International Society for the Advancement of Kinanthropometry. Results: Of the 29 runners, 68% had menstrual dysfunction. The amenorrhea group who had consulted a gynecologist had lower body mass index (BMI) and lower skinfolds than the other groups. All groups had more than 30 kcal/kg fat free mass/day for EA with no difference between the groups. Conclusions: There was high prevalence of menstrual dysfunction in the female Japanese college long-distance runners. Runners with amenorrhea had lower BMI and lower skinfolds than the other groups, despite having consulted a gynecologist for medical support. All the runners had an energy deficiency higher than the published threshold; therefore, this threshold did not differentiate the amenorrhea or irregular menstruating athletes from regular menstruating athletes. Longitudinal tracking of athletes should include measurement of height, body mass, and skinfolds to enable evaluation of BMI, the sum of eight skinfold sites, and leanness ratio score as possible indicators over time for menstrual dysfunction.
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Background The Department of Defense circumference method (CM) is used to estimate percent body fat (%BF) in evaluation of health, physical fitness, appearance, and military readiness; however, the CM has not been validated in individuals with lower limb loss. Objective To evaluate the agreement between CM and dual-energy X-ray absorptiometry (DXA) for measuring %BF in individuals with lower limb loss. Design This study is part of a larger cross-sectional comparison study, and this analysis was included as a secondary objective. Two methods of measuring %BF included CM and DXA, with DXA as the reference standard for this study. Participants/setting This study was conducted at Walter Reed Army Medical Center. Data were collected from summer 2010 to summer 2011. One hundred individuals, 50 with and 50 without lower limb loss, were screened for this study; three individuals with limb loss and two without limb loss had incomplete data, and one individual (female, without limb loss) lacked a comparison participant. All participants were recruited from a military medical center, and data were collected in a clinic research laboratory. Main outcome measures Measurements of %BF were compared between methods for each group. Statistical analyses performed Measurements of %BF were compared using paired t-tests and intraclass correlation coefficient. Agreement and bias were assessed with Bland-Altman analysis. Receiver operating characteristic analysis was used to determine the diagnostic accuracy of the CM to identify participants with %BF levels in the obese category (≥25%). Results A statistically significant difference was found between %BF methods in the group with limb loss (1.7%; P = 0.001) and the group without limb loss (1.4%; P = 0.005), with DXA consistently higher than CM. However, the intraclass correlation coefficient estimates for the agreement between %BF by CM and DXA were 0.848 (95% confidence interval [CI]: 0.683–0.922; P < 0.001) and 0.828 (CI: 0.679–0.906; P < 0.001), for the groups with and without limb loss, respectively, suggesting that CM has good to near excellent agreement with DXA for estimating %BF in these groups. Receiver operating characteristic analysis indicated that the area under the curve supported predictive ability to detect obesity-based %BF in males with and without limb loss. Conclusions Although a statistically significant difference was found between methods for individuals with limb loss, there was also good agreement between the methods, suggesting that CM may be a useful tool for estimating %BF in individuals with lower limb loss. The CM may be a useful and field expedient method for assessing %BF in a clinical setting when DXA is not available.
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A densitometria óssea (DO) é o método de escolha e o mais amplamente usado, acurado e preciso para avaliação quantitativa da densidade mineral óssea (DMO), diagnóstico e rastreamento de baixa massa óssea para idade/osteopenia/osteoporose, bem como identificação de indivíduos com maior risco de fratura por fragilidade e monitorização da massa óssea, relacionada à própria doença ou ao tratamento instituído. Assim, esta revisão se propõe a discutir as peculiaridades técnicas da metodologia, bem como enumerar os detalhes da aquisição, análise e problemas/artefatos envolvidos com a interpretação clínica do exame. Unitermos: Densitometria óssea. Aquisição. Análise. Osteoporose. Composição corporal. Interpretação clínica.
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We aimed to comprehensively evaluate the association of body composition with fracture risk using longitudinal data from a Swedish cohort of 44 366 women and men (mean age of 70 years) and a subcohort of 5022 women. We estimated hazard ratios (HRs) of fracture for baseline body mass index (BMI), BMI change during the prior 18 years, baseline waist‐to‐height ratio, total and regional distribution of fat and lean mass, with and without areal bone mineral density (BMD) adjustment. During follow‐up (median 9 years), 7290 individuals sustained a fracture, including 4279 fragility fractures, of which 1813 were hip fractures. Higher baseline BMI and prior gain in BMI were inversely associated with all types of fracture. Lower fracture rate with higher baseline BMI was seen within every category of prior BMI change, whereas higher prior BMI gain conferred a lower rate of fracture within those with normal baseline BMI. Each SD higher baseline waist‐to‐height ratio, after adjustment for BMI, was associated with higher rates of hip fracture in both women and men (HR 1.12, 95% CI 1.05‐1.19). In the subcohort (median follow‐up 10 years), higher baseline fat mass index (FMI) and appendicular lean mass index (LMI) showed fracture‐protective effects. After BMD‐adjustment, higher baseline BMI, total LMI, FMI, and higher prior BMI gain were associated with higher fracture rate. Baseline fat distribution also was associated with fracture rate; a one SD higher android to gynoid fat mass ratio in prior BMI gainers was associated with BMD‐adjusted HRs of 1.16 (95% CI 1.05‐1.28) for any fracture and 1.48 (95% CI 1.16‐1.89) for hip fracture. This pattern was not observed among prior BMI losers. These findings indicate that for optimal fracture prevention, low baseline BMI, prior BMI loss and high baseline central obesity should be avoided in both women and men. This article is protected by copyright. All rights reserved.
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Objective To review the technical aspects of body composition assessment by dual-energy X-ray absorptiometry (DXA) and other methods based on the most recent scientific evidence. Materials and methods This Official Position is a result of efforts by the Scientific Committee of the Brazilian Association of Bone Assessment and Metabolism ( Associação Brasileira de Avaliação Óssea e Osteometabolismo , ABRASSO) and health care professionals with expertise in body composition assessment who were invited to contribute to the preparation of this document. The authors searched current databases for relevant publications. In this first part of the Official Position, the authors discuss the different methods and parameters used for body composition assessment, general principles of DXA, and aspects of the acquisition and analysis of DXA scans. Conclusion Considering aspects of accuracy, precision, cost, duration, and ability to evaluate all three compartments, DXA is considered the gold-standard method for body composition assessment, particularly for the evaluation of fat mass. In order to ensure reliable, adequate, and reproducible DXA reports, great attention is required regarding quality control procedures, preparation, removal of external artifacts, imaging acquisition, and data analysis and interpretation.
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Purpose We determined associations between adipokines and abnormal body composition in patients with rheumatoid arthritis (RA). Methods Combining data from three RA cohorts, whole-body dual-energy absorptiometry measures of appendicular lean mass and fat mass indices were converted to age, sex, and race-specific Z-Scores. Lean mass relative to fat mass was determined based on prior methods. Independent associations between body composition profiles and circulating levels of adiponectin, leptin, and fibroblast growth factor(FGF)-21 were assessed using linear and logistic regression models adjusting for demographics and study cohort. We also determined the improvement in the area-under-the-curve (AUC) for prediction of low lean mass when adipokines were added to predictive models that included clinical factors such as demographics, study, and body mass index (BMI). Results Among 419 participants, older age was associated with higher levels of all adipokines while higher C-reactive protein was associated with lower adiponectin levels and higher FGF-21 levels. Greater fat mass was strongly associated with lower adiponectin levels and higher leptin and FGF-21 levels. Higher levels of adiponectin, leptin, and FGF-21 were independently associated with low lean mass. The addition of adiponectin and leptin levels to regression models improved prediction of low lean mass when combined with demographics, study, and BMI (AUC 0.75 v. 0.66). Conclusions Adipokines are associated with both excess adiposity and low lean mass in patients with RA. Improvements in the prediction of body composition abnormalities suggest that laboratory screening could help identify patients with altered body composition who may be at greater risk of adverse outcomes.
Chapter
From a theoretical standpoint, skeletal muscle is a primary driver of the relationship between body composition, bone health, and clinical outcomes, as it is involved in mobility, strength, and balance. However, while muscles play a vital role in human health at all stages of life, it is the health factor that is rarely talked about. Throughout life, the tissue masses of bone and muscle are tightly correlated. During organogenesis, muscle and bone develop in close association from common mesodermal precursors to determine adult muscle and bone mass. In addition, changes in muscle and bone mass brought about by exercise or disuse are also closely coupled. With age, loss of muscle mass is associated with loss of bone mass. Despite these obvious examples suggesting coupling of bone and muscle mass, the precise mechanisms responsible for synchronizing bone and skeletal mass remain unclear. This chapter discusses the evolution of muscle health as a key factor of the broad musculoskeletal health, and its important role in health and healthy aging. It combines the basic, yet up to date, information about muscle health, the muscle bone interaction, together with discussions on the muscle health in aging and disease and approaches to management of muscle loss.
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The past few decades have shown a worrisome increase in the prevalence of obesity and its related illnesses. This increasing burden has a noteworthy impact on overall worldwide mortality and morbidity, with significant economic implications as well. The same trend is apparent regarding pediatric obesity. This is a particularly concerning aspect when considering the well-established link between cardiovascular disease and obesity, and the fact that childhood obesity frequently leads to adult obesity. Moreover, most obese adults have a history of excess weight starting in childhood. In addition, given the cumulative character of both time and severity of exposure to obesity as a risk factor for associated diseases, the repercussions of obesity prevalence and related morbidity could be exponential in time. The purpose of this review is to outline key aspects regarding the current knowledge on childhood and adolescent obesity as a cardiometabolic risk factor, as well as the most common etiological pathways involved in the development of weight excess and associated cardiovascular and metabolic diseases.
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Introduction: few studies have evaluated body composition (BC) through different techniques, and the degree of agreement between them in adults with cystic fibrosis (CF). Objectives: to describe BC using techniques to assess nutritional status and to test their concordance in CF. Methods: a cross-sectional study in CF patients in a clinically stable situation. Nutritional assessment was performed using skinfold measurement (SM) and densitometry (DXA). Fat-free mass index (FFMI) was also determined. The diagnosis of malnutrition was established if body mass index (BMI) < 18.5 kg/m2. Fat-free mass (FFM) malnutrition was diagnosed when FFMI was < 17 kg/m2 in males and < 15 kg/m2 in females (FFMI: fat-free mass in kg/height in m2). Results: forty-one patients were studied (twenty-two females, 53.7 %); median age was 29.8 (interquartile range, 20.9-33.7); BMI was 21.6 (19.8-23.0). Only four (9.8 %) patients had a BMI < 18.5. By DXA, FFM (kg) results were: median, 52.8 (47.8-56.9) with FFMI of 17.9 (16.7-19.3) in males and 36.7 (33.1-38.9) in females, FFMI of 14.7 (14.2-15.8). Twenty (48.6 %) patients presented FFM malnutrition, with 16.7 % of males and 59.1 % of females being affected. By SM, the FFMI was 18.7 (17.2-20.0) in males and 14.9 (14.2-15.8) in females; moreover, sixteen (39.1 %) patients presented malnutrition of FFM, with 20.8 % of males and 61.8 % of females being affected. For FFM (kg), a high concordance was obtained between SM and DXA (intraclass correlation coefficient of 0.950); likewise when they were compared by applying the ESPEN criteria for FFM malnutrition. However, when the techniques were compared to classify malnutrition according to FFMI, the kappa coefficient was only moderate (k = 0.440). The mean difference between FFM by DXA and SM was +1.44 ± 0.62 kg in favor of SM, with greater dispersion as FFM increased. Conclusions: the prevalence of FFM malnutrition is high in adult CF patients, despite a normal BMI, especially in females. Notwithstanding the good statistical agreement between SM and DXA, concordance was moderate. Therefore, DXA remains the technique of choice, and SM may be used when the former is not available.
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The analysis of human body composition plays a critical role in health management and disease prevention. However, current medical technologies to accurately assess body composition such as dual energy X-ray absorptiometry, computed tomography, and magnetic resonance imaging have the disadvantages of prohibitive cost or ionizing radiation. Recently, body shape based techniques using body scanners and depth cameras, have brought new opportunities for improving body composition estimation by intelligently analyzing body shape descriptors. In this paper, we present a multi-task deep neural network method utilizing a conditional generative adversarial network to predict the pixel level body composition using only 3D body surfaces. The proposed method can predict 2D subcutaneous and visceral fat maps in a single network with a high accuracy. We further introduce an interpreted patch discriminator which optimizes the textural accuracy of the 2D fat maps. The validity and effectiveness of our new method are demonstrated experimentally on TCIA and LiTS datasets. Our proposed approach outperforms competitive methods by at least 41.3% for the whole body fat percentage, 33.1% for the subcutaneous and visceral fat percentage, and 4.1% for the regional fat predictions.
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Purpose: We investigate the feasibility of slot-scan dual-energy (DE) bone densitometry on motorized radiographic equipment. This approach will enable fast quantitative measurements of areal bone mineral density (aBMD) for opportunistic evaluation of osteoporosis. Methods: We investigated DE slot-scan protocols to obtain aBMD measurements at the lumbar spine (L-spine) and hip using a motorized x-ray platform capable of synchronized translation of the x-ray source and flat-panel detector (FPD). The slot dimension was 5 × 20 cm2 . The DE slot views were processed as follows: 1) convolution kernel-based scatter correction, 2) unfiltered backprojection to tile the slots into long-length radiographs, and 3) projection-domain DE decomposition, consisting of an initial adipose-water decomposition in a bone-free region followed by water-CaHA decomposition with adjustment for adipose content. The accuracy and reproducibility of slot-scan aBMD measurements was investigated using a high-fidelity simulator of a robotic x-ray system (Siemens Multitom Rax) in a total of 48 body phantom realizations: 4 average bone density settings (cortical bone mass fraction: 10-40%), 4 body sizes (waist circumference, WC = 70-106 cm), and 3 lateral shifts of the body within the slot field of view (FOV) (centered and ±1 cm off-center). Experimental validations included: (i) x-ray test-bench feasibility study of adipose-water decomposition and (ii) initial demonstration of slot-scan DE bone densitometry on the robotic x-ray system using the European Spine Phantom (ESP) with added attenuation (PMMA slabs) ranging 2 to 6 cm thick. Results: For the L-spine, the mean aBMD error across all WC settings ranged from 0.08 g/cm2 for phantoms with average cortical bone fraction wcortical = 10% to ∼0.01 g/cm2 for phantoms with wcortical = 40%. The L-spine aBMD measurements were fairly robust to changes in body size and positioning, e.g., coefficient of variation (CV) for L1 with wcortical = 30% was ∼0.034 for various WC and ∼0.02 for an obese patient (WC = 106 cm) changing lateral shift. For the hip, the mean aBMD error across all phantom configurations was about 0.07 g/cm2 for a centered patient. The reproducibility of hip aBMD was slightly worse than in the L-spine (e.g., in the femoral neck, the CV with respect to changing WC was ∼0.13 for phantom realizations with wcortical = 30%) due to more challenging scatter estimation in the presence of an air-tissue interface within the slot FOV. The aBMD of the hip was therefore sensitive to lateral positioning of the patient, especially for obese patients: e.g., the CV with respect to patient lateral shift for femoral neck with WC = 106 cm and wcortical = 30% was 0.14. Empirical evaluations confirmed substantial reduction in aBMD errors with the proposed adipose estimation procedure and demonstrated robust aBMD measurements on the robotic x-ray system, with aBMD errors of ∼0.1 g/cm2 across all three simulated ESP vertebrae and all added PMMA attenuator settings. Conclusions: We demonstrated that accurate aBMD measurements can be obtained on a motorized FPD-based x-ray system using DE slot-scans with kernel-based scatter correction, backprojection-based slot view tiling, and DE decomposition with adipose correction. This article is protected by copyright. All rights reserved.
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Objective We determined the prevalence of sarcopenic obesity in patients with rheumatoid arthritis (RA) using multiple methods and assessed associations with physical functioning. Methods This study evaluated data from three RA cohorts. Whole-body dual-energy absorptiometry (DXA) measures of appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI) were converted to age, sex, and race-specific Z-Scores and categorized using a recently validated method and compared it to a widely-used existing method. The prevalence of body composition abnormalities in RA was compared with two reference populations. In the RA cohorts, associations between body composition and change in the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB) in follow-up were assessed using linear and logistic regression, adjusting for age, sex, race, and study. Results The prevalence of low lean mass and sarcopenic obesity were higher in patients with RA (14.2; 12.6%, respectively) compared with the reference population cohorts (7–10%; 4–4.5%, respectively, all p< 0.05). There was only moderate agreement among methods of sarcopenic obesity categorization (Kappa 0.45). The recently validated method categorized fewer subjects as obese, and many of these were categorized as low lean mass only. Low lean mass, obesity, and sarcopenic obesity were each associated with higher HAQ and lower SPPB at baseline and numerically greater worsening. Conclusion RA patients had higher rates of low lean mass and sarcopenic obesity than the general population. The recently validated methods characterized body composition changes differently from traditional methods and were more strongly associated with physical function.
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Background: Bilateral oophorectomy during a non-malignant hysterectomy is frequently performed for ovarian cancer prevention in premenopausal women. Oophorectomy before menopause leads to an abrupt decline in ovarian hormones that could adversely impact body composition. We examined the relationship between oophorectomy and whole-body composition. Methods: Our study population included cancer-free women 35-70 years old from the 1999-2006 National Health and Nutrition Examination Survey, a representative sample of the U.S. Population: A total of 4,209 women with dual-energy x-ray absorptiometry scans were identified, including 445 with hysterectomy, 552 with hysterectomy and oophorectomy, and 3,212 with no surgery. Linear regression was used to estimate the difference in total and regional (trunk, arms, legs) fat and lean body mass by surgery status. Results: In multivariable models, hysterectomy with and without oophorectomy was associated with higher total fat mass (mean percent difference (β); βoophorectomy: 1.61%, 95% CI: 1.00, 2.28%; βhysterectomy: 0.88%, 95% CI: 0.12, 1.58) and lower total lean mass (βoophorectomy: -1.48%, 95% CI: -2.67, -1.15; βhysterectomy: -0.87%, 95% CI: -1.50, -0.24) compared to no surgery. Results were stronger in women with a normal BMI and those <45 years at surgery. All body regions were significantly affected for women with oophorectomy, while only the trunk was affected for women with hysterectomy alone. Conclusions: Hysterectomy with oophorectomy, particularly in young women, may be associated with systemic changes in fat and lean body mass irrespective of BMI. Impact: Our results support prospective evaluation of body composition in women undergoing hysterectomy with oophorectomy at a young age.
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Background: Most methods available to clinicians for estimating body-composition changes have been validated against estimates from densitometry, based on a 2-component (fat mass and fat-free mass) model. Objective: Estimates of changes in percentage body fat (%BF) from dual-energy X-ray absorptiometry (DXA), skinfold thicknesses (SFTs), bioelectrical impedance analysis (BIA), and body mass index (BMI; in kg/m²) were compared with estimates from a 4-component (fat, water, mineral, and protein) model (%BFd,w,m), a more accurate method. Design: Determinations of body density from hydrostatic weighing, body water from deuterium dilution, bone mineral and %BF from whole-body DXA, resistance from BIA, and anthropometric measures were made in 27 obese women (BMI: 31.1 ± 4.9) assigned to 1 of 3 groups: control (C; n = 9), diet only (DO; n = 9), or diet plus aerobic exercise (DE; n = 9). Results: After the 16-wk intervention, changes in body mass (BM) averaged 0.5 ± 2.0, −7.2 ± 7.4, and −4.0 ± 3.3 kg and changes in %BFd,w,m averaged 2.1 ± 1.0%, −1.2 ± 1.4%, and −2.4 ± 1.6% in the C, DO, and DE groups, respectively. Compared with changes in %BFd,w,m, the errors (SD of bias) for estimates of changes in %BF by DXA, BIA, SFTs, and BMI were similar (range: ±2.0–2.4% of BM). BIA, SFTs, and BMI provided unbiased estimates of decreases in %BFd,w,m, but DXA overestimated decreases in %BF in the DO and DE groups. Conclusions: DXA, BIA, SFTs, and BMI are comparably accurate for evaluating body-composition changes induced by diet and exercise interventions; however, small changes in %BF may not be accurately detected by these clinical methods.
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The objective of this study was to cross-calibrate measurements of body composition by dual-energy X-ray absorptiometry (DXA) with chemical analysis of carcasses of pigs in the pediatric range of body weight. Eighteen pigs (25.5 +/- 7.0 kg; 9.9-32.8% body fat) were scanned in duplicate by using DXA with a Lunar DPX-L densitometer in the pediatric medium and adult fast-detail scan modes. Pigs were then killed and their carcasses analyzed completely. Carcass lean and fat contents were highly correlated with DXA measurement in both scan modes (Pearson r values > 0.98). For lean mass, the relation between carcass content and DXA measures was not significantly different from the line of identity in the adult mode, but was in the pediatric mode. For fat mass, the relations between carcass content and DXA measures were significantly different from the line of identity in both the adult and pediatric modes. In duplicate scans, the reliability of DXA measures of lean mass and fat mass was excellent in both scan modes. Because neither the adult nor the pediatric scan mode provided accurate measures of fat and lean mass, we derived specific correction factors to improve the measurement of total fat and lean compartments, thereby calibrating the Lunar DPX-L to the laboratory standard of carcass analysis in pigs.
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The objective was to compare measures from dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and anthropometry with a reference four-compartment model to estimate fat mass (FM) and fat-free mass (FFM) changes in overweight and obese women after a weight-loss programme. Forty-eight women (age 39.8 ± 5.8 years; weight 79·2 ± 11·8 kg; BMI 30·7 ± 3·6 kg/m2) were studied in an out-patient weight-loss programme, before and after the 16-month intervention. Women attended weekly meetings for the first 4 months, followed by monthly meetings from 4 to 12 months. Body composition variables were measured by the following techniques: DXA, anthropometry (waist circumference-based model; Antrform), BIA using Tanita (TBF-310) and Omron (BF300) and a reference four-compartment model. Body weight decreased significantly ( − 3·3 (sd 3·1) kg) across the intervention. At baseline and after the intervention, FM, percentage FM and FFM assessed by Antrform, Tanita, BF300 and DXA differed significantly from the reference method (P ≤ 0·001), with the exception of FFM assessed by Tanita (baseline P = 0·071 and after P = 0·007). DXA significantly overestimated the change in FM and percentage FM across weight loss ( − 4·5 v. − 3·3 kg; P < 0·001 and − 3·7 v. − 2·0 %; P < 0·001, respectively), while Antrform underestimated FM and percentage FM ( − 2·8 v. − 3·3 kg; P = 0·043 and − 1·1 v. − 2·0 %; P = 0·013) compared with the four-compartment model. Tanita and BF300 did not differ (P>0·05) from the reference model in any body composition variables. We conclude that these methods are widely used in clinical settings, but should not be applied interchangeably to detect changes in body composition. Furthermore, the several clinical methods were not accurate enough for tracking body composition changes in overweight and obese premenopausal women after a weight-loss programme.
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The metabolic syndrome refers to the clustering of cardiovascular risk factors that include diabetes, obesity, dyslipidaemia and hypertension. Due to various definitions and unexplained pathophysiology it is still a source of medical controversy. Insulin resistance and visceral obesity have been recognized as the most important pathogenic factors. Insulin resistance could be defined as the inability of insulin to produce its numerous actions, in spite of the unimpaired secretion from the beta cells. Metabolic abnormalities result from the interaction between the effects of insulin resistance located primarily in the muscle and adipose tissue and the adverse impact of the compensatory hyperinsulinaemia on tissues that remain normally insulin-sensitive. The clinical heterogeneity of the syndrome can be explained by its significant impact on glucose, fat and protein metabolism, cellular growth and differentiation, and endothelial function. Visceral fat represents a metabolically active organ, strongly related to insulin sensitivity. Moderating the secretion of adipocytokines like leptin, adiponectin, plasminogen activator inhibitor 1 (PAI-1), tumor necrosis factor alfa (TNF-alfa), interleukin-6 (IL-6) and resistin, it is associated with the processes of inflammation, endothelial dysfunction, hypertension and atherogenesis. In 2005, the International Diabetes Federation (IDF) has proposed a new definition, based on clinical criteria and designed for global application in clinical practice. Visceral obesity measured by waist circumference is an essential requirement for diagnosis; other variables include increased triglyceride and decreased HDL levels, hypertension and glucose impairment. Whatever the uncertainties of definition and etiology, metabolic syndrome represents a useful and simple clinical concept which allows earlier detection of type 2 diabetes and cardiovascular disease.
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To examine the inter-relationships of body composition variables derived from simple anthropometry [BMI and skinfolds (SFs)], bioelectrical impedance analysis (BIA), and dual energy x-ray (DXA) in young children. Seventy-five children (41 girls, 34 boys) 3 to 8 years of age were assessed for body composition by the following methods: BMI, SF thickness, BIA, and DXA. DXA served as the criterion measure. Predicted percentage body fat (%BF), fat-free mass (FFM; kilograms), and fat mass (FM; kilograms) were derived from SF equations [Slaughter (SL)1 and SL2, Deurenberg (D) and Dezenberg] and BIA. Indices of truncal fatness were also determined from anthropometry. Repeated measures ANOVA showed significant differences among the methods for %BF, FFM, and FM. All methods, except the D equation (p = 0.08), significantly underestimated measured %BF (p < 0.05). In general, correlations between the BMI and estimated %BF were moderate (r = 0.61 to 0.75). Estimated %BF from the SL2 also showed a high correlation with DXA %BF (r = 0.82). In contrast, estimated %BF derived from SFs showed a low correlation with estimated %BF derived from BIA (r = 0.38); likewise, the correlation between DXA %BF and BIA %BF was low (r = 0.30). Correlations among indicators of truncal fatness ranged from 0.43 to 0.98. The results suggest that BIA has limited utility in estimating body composition, whereas BMI and SFs seem to be more useful in estimating body composition during the adiposity rebound. However, all methods significantly underestimated body fatness as determined by DXA, and, overall, the various methods and prediction equations are not interchangeable.
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In vivo precision for body composition measurements using dual energy X-ray absorptiometry (DXA; GE Lunar iDXA, GE Healthcare, Bucks, UK) was evaluated in 52 men and women, aged 34.8 (s.d. 8.4; range 20.1-50.5) years, body mass index (25.8 kg/m(2); range 16.7-42.7 kg/m(2)). Two consecutive total body scans (with re-positioning) were conducted. Precision was excellent for all measurements, particularly for total body bone mineral content and lean tissue mass (root mean square 0.015 and 0.244 kg; coefficients of variation (CV) 0.6 and 0.5%, respectively). Precision error was CV 0.82% for total fat mass and 0.86% for percentage fat. Precision was better for gynoid (root mean square 0.397 kg; CV 0.96%) than for android fat distribution (root mean square 0.780 kg, CV 2.32%). There was good agreement between consecutive measurements for all measurements (slope (s.e.) 0.993-1.002; all R(2) = 0.99). The Lunar iDXA provided excellent precision for total body composition measurements. Research into the effect of body size on the precision of DXA body fat distribution measurements is required.
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Dual-energy x-ray absorptiometry (DXA) provides an affordable and practical assessment of multiple whole body and regional body composition. However, little information is available on the assessment of changes in body composition in top-level athletes using DXA. The present study aimed to assess the accuracy of DXA in tracking body composition changes (relative fat mass [%FM], absolute fat mass [FM], and fat-free mass [FFM]) of elite male judo athletes from a period of weight stability to prior to a competition, compared to a four compartment model (4C model), as the criterion method. A total of 27 elite male judo athletes (age, 22.2 +/- 2.8 yrs) athletes were evaluated. Measures of body volume by air displacement plethysmography, bone mineral content assessed by DXA, and total-body water assessed by deuterium dilution were used in a 4C model. Statistical analyses included examination of the coefficient of determinant (r2), standard error of estimation (SEE), slope, intercept, and agreement between models. At a group level analysis, changes in %FM, FM, and FFM estimates by DXA were not significantly different from those by the 4C model. Though the regression between DXA and the 4C model did not differ from the line of identity DXA %FM, FM, and FFM changes only explained 29%, 36%, and 38% of the 4C reference values, respectively. Individual results showed that the 95% limits of agreement were -3.7 to 5.3 for %FM, -2.6 to 3.7 for FM, and -3.7 to 2.7 for FFM. The relation between the difference and the mean of the methods indicated a significant trend for %FM and FM changes with DXA overestimating at the lower ends and underestimating at the upper ends of FM changes. Our data indicate that both at group and individual levels DXA did not present an expected accuracy in tracking changes in adiposity in elite male judo athletes.
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Accurate methods for assessing body composition in subjects with obesity and anorexia nervosa (AN) are important for determination of metabolic and cardiovascular risk factors and to monitor therapeutic interventions. The purpose of our study was to assess the accuracy of dual-energy X-ray absorptiometry (DXA) for measuring abdominal and thigh fat, and thigh muscle mass in premenopausal women with obesity, AN, and normal weight compared to computed tomography (CT). In addition, we wanted to assess the impact of hydration on DXA-derived measures of body composition by using bioelectrical impedance analysis (BIA). We studied a total of 91 premenopausal women (34 obese, 39 with AN, and 18 lean controls). Our results demonstrate strong correlations between DXA- and CT-derived body composition measurements in AN, obese, and lean controls (r = 0.77-0.95, P < 0.0001). After controlling for total body water (TBW), the correlation coefficients were comparable. DXA trunk fat correlated with CT visceral fat (r = 0.51-0.70, P < 0.0001). DXA underestimated trunk and thigh fat and overestimated thigh muscle mass and this error increased with increasing weight. Our study showed that DXA is a useful method for assessing body composition in premenopausal women within the phenotypic spectrum ranging from obesity to AN. However, it is important to recognize that DXA may not accurately assess body composition in markedly obese women. The level of hydration does not significantly affect most DXA body composition measurements, with the exceptions of thigh fat.
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Body mass index (BMI), waist circumference (WC), and the waist-stature ratio (WSR) are considered to be possible proxies for adiposity. The objective was to investigate the relations between BMI, WC, WSR, and percentage body fat (measured by dual-energy X-ray absorptiometry) in adults in a large nationally representative US population sample from the National Health and Nutrition Examination Survey (NHANES). BMI, WC, and WSR were compared with percentage body fat in a sample of 12,901 adults. WC, WSR, and BMI were significantly more correlated with each other than with percentage body fat (P < 0.0001 for all sex-age groups). Percentage body fat tended to be significantly more correlated with WC than with BMI in men but significantly more correlated with BMI than with WC in women (P < 0.0001 except in the oldest age group). WSR tended to be slightly more correlated with percentage body fat than was WC. Percentile values of BMI, WC, and WSR are shown that correspond to percentiles of percentage body fat increments of 5 percentage points. More than 90% of the sample could be categorized to within one category of percentage body fat by each measure. BMI, WC, and WSR perform similarly as indicators of body fatness and are more closely related to each other than with percentage body fat. These variables may be an inaccurate measure of percentage body fat for an individual, but they correspond fairly well overall with percentage body fat within sex-age groups and distinguish categories of percentage body fat.
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Multicompartment models are of growing importance in the study of body composition in humans. This study compares two improved four-compartment (water, protein, mineral, and fat) models that differ in expense, technological complexity, and radiation exposure. Primary data (from 31 subjects) for the first model were derived by dual-photon absorptiometry, 3H2O dilution, and hydrodensitometry and for the second model by delayed and prompt gamma neutron-activation analysis and 3H2O dilution. Estimates of fat, protein, and mineral from the first model were highly correlated with those from the second model (r = 0.98, 0.72, and 0.94, respectively; all p less than 0.001). The proportions of body weight represented by water, protein, mineral, and fat for the simpler first model (0.532, 0.155, 0.048, and 0.265) were similar to compartment fractions provided by the more complex and costly second model (0.532, 0.143, 0.046, and 0.279). Multicompartment body composition models can thus be developed from increasingly available techniques that compare favorably with similar results derived from limited-access instrumentation.
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Precision and validity of dual-energy x-ray absorptiometry (DXA) for analysis of whole-body composition in infants were assessed by 1) scanning piglets in triplicate to calculate CVs, and 2) comparing DXA estimates with chemical analysis of whole carcass. The mean CVs for all DXA measures in small piglets and large piglets were < 2.5%, except for fat mass, which were 6.3% and 3.5%, respectively. In large piglets DXA provided reasonable estimates of chemical analysis for bone mineral content (BMC), lean body mass, and fat mass, but only for lean body mass in small piglets. DXA overestimated fat by twofold and underestimated BMC by a third in small piglets. Scans of prematurely born infants (n = 17) at term and at 3, 6, and 12 mo corrected age demonstrated that changes in BMC, lean body mass, and fat mass can be quantitated by DXA. However, further refinement of DXA technology is necessary before reliable measures of BMC and fat mass in small infants are attainable.
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The accuracy of body-composition measurements in vivo by dual-energy x-ray absorptiometry (DEXA) was assessed in seven pigs (weight: 35-95 kg) by measurement by DEXA in vivo and chemical analysis after postmortem homogenization. The regression lines between these measurements were not significantly different from the line of identity (P > 0.05), the r values were > 0.97, and the corresponding SEEs were 2.9%, 1.9 kg, and 2.7 kg for percent fat, fat tissue mass, and lean body mass, respectively. Changes in fat and lean tissue mass (simulated by placing 8.8 kg porcine lard on the trunk of six women) were accurately measured by DEXA. The measured total-body bone mineral (TBBM) was significantly affected by the lard (P < 0.05). In conclusion, DEXA is an accurate method for measurement of soft-tissue body composition. TBBM measurements in longitudinal studies may, however, be difficult to interpret if considerable change in soft-tissue composition has occurred.
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The reproducibility, accuracy, and precision of dual-energy X-ray absorptiometry (DXA) was assessed by scanning 13 piglets (1471-5507 g) in triplicate. In four piglets, fat content was increased with porcine lard around the abdomen; additional measurements were performed on these animals. Reproducibility in DXA measurements from the animals without added fat was 0.09% for body weight, 1.95% for bone mineral content (BMC), and 5.35% for fat content. DXA estimates of body weight, BMC, and fat content were significantly correlated with scale body weight, ash weight, chemical calcium, and chemical fat. Body weight was measured accurately but fat content was overestimated by DXA. Mean BMC estimated by DXA represented 48% of ash weight and 215% of calcium content. The precision of DXA was 0.23% for body weight, 10.99% for ash weight, and 4.44% for calcium content. The precision of DXA for fat content was poor. However, for measurements performed in piglets with > 250 g fat, the precision was 8.85%. Thirty appropriate-forgestational-age term human neonates (birth weight: 3188 +/- 217 g) were scanned once during the first week of life. BMC and fat content were 54 +/- 6 and 470 +/- 92 g, respectively, which corresponded to 26.4 +/- 2.6 g calcium and 427 +/- 82 g fat. These were close to the reference values previously determined by chemical analysis. This study suggests that DXA is accurate and reliable for measurement of calcium and fat contents in human neonates. Further refinements would be beneficial for determining fat content in preterm human infants.
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The objective of this study was to cross-calibrate measurements of body composition by dual-energy X-ray absorptiometry (DXA) with chemical analysis of carcasses of pigs in the pediatric range of body weight. Eighteen pigs (25.5 +/- 7.0 kg; 9.9-32.8% body fat) were scanned in duplicate by using DXA with a Lunar DPX-L densitometer in the pediatric medium and adult fast-detail scan modes. Pigs were then killed and their carcasses analyzed completely. Carcass lean and fat contents were highly correlated with DXA measurement in both scan modes (Pearson r values > 0.98). For lean mass, the relation between carcass content and DXA measures was not significantly different from the line of identity in the adult mode, but was in the pediatric mode. For fat mass, the relations between carcass content and DXA measures were significantly different from the line of identity in both the adult and pediatric modes. In duplicate scans, the reliability of DXA measures of lean mass and fat mass was excellent in both scan modes. Because neither the adult nor the pediatric scan mode provided accurate measures of fat and lean mass, we derived specific correction factors to improve the measurement of total fat and lean compartments, thereby calibrating the Lunar DPX-L to the laboratory standard of carcass analysis in pigs.
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The purpose of this study was to compare body-composition and whole-body, lumbar spine (LS), femoral neck (FN), trochanter, and Ward's triangle (WT) bone mineral measurements by using the Hologic QDR 1000W (DXAH) and the Lunar DPX-L (DXAL) dual-energy X-ray absorptiometry instruments. In addition, the ability of conversion equations to predict DXAH data from DXAL data were tested. Thirteen healthy young adult males (aged 22.2 +/- 3.6 y, 177.4 +/- 5.3 cm in height, and 72.7 +/- 9.6 kg in weight) were scanned on the same day by using DXAH and DXAL. Whereas measured body mass was not different (P > 0.05) between machines, whole-body fat mass [DXAH-DXAL (DXAdiff) = 1152 +/- 1395 g], percentage fat (DXAdiff = 1.5 +/- 1.7% of body mass), bone mineral density (BMD; DXAdiff = 0.016 +/- 0.023 g/cm2), and bone mineral content (BMC; DXAdiff = 316 +/- 50 g) were lower and whole-body fat-free soft tissue (FFST; DXAdiff = 1781 +/- 1859 g) was higher with DXAH than with DXAL. Lower fat mass (DXAdiff = 2145 +/- 855 g) and BMC (DXAdiff = 216 +/- 36 g) and higher FFST (DXAdiff = 1966 +/- 943 g) in the trunk were primarily responsible for the whole-body differences. Lower BMD and BMC values were found for LS (DXAdiff = 0.145 +/- 0.038 g/cm2 and 3 +/- 2 g, respectively), trochanter (DXAdiff = 0.100 +/- 0.044 g/cm2 and 1.7 +/- 1.0 g), and WT (DXAdiff = 0.195 +/- 0.061 g/cm2 and 1.93 +/- 0.51 g) with DXAH compared with DXAL. DXAH BMD of FN was also lower (DXAdiff = 0.141 +/- 0.032 g/cm2) than with DXAL. Only DXAH whole-body BMC and LS BMD were accurately predicted from DXAL with conversion equations. Predicted DXAH FN BMD was significantly lower than the actual DXAH value (P < or = 0.05), whereas the discrepancy between DXAH and DXAL actually increased for whole-body percentage fat and BMD (DXAdiff = 6.6 +/- 1.3% body mass and 0.020 +/- 0.025 g/cm2). In conclusion, lower whole-body fat mass, percentage fat, and BMC, and higher whole-body FFST with DXAH were due primarily to measurement differences in the trunk. Whereas conversion equations accurately predicted DXAH whole-body BMC and LS BMD from DXAL measurements in young adult males, they did not accurately predict DXAH, percentage fat, and BMD of the whole body and FN BMD.
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Although dual-energy X-ray absorptiometry (DXA) is widely used in clinical research as a means of quantifying body composition, there remains at present little published information that reviews the method's underlying physical basis. Because a clear understanding of DXA physical concepts is integral to appropriate use and interpretation, we present here a three-section review that includes both relevant in vitro and in vivo experimental demonstrations. In the first section we describe the main physical principles on which DXA is based. The section that follows presents a step-by-step analysis of the DXA two-component soft tissue model. In the final section we demonstrate how knowledge of physical concepts can lead to resolution of important methodological concerns, such as the influence of hydration changes on DXA fat estimates. A thorough understanding of DXA physical concepts provides a basis for appropriate interpretation of measurement results and stimulates many new and important research questions.
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Bone mineral content is reliably measured by dual energy X-ray absorptiometry (DXA), if manufacturers' recommendations and quality control (QC) procedures are followed. Several phantoms (Hologic anthropomorphic spine phantom, the Groupe de Recherche et d'Informations sur les Osteoporoses (GRIO) test objects and the European semi-anthropomorphic phantoms) were used to evaluate reproducibility, linearity, accuracy and spatial resolution of two DXA devices in vitro. These parameters were also evaluated in vivo from measurements performed on 120 volunteer patients. It was found that when one device (a single beam monodetector QDR 1000) is replaced by another (a fan beam multidetector QDR 4500/A), the novel combination of procedures described here, ensures that the accuracy of DXA study results is maintained when both devices are used in succession for the same patient. To study the possible responses in clinical situations, the influence of bone environment (soft and adipose tissues) was also evaluated. In both systems, similar performances (in vitro coefficients of variation of 0.5%) were established. At extreme bone density values, slight differences in linearity were found, as well as differences in accuracy and spatial resolution. Lumbar spine and femoral neck measurements were performed with both systems in 120 volunteers, both measurements being made on the same day. The corresponding bone mineral density (BMD) values were highly correlated (r2 = 0.985 for lumbar spine and 0.948 for the femoral neck), and the mean BMD differences were 0.68% and 0.37% for each anatomical site, respectively. Although small, these differences add to the precision error of the method, which is near 1%. A calibration curve has to be obtained in order that both devices can be equally used in regular clinical study. We concluded that when a DXA system is replaced by a new one, appropriate QC procedures must be strictly observed.
Article
International Commission on Radiological Protection (ICRP) Publication 103 provided a detailed explanation of the purpose and use of effective dose and equivalent dose to individual organs and tissues. Effective dose has proven to be a valuable and robust quantity for use in the implementation of protection principles. However, questions have arisen regarding practical applications, and a Task Group has been set up to consider issues of concern. This paper focuses on two key proposals developed by the Task Group that are under consideration by ICRP: (1) confusion will be avoided if equivalent dose is no longer used as a protection quantity, but regarded as an intermediate step in the calculation of effective dose. It would be more appropriate for limits for the avoidance of deterministic effects to the hands and feet, lens of the eye, and skin, to be set in terms of the quantity, absorbed dose (Gy) rather than equivalent dose (Sv). (2) Effective dose is in widespread use in medical practice as a measure of risk, thereby going beyond its intended purpose. While doses incurred at low levels of exposure may be measured or assessed with reasonable reliability, health effects have not been demonstrated reliably at such levels but are inferred. However, bearing in mind the uncertainties associated with risk projection to low doses or low dose rates, it may be considered reasonable to use effective dose as a rough indicator of possible risk, with the additional consideration of variation in risk with age, sex and population group.
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IntroductionGeneral Limitations of BTMS and their Analytical and Preanalytical VariabilitySelected Determinants of the Preanalytical VariabilityChanges in BTM Levels after MenopauseAssociation Between BTM Levels and Rate of Bone LossAssociation Between Bone Turnover Rate and Risk of FractureBiochemical BTMs and Anti-Osteoporotic TreatmentMetabolic Effect of Anti-Osteoporotic TreatmentDose-Finding StudiesDecrease in BTM Levels and Antifracture Efficacy of Antiresorptive TreatmentBTM Levels and Antifracture Efficacy of Bone Formation-Stimulating TreatmentChanges in Bone Turnover after Discontinuation of Anti-Osteoporotic TreatmentCombination Therapy and BTMsAssociation Between BTM Levels and Adherence with Antiresorptive TreatmentBTMs in MenEffect of Anti-Osteoporotic Treatment on BTM in MENConclusions