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Background: There is limited research on body composition in persons with haemophilia (PwH). The literature describes an increased body fat distribution and decreased lean mass in PwH compared to healthy controls using bioimpedance analysis. Using dual x-ray absorptiometry (DXA), which is known to be the most accurate method, this investigation aims to postulate reference data for body composition parameters within haemophilia severity phenotypes and age groups., Methods: Persons underwent whole body DXA screening using Horizon. Body fat percentage, estimated visceral adipose tissue (VAT), appendicular fat and lean mass, and lean and fat mass in relation to body height were assessed. Haemophilia severity and five age groups were distinguished., Results: Two hundred and one persons with mild (n = 44), moderate (n = 41), or severe (n = 116) haemophilia A/B (median age 40 [28-55; 1.IQ-3.IQ] years) were analysed. The median body fat percentage was 28.7% [25.5%-33.9%] and median estimated VAT was 657 g [403-954 g] with no significant difference between severity phenotypes (p = .474; p = .781). Persons with severe haemophilia had less lean mass compared to moderate and mild haemophilia (p = .013; p = .034). Total and appendicular fat is increased in older PwH (aged ≥40 years) compared to younger PwH (aged ≤29 years; p < .05). Lean mass did not differ between age groups., Conclusion: This study provides valuable reference data for body composition parameters in PwH. Persons with severe haemophilia show significantly less lean mass compared to persons with moderate or mild haemophilia. Body fat percentage and VAT did not differ between severity phenotypes, but increased with age., (© 2024 The Author(s). Haemophilia published by John Wiley & Sons Ltd.)

Preterm infants have increased body adiposity at term-equivalent age and risk of adverse metabolic outcomes. The aim of the study was to define how nutrient intake may impact body composition (BC) of very low-birth weight infants fed with early progressive enteral feeding and standard fortification. Eighty-six infants with <1500 g birth weight were included in the BC study and stratified into extremely preterm (EP) and very preterm (VP) groups. Nutrient intake was calculated during the first 28 days and BC assessed by dual X-ray absorptiometry at discharge and by skinfold thickness at 12 months of corrected age (CA). Total nutrient intake did not differ between the groups. EP infants had a higher fat mass percentage at discharge than VP infants (24.8% vs. 19.4%, p < 0.001); lean mass did not differ. None of the nutrients had any impact on BC of EP infants. Protein intake did not result in a higher lean mass in either group; fat intake was a significant predictor of increased fat mass percentage in VP infants at discharge ( p = 0.007) and body adiposity at 12 months of CA ( p = 0.021). Nutritional needs may depend on gestational age and routine fortification should be used with caution in more mature infants.

Several techniques exist to measure fat-free mass (FFM). Accordingly, this study is based on data from our recent trial comparing the sensitivity of the main field methods available with that of dual-energy X-ray absorptiometry (DXA) as reference and analyzing the cross-sectional accuracy of these field methods in recreationally resistance-trained males. We hypothesized that the use of these techniques would lead to varying estimates of FFM compared with DXA. Participants (N = 23; 21.4 ± 3.3 years) completed a 10-week resistance training plus diet intervention designed to optimize hypertrophy. FFM was determined by bioelectrical impedance analysis (BIA), 23 anthropometric equations, and DXA. After the intervention, FFM increased significantly according to BIA and most anthropometric estimates, but this increase was not detected by 2 anthropometric equations or by DXA. Only 1 of these 2 equations showed significant correlation with DXA and no standardized or significant differences to this reference method, although it did display significant heteroscedasticity. In our cross-sectional analysis, only 1 anthropometric equation gave rise to good accuracy as confirmed by DXA. Our findings indicate that the use of different techniques to assess FFM gains in response to a hypertrophic intervention yields different results. BIA with general embedded equations should not be used to monitor a young male adult's body composition. To monitor FFM over time, we would recommend the Dunne et al. equation (2) as the most sensitive field method, and to assess FFM cross-sectionally, equation (1) of these authors is the most accurate field method., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Children spend increasing amounts of time on recreational screen media, which may lead to an obesogenic environment., Objectives: We investigated the association of trajectories of screen time across ages 3, 5 and 7 years with body composition at age 7 in the Odense Child Cohort., Methods: Data were collected in the Municipality of Odense, Denmark, between 2010 and 2019. Group-based trajectory modelling was applied to group participants into four trajectories of prospective parent-reported screen time. Body composition was assessed using dual-energy x-ray absorptiometry with calculated fat-mass index (FMI) as the primary outcome. Primary models were linear multivariable regression models adjusted for participants' sex, age, birthweight, maternal origin, maternal education, maternal body-mass-index, and maternal age. Further models were adjusted for additional possible confounders. Selection bias was addressed by inverse probability weighting., Results: In total, 803 children (48.2% female) were included in the primary analysis. Participants with screen time at all time points were assigned to four trajectory groups [constant low screen time (12.7%), low increase (36.3%), high increase between ages 3 and 5 (33.5%) and high increase in screen time (17.5%)]. Sample characteristics differed across missing data status and trajectories. Mean FMI (kg/m 2 ) and standard deviation (SD) were 3.7 (SD 1.3) and 3.9 (SD 1.6) for the constant low versus high screen time, respectively. No differences in FMI were found between screen time trajectory groups at age 7 (adjusted mean difference 0.1 kg/m 2 , 95% confidence interval -0.3, 0.5 for constant low versus high screen time). No consistent associations between screen time groups and secondary body composition outcomes were found., Conclusions: Results from this study do not suggest that recreational screen time from age 3 to 7 years is associated with adiposity or other measures of body composition., (© 2023 The Authors. Paediatric and Perinatal Epidemiology published by John Wiley & Sons Ltd.)

Background: Many predictors of morbidity caused by metabolic disease are associated with body shape. 3D optical (3DO) scanning captures body shape and has been shown to accurately and precisely predict body composition variables associated with mortality risk. 3DO is safer, less expensive, and more accessible than criterion body composition assessment methods such as dual-energy X-ray absorptiometry (DXA). However, 3DO scanning has not been standardized across manufacturers for pose, mesh resolution, and post processing methods., Purpose: We introduce a scanner-agnostic algorithm that automatically fits a topologically consistent human mesh to 3DO scanned point clouds and predicts clinically important body metrics using a standardized body shape model. Our models transform raw scans captured by any 3DO scanner into fixed topology meshes with anatomical consistency, standardizing the outputs of 3DO scans across manufacturers and allowing for the use of common prediction models across scanning devices., Methods: A fixed-topology body mesh template was automatically registered to 848 training scans from three different 3DO systems. Participants were between 18 and 89 years old with body mass index ranging from 14 to 52 kg/m 2 . Scans were registered by first performing a coarse nearest neighbor alignment between the template and the input scan with an anatomically constrained principal component analysis (PCA) domain deformation using a device and gender specific bootstrap basis trained on 70 seed scans each. The template mesh was then optimized to fit the target with a smooth per-vertex surface-to-surface deformation. A combined unified PCA model was created from the superset of all automatically fit training scans including all three devices. Body composition predictions to DXA measurements were learned from the training mesh PCA coefficients using linear regression. Using this final unified model, we tested the accuracy of our body composition models on a withheld sample of 562 scans by fitting a PCA parameterized template mesh to each raw scan and predicting the expected body composition metrics from the principal components using the learned regression model., Results: We achieved coefficients of determination (R 2 ) above 0.8 on all nine fat and lean predictions except female visceral fat (0.77). R 2 was as high as 0.94 (total fat and lean, trunk fat), and all root-mean-squared errors were below 3.0 kg. All predicted body composition variables were not significantly different from reference DXA measurements except for visceral fat and female trunk fat. Repeatability precision as measured by the coefficient of variation (%CV) was around 2-3x worse than DXA precision, with visceral fat %CV below 2x DXA %CV and female total fat mass at 5x., Conclusions: Our method provides an accurate, automated, and scanner agnostic framework for standardizing 3DO scans and a low cost, radiation-free alternative to criterion radiology imaging for body composition analysis. We published a web-app version of this work at https://shapeup.shepherdresearchlab.org/3do-bodycomp-analyzer/ that accepts mesh file uploads and returns templated meshes with body composition predictions for demo purposes., (© 2022 American Association of Physicists in Medicine.)

Background and Objective: Skeletal muscle is critical for overall health and predicts quality of life in several chronic diseases, thus quantification of muscle mass and composition is necessary to understand how interventions promote changes in muscle quality. The purpose of this investigation was to quantify changes in muscle mass and composition in two distinct pre-clinical models of changes in muscle quality using a clinical dual X-ray absorptiometry (DEXA), validated for use in mice. Materials and Methods: Adult C57Bl6 male mice were given running wheels (RUN; muscle hypertrophy) or placed in hypobaric hypoxia (HH; muscle atrophy) for four weeks. Animals received weekly DEXA and terminal collection of muscle hind limb complex (HLC) and quadriceps weights and signaling for molecular regulators of muscle mass and composition. Results : HH decreased total HLC muscle mass with no changes in muscle composition. RUN induced loss of fat mass in both the quadriceps and HLC. Molecular mediators of atrophy were upregulated in HH while stimulators of muscle growth were higher in RUN. These changes in muscle mass and composition were quantified by a clinical DEXA, which we described and validated for use in pre-clinical models. Conclusions: RUN improves muscle composition while HH promotes muscle atrophy, though changes in composition in hypoxia remain unclear. Use of the widely available clinical DEXA for use in mice enhances translational research capacity to understand the mechanisms by which atrophy and hypertrophy promote skeletal muscle and overall health.

Fat-free mass as well as lean soft tissue mass is a surrogate for skeletal muscle mass and is often used for the normalization of several physiological variables or for the diagnosing of low muscle mass in older adults. However, both fat-free mass and lean tissue mass include nonskeletal muscle components such as the fat-free component of adipose tissue fat cells. A technique known as water-fat MRI provides a noninvasive and radiation-free assessment of the fat-free component of adipose tissue in humans. However, if this method is impractical or unavailable, some authors suggest that a constant value for the fat-free component of adipose tissue can be used as an indirect estimate. The purpose of this review is to examine the fat fraction percentage of white (subcutaneous) adipose tissue in adolescents and young/middle-aged/older adults measured by water-fat MRI and provide discussion on how the fat-free adipose tissue values from the water-fat separation method compare with the constant value used in previous studies. Calculated mean values for the percentage of fat fraction in subcutaneous adipose tissue were 86.9% in the overall sample, 86.4% in adolescents (3 studies), and 87.1% in young, middle-aged and older adults (7 studies). This is similar to the 85% value proposed in the classical studies but in the majority of studies the 85% estimate was outside of the 95% confidence interval (CI) of the water-fat MRI estimate. There may be several factors to consider that may affect the fat fraction percentage (e.g. reliability of the MRI estimate, age, sex, obesity, etc.), however, at this time there is insufficient evidence to determine the effect of each of these variables. If the measurement is reliable, then this might suggest that the 85% constant may need to be altered to better reflect the water-fat MRI estimate., (Copyright © 2018 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

The purpose of the present study was to generate normative values for total and regional body composition in male and female Division 1 collegiate track and field athletes using dual X-ray absorptiometry. We also sought to examine body composition by event and sex. Data were used from the Consortium of College Athlete Research group. A total of 590 (male [M]/female [F] = 274/316) athletes had their height, weight, total and regional fat mass (FM), lean mass, and bone mineral density (BMD) measured. Athletes were classified into 1 of 7 categories: Jumps (M/F = 28/30); Long Distance (M/F = 104/110), Middle Distance (M/F = 27/24), Multievent (M/F = 11/9), Pole Vault (M/F = 21/27), Sprints (M/F = 54/96), and Throws (M/F = 29/20). Total and regional differences between events and sex were assessed by analysis of variance. Except for male and female throwers, all other track and field athletes' mean percent body fat (M: 10.3%-12.6%, F: 17.5%-21.6%) and visceral FM (<500 g) was low, but in a healthy range. As expected, throwers had significantly (p < 0.05) higher total and regional FM and lean mass than other events. In addition, male (1.55 ± 0.11 g/cm 2 ) and female (1.40 ± 0.12 g/cm 2 ) throwers had significantly greater BMD than all other events while male (1.25 ± 0.10 g/cm 2 ) and female (1.16 ± 0.09 g/cm 2 ) distance runners had significantly lower BMD than all other events. In conclusion, track athletes' body composition differed across events for both males and females. These measurements provide normative data on NCAA Division 1 male and female track and field athletes., (Copyright © 2019 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

Background: Cystic fibrosis (CF) is characterized by changes in fat mass and lean body mass that may have important prognostic value. We aim to appraise the type and frequency of application of body composition (BC) methods in child and adult patients with CF., Methods: We used 4 databases (Embase, PubMed, Scopus, and Web of Science) to perform the literature search. The search was conducted from January 2017 to February 2017. Two independent reviewers selected articles based on titles and abstracts to check eligibility for inclusion. All study designs or types of articles (abstract, full text) were considered., Results: Eighty-four full-text articles and 40 studies presented only as abstracts were selected. Sixty-four studies included children and adolescents (age range of 0.1-18 years), and 41 studies recruited adults (range of 18-57 years); 13 studies included both age groups. Dual-energy X-ray absorptiometry (DXA) was used in 56 studies (33.9%), and bioelectric impedance analysis (BIA) was used in 12 studies (9.7%), whereas 38 studies (30.6%) combined different methods (up to 5 different methods) to assess BC., Conclusions: The results show a large variability in the application of BC methods in patients with CF that makes the comparison between studies difficult. The only methods with a sufficient body of literature are DXA and BIA., (© 2019 American Society for Parenteral and Enteral Nutrition.)

Background: To date, the accuracy of bio-impedance (BIA) to assess body composition & sarcopenia in persons aged 80 and over remains unclear., Objective: We aimed to evaluate the agreement between dual energy X-ray absorptiometry (DXA) and BIA equations to determine lean mass, as well as their suitability to identify sarcopenia., Design: 174 community dwelling well-functioning persons (83 women, 91 men) aged 80 and over were included. Appendicular lean mass (ALM) was predicted using BIA-based equations available in literature, and compared to DXA outcomes. Through cross-validation and stepwise multiple linear regression, a new ALM-formula was generated suitable for this population., Results: Literature-based BIA equations systematically overestimated ALM. The new prediction formula that we propose for the 80+ is: ALM = 0,827+(0,19*Impedance Index)+(2,101*Sex)+(0,079*Weight); R 2  = 0,888; SEE = 1,450 kg. Sarcopenia classification based on our new BIA equation for ALM showed better agreement with DXA (k ≥ 0,454) compared to literature-based BIA equations (k < 0,368)., Conclusions: Despite the high correlation between both methods, literature-based BIA equations consistently overestimate ALM compared to DXA in persons aged 80 and over. We proposed a new equation for ALM, reaching higher agreement with DXA and thus improving the accuracy of BIA for this specific age group., (Copyright © 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

The aim of this study was to explore the reliability and precision of body compartment measures, in particular visceral adipose tissue, in weight stable adults over a range of BMIs using GE-Lunar iDXA. Weight-stable participants aged 18⁻65 years had a total body composition scan on GE-Lunar iDXA either on three separate occasions over a three month period ( n = 51), or on a single occasion for duplicate scans with repositioning ( n = 30). The coefficient of variation (CV%) and least significant change (LSC) of body compartments were calculated. The CV was higher for all measures over three months (range 0.8⁻5.9%) compared with same-day precision-scans (all < 2%). The CV for visceral adipose tissue (VAT) was considerably higher than all other body compartments (42.2% three months, 16.2% same day scanning). To accurately measure VAT mass using the GE iDXA it is recommended that participants have a BMI ≥ 25 kg/m², or VAT mass > 500 g. Changes observed in VAT mass levels below 500 g should be interpreted with caution due to lack of precision and reliability. All other compartmental measures demonstrated good reliability, with less than 6% variation over three months.

This study aimed to compare the use of the bioelectrical impedance device (BIA) seca ® mBCA 515 using dual X-ray absorptiometry (DXA) as a reference method, for body composition assessment in adults across the spectrum of body mass indices. It explores the utility of simple anthropometric measures (the waist height ratio (WHtR) and waist circumference (WC)) for the assessment of obesity. In the morning after an overnight fast (10 h), 30 participants underwent a body composition DXA (GE iDXA) scan, BIA (seca 515), and anthropometric measures. Compared to the DXA reference measure, the BIA underestimated fat mass (FM) by 0.32 kg (limits of agreement -3.8 kg, 4.4 kg); overestimated fat free mass (FFM) by 0.43 kg (limits of agreement -8.2 kg, 4.3 kg). Some of the variation was explained by body mass index (BMI), as for FM, the mean difference of the normal range BMI group was smaller than for the overweight/obese group (0.25 kg and 0.35 kg, respectively) with wider limits of agreement (-4.30 kg, 4.81 kg, and -3.61 kg, 4.30 kg, respectively). There were significant differences in visceral adipose tissue (VAT) volume measurements between methods with BIA systematically overestimating VAT compared to DXA. WC was more strongly correlated with DXA FM (rho = 0.90, p < 0.001) than WHtR (rho = 0.83, p < 0.001). BIA had some agreement with DXA; however, they are not equivalent measures for the range of BMIs explored, with DXA remaining the more informative tool. WC is a useful and simple assessment tool for obesity.

Objective: To analyze the associations between body composition, notably low lean mass, and clinical symptoms [pain, physical function, quality of life (QoL)] in patients with symptomatic hip and/or knee OA., Methods: Cross-sectional study using data from the 3-year follow-up visit of the Knee and Hip OsteoArthritis Long-term assessment (KHOALA) cohort. Skeletal muscle and fat mass were measured by dual X-ray absorptiometry (DXA). Fat mass index (FMI) was defined as total fat mass/height 2 . Appendicular lean mass was adjusted on body mass index (ALM/BMI), and low lean mass was defined according to the definition of FNIH Sarcopenia Project recommendations. Pain and function were measured by the WOMAC index and QoL by the SF-36., Results: In total, 358 patients underwent DXA (67% women, mean [SD] age 63.4 [8.4] years, mean BMI 29.5 [5.6]kg/m 2 ). The visual analog scale (0-100) pain score was 38.0 [24.7] and 25.4% had hip and 74.6% knee OA. Low lean mass and ALM/BMI were associated with impaired QoL and WOMAC scores on bivariate analysis (all p ≤ 0.001) but not on multivariate analysis after adjustment for FMI. For patients with normal BMI, mean [SD] WOMAC scores were higher (greater impairment) with low lean mass than normal body composition (WOMAC function 33.4 [23.3] and 24.0 [17.4], p = 0.02), and mean SF-36 physical component score was lower (greater impairment) 40.3 [10.2] and (44.3 [8.4], p = 0.04). Among patients with obesity, low lean mass had no additional effect., Conclusion: For patients with OA and normal BMI, QoL and function were more impaired for those with than without low lean mass. Conserving muscle mass in people with OA could have functional and antalgic benefits especially for those with normal BMI., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to compare the accuracy of measurements of body composition made using dual x-ray absorptiometry (DXA), analysis of computed tomography (CT) scans at the L3 vertebral level, and bioelectrical impedance analysis (BIA)., Methods: DXA, CT, and BIA were performed in 47 patients recruited from two clinical trials investigating metabolic changes associated with major abdominal surgery or neoadjuvant chemotherapy for esophagogastric cancer. DXA was performed the week before surgery and before and after commencement of neoadjuvant chemotherapy. BIA was performed at the same time points and used with standard equations to calculate fat-free mass (FFM). Analysis of CT scans performed within 3 mo of the study was used to estimate FFM and fat mass (FM)., Results: There was good correlation between FM on DXA and CT (r 2  = 0.6632; P < 0.0001) and FFM on DXA and CT (r 2  = 0.7634; P < 0.0001), as well as FFM on DXA and BIA (r 2  = 0.6275; P < 0.0001). Correlation between FFM on CT and BIA also was significant (r 2  = 0.2742; P < 0.0001). On Bland-Altman analysis, average bias for FM on DXA and CT was 0.2564 with 95% limits of agreement (LOA) of -9.451 to 9.964. For FFM on DXA and CT, average bias was -0.1477, with LOA of -8.621 to 8.325. For FFM on DXA and BIA, average bias was -3.792, with LOA of -15.52 to 7.936. For FFM on CT and BIA, average bias was -2.661, with LOA of -22.71 to 17.39., Conclusion: Although a systematic error underestimating FFM was demonstrated with BIA, it may be a useful modality to quantify body composition in the clinical situation., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To evaluate the accuracy of estimated fat mass and fat-free mass from bedside methods compared with reference methods in children with chronic illnesses., Study Design: Fat mass and fat-free mass values were obtained by skinfold, bioelectrical impedance analysis (BIA), dual-energy x-ray absorptiometry (DXA), and deuterium dilution method in children with spinal muscular atrophy, intestinal failure, and post hematopoietic stem cell transplantation (HSCT). Spearman's correlation and agreement analyses were performed between (1) fat mass values estimated by skinfold equations and by DXA and (2) fat-free mass values estimated by BIA equations and by DXA and deuterium dilution methods. Limits of agreement between estimating and reference methods within ±20% were deemed clinically acceptable., Results: Fat mass and fat-free mass values from 90 measurements in 56 patients, 55% male, and median age of 11.6 years were analyzed. Correlation coefficients between the skinfold-estimated fat mass values and DXA were 0.93-0.94 and between BIA-estimated fat-free mass values and DXA were 0.92-0.97. Limits of agreement between estimated and DXA values of fat mass and fat-free mass were greater than ±20% for all equations. Correlation coefficients between estimated fat-free mass values and deuterium dilution method in 35 encounters were 0.87-0.91, and limits of agreement were greater than ±20%., Conclusion: Estimated body composition values derived from skinfold and BIA may not be reliable in children with chronic illnesses. An accurate noninvasive method to estimate body composition in this cohort is desirable., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Infant adiposity better predicts childhood obesity/metabolic risk than weight, but technical challenges fuel controversy over the accuracy of adiposity estimates., Objective: We prospectively measured adiposity (%fat) in term newborns (NB) at 2 weeks (n = 41) and 1 year (n = 30)., Methods: %fat was measured by dual X-ray absorptiometry (DXA), PEAPOD and skin-folds (SF). DXAs were analyzed using Hologic Apex software 3.2(DXAv1) and a new version 5.5.2(DXAv2)., Results: NB %fat by DXAv2 was 55% higher than DXAv1 (14.2% vs. 9.1%), 45% higher than SF (9.8%), and 36% higher than PEAPOD (10.4%). Among NB, Pearson correlations were 0.73-0.89, but agreement (intra-class correlations) poor between DXAv2 and DXAv1 (0.527), SF (0.354) and PEAPOD (0.618). At 1 year, %fat by DXAv2 was 51% higher than DXAv1 (33.6% vs. 22.4%), and twice as high compared with SF (14.6%). Agreement was poor between DXAv2 and DXAv1 (0.204), and SF (0.038). The absolute increase in %fat from 2 weeks to 1 year was 19.7% (DXAv2), 13.6% (DXAv1) and only 4.8% by SF., Conclusion: Analysis of the same DXA scans using new software yielded considerably higher adiposity estimates at birth and 1 year compared with the previous version. Using different modalities to assess body composition longitudinally is problematic. Standardization is gravely needed to determine how early life exposures affect childhood obesity/metabolic risk., (© 2015 World Obesity.)

Percentage fat (%FM) and fat-free mass (FFM) were measured in 37 children from a sports academy and in 71 children from standard schools with dual x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) using the manufacturer's equation (Tanita) and an ethnic-specific prediction equation (Haroun). In the standard school, BIA overestimated FFM and underestimated %FM by a mean of 2.5 kg and 5.2%, respectively, using the Tanita equation. In girls from the sports academy, the Tanita equation underestimated FFM and overestimated %FM compared with DXA (mean difference BIA-DXA; FFM: -1.3 kg; %FM: 1.8%). The Haroun equation improved mean agreement between BIA and DXA in children (11 to 15 years) from the sports academy and for boys from standard schools, but reduced accuracy on individual assessments. These results have important practice implications for dietetics practitioners specializing in sports nutrition and exercise trainers., (Copyright © 2014 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.)

Objective: Obesity is a result of chronic overconsumption of calories relative to the amount of energy expended. While fat free mass can account for ~80% of the variance in energy expenditure, there is still considerable variability in energy requirements between individuals that cannot be explained. We hypothesized that responsiveness to the recently discovered myokine, irisin, which has been touted to increase energy expenditure via activation of brown adipocytes in rodents and possibly humans, may explain some of the variability in energy expenditure., Materials/methods: Post-menopausal women (n=17) spent 24-h in a whole room indirect calorimeter. During the study day, subjects remained sedentary and consumed meals tailored to their energy requirements. Plasma irisin, leptin and adiponectin were measured in samples taken from each subject., Results: Our results suggest that in general, irisin levels do not correlate with 24-h energy expenditure, however, for a subpopulation irisin levels and energy expenditure are highly correlative., Conclusion: Irisin may help explain some of the observed variability in individual energy requirements that cannot be accounted for by fat free mass. Therefore, interventions designed to increase irisin action may prove to be promising avenues for the treatment of obesity., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The purpose of this study was to compare the muscle-to-bone ratio (MBR) in National Collegiate Athletic Association Division I football players (collegiate football players [CFP]) to healthy, age-matched controls. In addition, we examined MBR in CFP by position. A total of 553 CFP and 261 controls had their total and regional lean mass (LM), fat mass (FM), and bone mineral content (BMC) determined by dual x-ray absorptiometry (DXA). College football players were categorized by positions defined as offensive linemen (OL), defensive linemen (DL), tight end, linebacker (LB), running back (RB), punter or kicker, quarterback (QB), defensive back (DB), and wide receiver (WR). There were significant differences between CFP and controls for total LM (80.1 ± 10.0 vs. 56.9 ± 7.8 kg), FM (22.2 ± 12.5 vs. 15.2 ± 7.1 kg), and BMC (4.3 ± 0.5 vs. 3.1 ± 0.5 kg). Although there were significant differences in body composition between CFP and controls, there was no significant differences in total MBR between CFP and controls (18.6 ± 1.4 vs. 18.8 ± 1.7). Regionally, CFP had significantly lower trunk MBR than controls (26.7 ± 2.7 vs. 28.7 ± 4.2), but no difference was seen in leg or arm MBR. Positional differences in CFP were noted as total MBR being significantly higher in DL (19.0 ± 1.4) than in DB (18.1 ± 1.3), WR (18.1 ± 1.3), and LB (18.2 ± 1.3). OL had a significantly higher total MBR (19.2 ± 1.3) than DB(18.1 ± 1.3), LB (18.2 ± 1.3), QB (18.1 ± 1.0), and WR (18.1 ± 1.3). In addition, RB had significantly higher total MBR (18.8 ± 1.3) than DB (18.1 ± 1.3) and WR (18.1 ± 1.3). This study may provide athletes and training staff with normative values when evaluating total and regional MBR with DXA. [ABSTRACT FROM AUTHOR]

BackgroundNew recommendations for the assessment of malnutrition and sarcopenia include body composition, specifically reduced muscle mass. Three-dimensional optical imaging (3DO) is a validated, accessible, and affordable alternative to dual X-ray absorptiometry (DXA).ObjectiveIdentify strengths and weaknesses of 3DO for identification of malnutrition in participants with low body mass index (BMI) and eating disorders.DesignParticipants were enrolled in the cross-sectional Shape Up! Adults and Kids studies of body shape, metabolic risk, and functional assessment and had BMI of

Background: To examine substrate oxidation in prepubertal and early pubertal children as a function of body weight, body composition, and sex during an exhaustive cycling test. Methods: This study included 320 children in prepubertal and early puberty (Tanner stage 1 or 2; n = 188 males) who completed a minimum of 4 stages (2–5 min/stage) of an adapted version of the McMaster exhaustive exercise protocol on an upright cycle ergometer. Substrate utilization, relative to individual VO2peak, was determined using VO2 and VCO2 data, obtained with breath-by-breath gas analysis during exercise. Results: Both peak (mg/kg lean body mass·min) and submaximal lipid oxidation (mg/kg lean body mass·min) were highest (P <.01) in children with healthy weight (HW), then overweight, and lowest in obese (OB). Both females with HW (compared with males with HW) and females with OB (compared with males with OB) had higher (P <.01) peak and submaximal lipid oxidation. In children with OB, fat-free mass correlated positively (P <.01) with submaximal lipid oxidation (r =.50). In contrast, in children with HW and overweight, fat-free mass correlated positively (P <.01) with carbohydrate oxidation (r =.52 and r =.47, respectively). Conclusion: Obesity during childhood may alter substrate oxidation during exercise. These results may have implications in the implementation of exercise programs in prepubertal or early puberty to control adiposity. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to examine the muscle-to-bone ratio (MBR) in National Football League (NFL) players. Three hundred and forty-six NFL players had their total body lean, fat and bone masses determined using dual X-ray absorptiometry and were compared to 228 age-matched, healthy male controls. Compared to the control group, NFL players had a significantly lower percent total body fat (17.90±6.92 vs. 22.93±8.96%, p=0.053), but significantly greater total fat mass (19.76±11.29 vs. 17.84±12.11 kg, p<0.0001), lean mass (84.55±8.75 vs. 55.3±11.79 kg, p<0.0001), bone mineral content (4.58±0.45 vs. 2.91±0.67 kg, p<0.0001), and bone mineral density (1.61±0.11 vs. 1.26±0.21 g/cm2 , p<0.0001). NFL players had greater arm MBR (17.70±1.47 vs. 16.48±1.88, p<0.0001) than controls; however, both trunk (26.62±2.55 vs. 31.56±4.19, p<0.0001) and total (18.50±1.31 vs. 19.12±1.88, p<0.001) MBR were lower in NFL players. Leg MBR was not significantly different between NFL players and controls (16.72±1.53 vs. 16.85±1.87, p=0.34). When NFL players were categorized by their offensive or defensive position for comparison, no differences in total MBR were observed. However, leg MBR varied greatly among NFL players by position. It is possible that regional differences in MBR in the NFL players may be related to the demands of that position. [ABSTRACT FROM AUTHOR]

Purpose: Electrocardiogram (ECG) QRS voltages correlate poorly with left ventricular mass (LVM). Body composition explains some of the QRS voltage variability. The relation between QRS voltages, LVM and body composition in endurance athletes is unknown. Methods: Elite endurance athletes from the Pro@Heart trial were evaluated with 12-lead ECG for Cornell and Sokolow-Lyon voltage and product. Cardiac magnetic resonance imaging assessed LVM. Dual energy x-ray absorptiometry assessed fat mass (FM) and lean mass of the trunk and whole body (LBM). The determinants of QRS voltages and LVM were identified by multivariable linear regression. Models combining ECG, demographics, DEXA and exercise capacity to predict LVM were developed. Results: In 122 athletes (19 years, 71.3% male) LVM was a determinant of the Sokolow-Lyon voltage and product (β = 0.334 and 0.477, p < 0.001) but not of the Cornell criteria. FM of the trunk (β = − 0.186 and − 0.180, p < 0.05) negatively influenced the Cornell voltage and product but not the Sokolow-Lyon criteria. DEXA marginally improved the prediction of LVM by ECG (r = 0.773 vs 0.510, p < 0.001; RMSE = 18.9 ± 13.8 vs 25.5 ± 18.7 g, p > 0.05) with LBM as the strongest predictor (β = 0.664, p < 0.001). DEXA did not improve the prediction of LVM by ECG and demographics combined and LVM was best predicted by including VO2max (r = 0.845, RMSE = 15.9 ± 11.6 g). Conclusion: LVM correlates poorly with QRS voltages with adipose tissue as a minor determinant in elite endurance athletes. LBM is the strongest single predictor of LVM but only marginally improves LVM prediction beyond ECG variables. In endurance athletes, LVM is best predicted by combining ECG, demographics and VO2max. [ABSTRACT FROM AUTHOR]

Pompe disease is a rare autosomal recessive disorder caused by the deficiency of acid α-glycosidase resulting in accumulation of glycogen in the lysosomes. The late-onset form of the disease (LOPD) causes primarily progressive muscle weakness and respiratory insufficiency. Enzyme replacement therapy (ERT) introduced in 2006, showed mild improvement or stabilization of the symptoms although long-term data are limited. Aim of the study was to describe the progression of body composition and walking ability in LOPD patients receiving ERT consistently for 9 years. Lean body mass, bone mineral density, body fat and 6 min walking distance were assessed in three male and three female LOPD patients (height 165.8 ± 11.2 cm, age 42.3 ± 11.8yrs, body mass 71.1 ± 20.8 kg, at study entry), every three years, for 9 years since ERT initiation (T0, T3, T6, T9). Total body and upper extremities' lean mass remained unchanged (p < 0.05), but it was decreased for the lower extremities (T3:13.06 ± 3.848 kg vs. T9:11.63 ± 3.49 kg, p < 0.05). Lean body mass was not significantly different after 9 years of ERT compared to before the ERT initiation (T0 to T9). Bone mineral density remained unchanged. Percent body fat increased (T0:39.1 ± 10.3%, vs. T9:43.1 ± 10.4%, p < 0.05). Six minute walking distance tended to increase after 3 years of ERT and decreased gradually thereafter, with no difference between T0-T9. Lean mass of the lower extremities adjusted for body weight was significantly correlated with 6 min walking distance (r = 0.712, p < 0.05). The current data show that enzyme replacement therapy may preserve lean body mass, bone mineral density and walking capacity in LOPD patients. [ABSTRACT FROM AUTHOR]

Czeck, MA, Roelofs, EJ, Evanoff, NG, and Dengel, DR. No Changes in body composition in NCAA Division I Collegiate Football Players due to COVID-19 restrictions. J Strength Cond Res 36(6): 1749–1752, 2022—The purpose of this study was to explore the impact of coronavirus disease 2019 (COVID-19) restrictions on body composition, assessed by dual x-ray absorptiometry (DXA), between the 2020 postseason (pre–COVID-19 restrictions) and the 2021 postseason (post–COVID-19 restrictions) in collegiate football players (n = 50). In addition, a subset of athletes (n = 23) was used to explore body composition variables across 4 postseason time points. Body composition variables assessed were total and regional body fat percent, total mass, lean mass, fat mass, bone mineral content, bone mineral density, and visceral adipose tissue mass. Paired t -tests were used to determine differences between the 2020 postseason and the 2021 postseason in body composition variables. Analysis of variance with Tukey HSD post hoc tests assessed significant differences in total and regional body composition across 4 years while adjusting for multiple comparisons. There were no significant differences (p > 0.05) between postseason 2020 and postseason 2021 for all measures of body composition. In a subset of athletes, body composition was analyzed over a 4-year period of time. There were no significant differences between all 4 time points for all measures of body composition. In conclusion, body composition variables in this study's subjects were not affected because of coronavirus disease 2019 restrictions or over 4 years of their collegiate football career. [ABSTRACT FROM AUTHOR]

Wichmann, TK, Wolfson, J, Roelofs, EJ, Bosch, TA, Bach, CW, Oliver, JM, Carbuhn, A, Stanforth, PR, and Dengel, DR. Longitudinal assessment of NCAA Division I football body composition by season and player age. J Strength Cond Res 36(6): 1682–1690, 2022—The purpose of this study was to examine longitudinal body composition changes by position, categorized by season and age, using dual X-ray absorptiometry in NCAA Division I football players. Seven hundred nineteen collegiate male football players aged 18–22 years ( X ¯ age ± SE = 19.4 ± 0.05 years) were examined. Percent body fat (%BF), fat mass (FM), lean mass (LM), total body mass (TM), bone mineral density (BMD), and visceral adipose tissue (VAT) were measured. Players were categorized into position groups of Linemen, Big Skill, Skill, or Special Team. One player scan was used per season (preseason, postseason, and spring season). Analysis of variance and Tukey HSD assessed total and regional differences across age, position groups, and seasons (significance of p < 0.05). Linemen had the greatest FM and LM measures compared with other groups for season and age. From preseason to postseason, %BF, FM, LM, and BMD significantly decreased for each position group. From postseason to spring season, %BF, FM, and VAT decreased, whereas LM increased within each position group. FM, VAT, LM, and TM increased with age in all position groups. The findings of this study indicate that body composition significantly worsened from preseason to postseason and improved from the preseason and postseason to the spring season. [ABSTRACT FROM AUTHOR]

Czeck, MA, Roelofs, EJ, Dietz, C, Bosch, TA, and Dengel, DR. Body composition and on-ice skate times for NCAA Division I collegiate male and female ice hockey athletes. J Strength Cond Res 36(1): 187–192, 2022—This study's purpose was to explore positional differences for an on-ice timed skate test and its relationship to body composition. Male (n = 15) and female (n = 18) collegiate hockey players participated in this study (total n = 33). Each player was categorized by position of forward or defensemen. Dual x-ray absorptiometry assessed total body composition variables of lean, fat, and bone mass as well as regional measures of lean mass, fat mass, and visceral adipose tissue. Total time and section times were determined for the on-ice skating test through a gated automatic timing system at 9, 18, 24, 42, 48, 66, 82, 132, and 148 m. Analysis of variance and Tukey's honest significance difference assessed on-ice skate time differences between positions (p ≤ 0.05). Correlations between body composition variables and skate times were determined for change of direction, skating time, linear skate time, and total skate time. There were no significant differences between positions for skate times (p > 0.05). Body fat percent (p = 0.007; r = 0.55), total fat mass (p = 0.027; r = 0.46), and leg fat mass (p = 0.019; 0.49) were significantly correlated with total skate time in men, whereas only body fat percent was significantly correlated with change of direction (p = 0.022; r = 0.54) and total skate times (p = 0.016; r = 0.56) in women. The total upper-body mass to leg lean mass ratio was significantly correlated with change of direction (p = 0.036; r = 0.50) in women. In conclusion, the results from this study suggest no differences between on-ice skating times between forwards and defensemen. However, body fat percentage was correlated with on-ice skate times in male and female collegiate hockey players. [ABSTRACT FROM AUTHOR]

Eighty-three male and female (49/34) athletes underwent determination of total fat mass (FM), lean mass (LM), bone mineral density (BMD) and visceral adipose tissue (VAT) by dual X-ray absorptiometry during the pre-season, in-season and off-season. Athletes were classified by position of Goalie (G; M/F=7/6), Forward (F; M/F=26/18), or Defenseman (D; M/F=16/10). In males, all positions were similar in weight, FM, LM, BMD and VAT. In females, F weighed less than D and G. FM and VAT was lower in F than D and G, but D was not different from G. LM was lower in F compared to D, but not G, with no differences between D and G. There were no differences in BMD between positions. There were no seasonal changes in males for body composition variables. In females, FM, LM and VAT decreased from pre-season to in-season, while BMD increased. From in-season to off-season, LM increased and BMD decreased. From off-season to pre-season, FM and VAT increased. In conclusion, there were no differences across position or seasonal changes in body composition in males. However, there were positional and seasonal changes in body composition in females, indicating possible differences in training regimens during the off-season compared to males. [ABSTRACT FROM AUTHOR]

The body composition phenotype of an athlete displays the complex interaction among genotype, physiological and metabolic demands of a sport, diet, and physical training. Observational studies dominate the literature and describe the sport-specific physique characteristics (size, shape, and composition) of adult athletes by gender and levels of competition. Limited data reveal how body composition measurements can benefit an athlete. Thus, the objective is to identify purposeful measurements of body composition, notably fat and lean muscle masses, and determine their impact on the health and performance of athletes. Areas of interest include relationships among total and regional body composition measurements, muscle function, sport-specific performance, risk of injury, return to sport after injury, and identification of activity-induced fluid shifts. Discussion includes the application of specific uses of dual X-ray absorptiometry and bioelectrical impedance including an emphasis on the need to minimize measurement errors and standardize protocols, and highlights opportunities for future research. This focus on functional body composition can benefit the health and optimize the performance of an athlete. [ABSTRACT FROM AUTHOR]

This cross-sectional study aimed to examine the degree of whole-body morphological asymmetries in female tennis players. Data were collected in 19 high-level female tennis players (21.3 ± 3.4 years). Based on anthropometric measurements (upper arm, lower arm, wrist, upper leg and lower leg circumferences as well as elbow and knee widths) and dual x-ray absorptiometry research scans (bone mineral density (BMD), bone mineral content (BMC), lean mass (LM), fat mass (FM) as well as humerus, radio-ulnar, femur and tibia bone lengths), within-subject morphological asymmetries for both upper (dominant vs. non-dominant) and lower (contralateral vs. ipsilateral) extremities were examined. Upper arm (p = 0.015), lower arm (p < 0.001) and wrist circumferences (p < 0.001), elbow width (p = 0.049), BMD (p < 0.001), BMC (p < 0.001), LM (p = 0.001), humerus (p = 0.003) and radio-ulnar bone length (p < 0.001) were all greater in the dominant upper extremity. BMC (p < 0.001) and LM (p < 0.001) were greater in the contralateral lower extremity, whereas FM (p = 0.028) was greater in the ipsilateral lower extremity. This is the first study to report significant side-to-side differences in both upper and lower extremities in high-level female tennis players. [ABSTRACT FROM AUTHOR]

The primary study objective was to measure positional differences in total and regional body composition among female NCAA Division I collegiate volleyball players using dual X-ray absorptiometry (DXA). The secondary objective was to examine normative age curves for fat and lean mass (LM) variables. Ninety female volleyball players from 5 universities received a DXA scan. Athletes were categorized by position: middle blocker (MB = 31), outside hitter (OH = 32), setter (ST = 9), and Libero (LB = 18). Height, body mass, total and regional fat mass (FM), LM, bone mineral density (BMD), and abdominal visceral adipose tissue were measured by DXA. Body mass distribution ratios were calculated. The secondary age analysis included a subset of 153 DXA scans (n = 83, ages 18-21 years). Front row players (i.e., MB and OH) had significantly greater total and regional LM and BMD measures (p < 0.05, all), compared with non-front row players (i.e., LB and ST). Differences in total LM (p,0.001) were significantly influenced by height. Front row players had consistently lower mass distribution ratios compared with non-front row players (p,0.05, all). Lean mass index (LMI, p50.752) and FM index (FMI, p = 0.392) were not significantly different across ages. Back row players have greater relative upper body mass, whereas mass in front row players is more evenly distributed between the upper and lower body. Bone mineral density differences may be influenced by repeated impact of jumping during the attacking and blocking actions of front row players. Minimal changes in LMI and fluctuations in FMI can be expected across an athlete's career. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine body composition of National Collegiate Athletic Association Division I female soccer players by position and season. One hundred seventy-five female athletes were categorized by positions of forward (n=47), midfielder (n=51), defender (n=57), and goalkeeper (n=20). A dual X-ray absorptiometry scan assessed percent body fat, total lean mass, total fat mass, arm and leg lean mass and fat mass, and visceral adipose tissue. Goalkeepers had significantly higher total, arm, and leg lean mass and fat mass compared to all other positions (p<0.05). For seasonal changes, body fat percentage was significantly higher in winter off-season (26.7%) compared to summer off-season (25.7%) and pre-season (25.8%; p<0.01) for all positions. Total and leg lean mass was significantly lower in winter off-season compared to all other seasons, and total lean mass was significantly higher in summer off-season than pre-season (p<0.01). Overall, goalkeepers were significantly different than all other positions. Body fat percentage increased and lean mass decreased in winter off-season indicating potential undesired changes in training and/or nutrition over the break whereas lean mass was the highest in summer off-season potentially reflecting the emphasis on resistance training and increased volume of training. [ABSTRACT FROM AUTHOR]

Abstract Background The body mass index (BMI) is a simple and widely utilized screening tool for obesity in children and adults. The purpose of this investigation was to evaluate if BMI could predict total fat mass (TFM) and percent body fat (%FAT) in a sample of overweight and obese children. Methods In this observational study, body composition was measured by dual energy x-ray absorptiometry (DXA) in 663 male and female overweight and obese children at baseline within a multidisciplinary, pediatric fitness clinic at an academic medical center. Univariate and multivariate regression analyses were conducted to evaluate whether BMI z-score (BMIz) predicts TFM or %FAT. Results The BMIz, sex and age of subjects were identified as significant predictors for both TFM and %FAT. In subjects younger than 9 years, the BMIz was a weak to moderate predictor for both TFM (R2 = 0.03 for males and 0.26 for females) and %FAT (R2 = 0.22 for males and 0.38 for females). For subjects between 9 and 18 years, the BMIz was a strong predictor for TFM (R2 between 0.57 and 0.73) while BMIz remained only moderately predictive for %FAT (R2 between 0.22 and 0.42). Conclusions These findings advance the understanding of the utility and limitations of BMI in children and adolescents. In youth (9-18y), BMIz is a strong predictor for TFM, but a weaker predictor of relative body fat (%FAT). In children younger than 9y, BMIz is only a weak to moderate predictor for both TFM and %FAT. This study cautions the use of BMIz as a predictor of %FAT in children younger than 9 years.

Background: Obesity in the United States is a serious and preventable health concern. Previous research suggests that habitual short sleep may influence obesity-risk behaviors, such as increased caloric intake, decreased physical activity and increased engagement in sedentary activities (e.g., media consumption, computer usage). Given that existing longitudinal research studies have methodological concerns preventing conclusive interpretations, Project STARLIT was designed to address these limitations and identify future intervention targets.Methods: A sample of young adults (n = 300) will be recruited during the summer prior to entering college. Participants will be screened for eligibility requirements prior to the inclusion in the Time 1 assessment though phone and in-person interviews. Once enrolled, participants will complete four assessments over a two year period (i.e., approximately 8, 16 and 24 months after Time 1). Each assessment will consist of one week of data collection including both objective (i.e., habitual sleep, physical activity, body fat composition) and subjective (i.e., sleep diary, 24-h food recall, technology use, and sleep-related beliefs/behaviors) measures.Discussion: Project STARLIT is designed to address methodological concerns of previous research. In addition to clarifying the relationship between habitual short sleep and weight gain among young adults, the proposed study will identify problematic obesity risk behaviors associated with habitual short sleep (e.g., increased caloric intake, physical/sedentary activity). The results will identify prevention or intervention targets related to obesity risk.Trial Registration: ClinicalTrials.gov NCT04100967, 9/23/19, Retrospectively registered. [ABSTRACT FROM AUTHOR]

Body composition and bone mineral density of Division 1 collegiate football players: a consortium of college athlete research study. J Strength Cond Res 33(5): 1 3 3 9 - 1346, 2 0 1 9 -T h e purpose of this study was to generate normative data for total and regional body composition in Division 1 collegiate football players using dual-energy x-ray absorptiometry (DXA) and examine positional differences in total and regional measurements. Data were used from the Consortium of College Athlete Research (C-CAR) group. Four hundred sixty-seven players were included in this study. Height, body mass, total and regional fat mass, lean mass, and bone mineral density were measured in each athlete in the preseason (June- August). Players were categorized by their offensive or defensive position for comparisons. Linemen tended to have the higher fat and lean mass measures (p < 0.05 for all) compared with other positions. Positions that mirror each other (e.g. linemen) had similar body composition and body ratios. All positions were classified as overweight or obese based on body mass index (BMI) (> 2 5 k g - r r r 2), yet other than offensive and defensive linemen, all positions had healthy percent body fat (1 3 -2 0% ) and low visceral fat mass (< 5 0 0 g). The data presented here provide normative positional data for total and regional fat mass, lean mass, and bone density in Division 1 collegiate football players. Player position had a significant effect on body composition measures and is likely associated with on-field positional requirements. From a player's health perspective, although all positions had relatively high BMI values, most positions had relatively low body fat and visceral fat, which is important for the health of players during and after their playing career. The increased accuracy and reliability of DXA provides greater information, regarding positional differences in college football players compared with other methods. [ABSTRACT FROM AUTHOR]

To examine measures of total and regional body composition using dual X-ray absorptiometry (DXA) in NCAA Division I collegiate equestrian athletes, 31 female collegiate equestrian athletes were matched to a population of normal controls by age and body mass index. Total and regional fat tissue mass (FM), lean tissue mass (LM), bone mineral density (BMD), and abdominal visceral adipose tissue (VAT) were measured by DXA. Equestrian athletes had a significantly (p=0.03) lower total body fat percentage (%fat) than controls. There were no significant differences in total LM and VAT between equestrian athletes and controls. However, equestrian athletes, when compared to the controls, had significantly lower leg %fat, leg FM and higher leg LM. The greater leg LM in equestrian riders resulted in a smaller upper to lower body LM ratio compared to controls. There was no difference in leg BMD between equestrian athletes and controls. There were no significant differences between the 2 styles of riding (i. e., hunt seat and western style) in regards to body composition. The lower total %fat in equestrian athletes seems to be influenced by differences in leg composition, with equestrian athletes having significantly more LM and less FM. [ABSTRACT FROM AUTHOR]

This study determined the most effective field method for quantifying body fat percentage in male elite youth soccer players and developed prediction equations based on anthropometric variables. Forty-four male elite-standard youth soccer players aged 16.3-18.0 years underwent body fat percentage assessments, including bioelectrical impedance analysis and the calculation of various skinfold-based prediction equations. Dual X-ray absorptiometry provided a criterion measure of body fat percentage. Correlation coefficients, bias, limits of agreement, and differences were used as validity measures, and regression analyses were used to develop soccer-specific prediction equations. The equations from Sarria et al. (1998) and Durnin & Rahaman (1967) reached very large correlations and the lowest biases, and they reached neither the practically worthwhile difference nor the substantial difference between methods. The new youth soccer-specific skinfold equation included a combination of triceps and supraspinale skinfolds. None of the practical methods compared in this study are adequate for estimating body fat percentage in male elite youth soccer players, except for the equations from Sarria et al. (1998) and Durnin & Rahaman (1967). The new youth soccer-specific equation calculated in this investigation is the only field method specifically developed and validated in elite male players, and it shows potentially good predictive power. [ABSTRACT FROM AUTHOR]

As the successor of Dual Photon Absorptiometry (DPA), Dual X-ray Absorptiometry (DXA) has seen 30 years of continuous technological innovations. Implementation of measures for standardization and quality assurance made DXA a reliable and clinically useful approach. Its use in clinical multicenter drug studies in osteoporosis lead to general acceptance as the standard technique of bone densitometry. The limitations of DXA are well established. As a measure of areal bone mineral density (aBMD) it depends on bone size and is biased by overlaying soft tissue and calcified structures. To some extent these errors can be reduced by estimation of bone depth and/or lateral imaging. DXA based aBMD can be supplemented by additional information obtainable from DXA scans: geometric indices such as hip axis length or complex models like 2-D finite element analysis have been developed and tested. Given the drastic improvement in image quality current DXA scans can be used for Vertebral Fracture Analysis (VFA) or grading of Abdominal Aortic Calcifications. A textural measure, Trabecular Bone Score (TBS) provides independent information on fracture risk. DXA devices can also be used for assessments beyond bone density. Periprosthetic aBMD changes can be monitored to study the mechanical fitting of bone implants. Total body composition measurements are increasingly being used in studies on nutrition, obesity, and sarcopenia. 30 years after its inception DXA is the undisputed standard imaging technique for the assessment of osteoporotic fracture risk with new applications beyond bone densitometry adding to its value. [ABSTRACT FROM AUTHOR]

Background: The body mass index (BMI) is a simple and widely utilized screening tool for obesity in children and adults. The purpose of this investigation was to evaluate if BMI could predict total fat mass (TFM) and percent body fat (%FAT) in a sample of overweight and obese children.Methods: In this observational study, body composition was measured by dual energy x-ray absorptiometry (DXA) in 663 male and female overweight and obese children at baseline within a multidisciplinary, pediatric fitness clinic at an academic medical center. Univariate and multivariate regression analyses were conducted to evaluate whether BMI z-score (BMIz) predicts TFM or %FAT.Results: The BMIz, sex and age of subjects were identified as significant predictors for both TFM and %FAT. In subjects younger than 9 years, the BMIz was a weak to moderate predictor for both TFM (R2 = 0.03 for males and 0.26 for females) and %FAT (R2 = 0.22 for males and 0.38 for females). For subjects between 9 and 18 years, the BMIz was a strong predictor for TFM (R2 between 0.57 and 0.73) while BMIz remained only moderately predictive for %FAT (R2 between 0.22 and 0.42).Conclusions: These findings advance the understanding of the utility and limitations of BMI in children and adolescents. In youth (9-18y), BMIz is a strong predictor for TFM, but a weaker predictor of relative body fat (%FAT). In children younger than 9y, BMIz is only a weak to moderate predictor for both TFM and %FAT. This study cautions the use of BMIz as a predictor of %FAT in children younger than 9 years. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the accuracy and reliability of a novel dual-energy x-ray absorptiometry (DXA) scanning method in the frontal plane for total, fat, and lean mass quantification of the anterior and posterior upper leg compartments. Methods: Twenty-one (11 females; ...age = 20.3 ± 1.3 yr) college athletes were assessed for total and regional body composition using DXA. The segmentation of anterior/posterior thigh compartments was measured with participants lying on their right and left sides and the scanned leg elevated with two foam pads. Custom regions of interest (ROIs) were created manually with enCore™ software for each scan using bony landmarks to quantify lean, fat, and total masses. Paired t-tests assessed this novel positioning method's accuracy against standard positioning. Intraclass correlation coefficients and coefficients of variation examined inter- and intrarater reliability for lateral scan measures of total, fat, and lean masses from manually created ROIs. Results: All mean ± SD differences between frontal and lateral DXA scans of right (R) and left (L) leg total mass (R: 8.42 ± 195.57 g; L: 19.47 ± 131.80 g), fat mass (R: 61.26 ± 215.66 g; L: -5.89 ± 239.97 g), and lean mass (R: -103.00 ± 302.54 g; L: -27.58 ± 288.14 g) were nonsignificant (P value range = 0.15-0.91). Intraclass correlation coefficients were high for all composition measures between and within raters, ranging from 0.983 to 0.999 and from 0.954 to 0.999, respectively, with low variation across measures (all coefficients of variation ≤ 5%). Conclusion: The results of this study suggest that DXA measures using lateral subject positioning and custom ROIs to assess upper leg total, fat, and lean masses are accurate and reliable compared with total-body frontal subject positioning. Future studies are needed to determine the clinical usefulness of lateral view measures regarding prevention or rehabilitation of sports- or age-related injury. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare whole and segmental body composition and bone mineral density of collegiate American football players by playing positions. Forty collegiate American football players voluntarily participated in this study. Participants were categorized by playing positions into one of five categories i.e., defensive linemen, offensive linemen, defensive secondary players, offensive secondary players and receivers. Whole body composition and bone mineral density were measured by dual x-ray absorptiometry. Offensive and defensive linemen had higher body mass, a body mass index, lean mass and a fat mass index compared to the remaining three positions and a higher lean mass index compared to offensive secondary players and receivers. Offensive linemen had a higher body fat percentage and lower values of upper to lower lean mass than offensive and defensive secondary players and receivers, and higher total mass to the lean mass ratio and fat mass to the lean mass ratio compared to the other players. Offensive linemen had a higher fat mass index and fat mass to the lean mass ratio than defensive linemen. However, in all other measures they were similar. Offensive and defensive secondary players and receivers were similar with respect to the measured variables. Bone mineral density of the players was within the normal range and no difference in lean mass was observed between the legs. In conclusion, findings of this study showed that the total and segmental body composition profile of collegiate American football players reflected the demands of particular playing positions. [ABSTRACT FROM AUTHOR]

Prenatal alcohol exposure can contribute to long term adverse health outcomes. Development of the skeletal system begins at the early embryonic stage and continues into early adulthood but the effect of prenatal alcohol exposure on skeletal growth is relatively unexplored in a clinical population. Here, we performed dual X-ray absorptiometry to examine bone, fat, and muscle accrual in children and adolescents diagnosed with, or at risk of, fetal alcohol spectrum disorders (FASDs). Children (aged 4–9 years) with FASD or at risk of FASD (n = 10) had similar growth to age matched controls (n = 27). By adolescence (aged ≥10 years), those with FASDs (n = 13) were shorter and had lower areal bone mineral density and lean tissue mass than typically developing peers (n = 29). Overall, adolescents diagnosed with FASDs had greater odds of impairments to bone and body composition. These findings highlight the importance of early FASD diagnosis and appropriate post-diagnostic medical follow-up to enable timely, effective interventions to optimize bone and body composition during paediatric growth. [Display omitted] • Children with/at risk of FASDs had similar growth to control group. • Adolescents with FASDs had lower bone mineral density than the control group. • Findings highlight importance of early diagnosis of FASDs. [ABSTRACT FROM AUTHOR]

Summary Background & aims The main objectives of weight loss interventions in children and adolescents are to decrease fat mass while maintaining fat-free mass. Several methods are available to assess childhood and adolescence obesity, such as weight and height, bioelectrical impedance, skin-fold thickness measurements and other laboratory methods. The aim was to assess simple anthropometric indices as predictors of body-fat changes, using dual-energy X-ray absorptiometry measurements as reference method. Methods Multi-intervention approach (diet, physical activity and psychological support in a family-group-based treatment) was implemented with a one-year follow-up in 13-to-16-year-old overweight or obese Spanish adolescents. A total of 83 adolescents were recruited from Granada and Zaragoza, males ( n = 43) (31.6 kg/m 2 ) and females ( n = 40) (32.0 kg/m 2 ). We measured body composition with anthropometry and dual-energy X-ray absorptiometry. All measurements were made at baseline, and after 2 and 13 months. Random coefficient regression model was used to calculate the proportion of body composition changes during follow-up that would be explained by simple body composition indices based on anthropometric measures. Results After controlling for age and Tanner stage, body mass index explained 76.5% of body composition changes in males and 90.1% in females, while fat mass index (assessed by skin-folds) explained 78.9% of body composition changes in males and 84.0% of body composition changes in females. Conclusions In conclusion, we found that BMI was a good indicator of body fat composition changes in children and adolescents, although FMI assessed by anthropometry was also a good indicator. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to investigate muscle size, quality and body composition characteristics in Division I cross country runners with a history of stress fractures and without. Researchers evaluated 21 male and 15 female subjects. They found that male and female runners with a history of fractures were not different in any studied variables compared to runners with no fracture history and that more muscle mass is associated with higher bone mineral density and bone mineral content.