Body Dual-energy X-ray Absorptiometry Research Articles

Association Between DXA And HR-pQCT Measurements Of BMD In Active, Recruit-aged Men And Women

Dual-energy X-ray absorptiometry (DXA) areal bone mineral density (aBMD) measurements are routinely employed to assess fracture risk despite the limitations of a two-dimensional, estimated projection of bone volume. Conversely, high-resolution peripheral quantitative computed tomography (HR-pQCT) provides three-dimensional volumetric BMD (vBMD) measurements of total, trabecular, and cortical bone, offering better characterization of fracture risk. It remains unclear whether regional aBMD accurately reflects vBMD of specific bone compartments in the distal tibia, a common injury site for military personnel. PURPOSE: To determine if lower limb aBMD correlates with distal total (Tt), trabecular (Tb) and cortical (Ct) vBMD in healthy, recruit-aged men and women. METHODS: Seventy-six recreationally active men (n = 43;26.4 ± 0.8 yrs.), and women (n = 33;26.2 ± 4.7 yrs.), free of any musculoskeletal conditions that could influence BMD, completed two HR-pQCT (XtremeCT; Scanco Medical) and one total body DXA (Lunar iDXA; GE Healthcare) scans. Total body DXA and non-dominant tibial HR-pQCT scans at the metaphysis (4% site) and diaphysis (30% site) were obtained. Lower leg aBMD was assessed in DXA scans with custom region of interest (ROI) analysis between the ultradistal tibia and the tibial plateau. Associations between variables were analyzed with Pearson’s correlation coefficient (r2); alpha was set at p < 0.05. RESULTS: aBMD positively correlated with Tt vBMD at the 4% site for men (r2 = 0.42; p < 0.001) and women (r2 = 0.17; p = 0.016) but only in men at the 30% site (r2 = 0.16; p = 0.008). aBMD positively correlated with Tb vBMD at the 4% site for men (r2 = 0.35; p < 0.001) and women (r2 = 0.20; p = 0.010), but not at the 30% site for either sex. aBMD was not correlated with Ct vBMD at the 4% site for either sex but was positively correlated with Ct vBMD at the 30% site in men (r2 = 0.12; p = 0.032). CONCLUSIONS: There is poor to moderate association between lower limb aBMD and tibial vBMD at both sites, with greater association in men than in women. aBMD is unlikely to provide a suitable assessment of distal tibial bone health. aBMD and tibial vBMD should, therefore, not be used interchangeably to examine the bone response to interventions or for the prediction of fracture risk. Supported by UK Ministry of Defence (WGCC 5.5.6-Task 0107).

Measured Versus Estimated Resting Metabolic Rate in Heart Failure With Preserved Ejection Fraction.

Obesity is common in heart failure with preserved ejection fraction (HFpEF), and a hypocaloric diet can improve functional capacity. Malnutrition, sarcopenia, and frailty are also frequently present, and calorie restriction could harm some patients. Resting metabolic rate (RMR) is an essential determinant of caloric needs; however, it is rarely measured in clinical practice. The accuracy of commonly used predictive equations in HFpEF is unknown. RMR was measured with indirect calorimetry in 43 patients with HFpEF undergoing right heart catheterization at the University of Michigan, and among 49 participants in the SECRET trial (Study of the Effects of Caloric Restriction and Exercise Training in Patients With Heart Failure and a Normal Ejection Fraction); SECRET patients also had dual-energy X-ray absorptiometry body composition measures. Measured RMR was compared with RMR estimated using the Harris Benedict, Mifflin-St Jeor, World Health Organization, and Academy for Nutrition and Dietetics equations. All predictive equations overestimated RMR (by >10%, P<0.001 for all), with mean (95% CI) differences Harris Benedict equation +250 (186-313), Mifflin-St. Jeor equation +169 (110-229), World Health Organization equation +300 (239-361), and Academy for Nutrition and Dietetics equation +794 (890-697) kcal/day. Results were similar across both patient groups, and the discrepancy between measured and estimated RMR tended to increase with body mass index. In SECRET, measured RMR was closely associated with lean body mass (ρ=0.74; by linear regression adjusted for age and sex: β=27 [95% CI, 18-36] kcal/day per kg, P<0.001; r2=0.56). Commonly used predictive equations systematically overestimate measured RMR in patients with HFpEF. Direct measurement of RMR may be needed to effectively tailor dietary guidance in this population. Registration: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT00959660.

MRI Based Validation of Abdominal Adipose Tissue Measurements From DXA in Postmenopausal Women

Visceral adipose tissue (VAT) is a hypothesized driver of chronic disease. Dual-energy X-ray absorptiometry (DXA) potentially offers a lower cost and more available alternative compared to gold-standard magnetic resonance imaging (MRI) for quantification of abdominal fat sub-compartments, VAT and subcutaneous adipose tissue (SAT). We sought to validate VAT and SAT area (cm2) from historical DXA scans against MRI. Participants (n = 69) from the Women's Health Initiative (WHI) completed a 3 T MRI scan and a whole body DXA scan (Hologic QDR2000 or QDR4500; 2004-2005). A subset of 43 participants were scanned on both DXA devices. DXA-derived VAT and SAT at the 4th lumbar vertebrae (5 cm wide) were analyzed using APEX software (v4.0, Hologic, Inc., Marlborough, MA). MRI VAT and SAT areas for the corresponding DXA region of interest were quantified using sliceOmatic software (v5.0, Tomovision, Magog, Canada). Pearson correlations between MRI and DXA-derived VAT and SAT were computed, and a Bland-Altman analysis was performed. Participants were primarily non-Hispanic white (86%) with a mean age of 70.51 ± 5.79 years and a mean BMI of 27.33 ± 5.40 kg/m2. Correlations between MRI and DXA measured VAT and SAT were 0.90 and 0.92, respectively (p ≤ 0.001). Bland-Altman plots showed that DXA-VAT slightly overestimated VAT on the QDR4500 (-3.31 cm2); this bias was greater in the smaller subset measured on the older DXA model (QDR2000; -30.71 cm2). The overestimation of DXA-SAT was large (-85.16 to -118.66 cm2), but differences were relatively uniform for the QDR4500. New software applied to historic Hologic DXA scans provide estimates of VAT and SAT that are well-correlated with criterion MRI among postmenopausal women.

Association of X-ray Absorptiometry Body Composition Measurements with Basic Anthropometrics and Mortality Hazard.

Dual-energy X-ray absorptiometry (DEXA) is a non-invasive imaging modality that can estimate whole-body and regional composition in terms of fat, lean, and bone mass. We examined the ability of DEXA body composition measures (whole-body, trunk, and limb fat mass and fat-free mass) to predict mortality in conjunction with basic body measures (anthropometrics), expressed using body mass index (BMI) and a body shape index (ABSI). We used data from the 1999–2006 United States National Health and Nutrition Examination Survey (NHANES), with mortality follow-up to 2015. We found that all DEXA-measured masses were highly correlated with each other and with ABSI and that adjustment for BMI and ABSI reduced these dependencies. Whole-body composition did not substantially improve mortality prediction compared to basic anthropometrics alone, but regional composition did, with high trunk fat-free mass and low limb fat-free mass both associated with elevated mortality risk. These findings illustrate how DEXA body composition could guide health assessment in conjunction with the more widely employed simple anthropometrics.

Abdominal Adiposity in Collegiate Football Linemen: A Study of Race and Position.

American football linemen are at an increased risk for developing obesity-related diseases. This study evaluated the impact of race and position on abdominal fat (visceral adipose tissue and android fat percentage) in football linemen. Thirty-four offensive and defensive linemen (%fat: 27.1±7.2%) completed a total body dual-energy X-ray absorptiometry scan to estimate visceral fat and android fat percentage. Participants were stratified by race [Black: n=23; White: n=11] and position (Offense: n=18; Defense: n=16). Two separate two-way ANOVA tests [race × position] were completed. For visceral adipose tissue, there was no interaction (p=0.056), but there was an effect of race (Black: 0.57±0.34 kg; White: 1.51±0.56 kg; p <0.001) and position (Offense: 1.22±0.60 kg; Defense: 0.49±0.34 kg; p<0.001). For android fat percentage, there was no interaction (p=0.855) or race effect (Black: 31.5±11.3%; White: 40.9±8.6%; p=0.123); there was a position effect (Offense: 42.1±5.6%; Defense: 26.0±9.9%; p<0.001). Offensive linemen, regardless of race, had greater visceral adipose tissue and android fat percent compared to defensive linemen. White linemen had greater visceral adipose tissue, regardless of position. These results suggest football linemen, especially offensive linemen with increased abdominal adiposity, may benefit from tracking metabolic health during their collegiate career to mitigate obesity-related disease risk once retired from sport.

A comparison of non-invasive methods of measuring body composition in patients with heart failure: a report from SICA-HF.

BackgroundCachexia is common in patients with chronic heart failure and is associated with poor prognosis. How best to measure body composition is not clear.Methods and resultsWe characterized body composition in 120 patients with chronic heart failure: mean (SD) age 70 (10) years, left ventricular ejection fraction 44 (10) %, and median (Q1–Q3) N‐terminal pro B‐type natriuretic peptide 845 (355–1368) ng/L. We measured body composition using dual‐energy X‐ray absorptiometry (DEXA) and a multi‐frequency bioelectrical impedance analysis (BIA) device (Tanita BIA MC‐180MA). Mean (SD) fat mass (FM) was 27.2 (11.7) kg by BIA and 32.3 (12.2) kg by DEXA (mean difference −5.1 kg, 95% limits of agreement: −11.7, 1.5; 4% of values outside limit of agreement); mean (SD) lean mass (LM) was 56.6 (10.9) kg by BIA and 51.1 (9.9) kg by DEXA (mean difference 5.5 kg, 95% limits of agreement: −1.3, 12.3; 6% of values outside limit of agreement); and mean (SD) bone mass (BM) was 3.0 (0.5) kg by BIA and 2.8 (0.6) kg by DEXA (mean difference 0.2 kg, 95% limits of agreement: −0.5, 0.8; 5% of values outside limit of agreement). There was a close correlation between DEXA and BIA for both LM and FM (LM: r = 0.95, P < 0.001; FM: r = 0.96, P < 0.001) but less so for BM (r = 0.84, P < 0.001). Both DEXA and BIA body composition measurements correlated well with other measures of body size (body mass index, hip circumference, and waist circumference).ConclusionsThere are differences in the measurements of FM, LM, and BM between the two techniques, which should not be used interchangeably.

Comparison of Indirect Calorimetry and Common Prediction Equations for Evaluating Changes in Resting Metabolic Rate Induced by Resistance Training and a Hypercaloric Diet.

Rodriguez, C, Harty, PS, Stratton, MT, Siedler, MR, Smith, RW, Johnson, BA, Dellinger, JR, Williams, AD, White, SJ, Benavides, ML, and Tinsley, GM. Comparison of indirect calorimetry and common prediction equations for evaluating changes in resting metabolic rate induced by resistance training and a hypercaloric diet. J Strength Cond Res 36(11): 3093-3104, 2022-The ability to accurately identify resting metabolic rate (RMR) changes over time allows practitioners to prescribe appropriate adjustments to nutritional intake. However, there is a lack of data concerning the longitudinal utility of commonly used RMR prediction equations. The purpose of this study was to evaluate the validity of several commonly used prediction equations to track RMR changes during a hypercaloric nutritional intervention and supervised resistance exercise training program. Twenty resistance-trained men completed the study. The protocol lasted 6 weeks, and subjects underwent RMR assessments by indirect calorimetry (IC) preintervention and postintervention to obtain reference values. Existing RMR prediction equations based on body mass (BM) or dual-energy X-ray absorptiometry fat-free mass (FFM) were also evaluated. Equivalence testing was used to evaluate whether each prediction equation demonstrated equivalence with IC. Null hypothesis significance testing was also performed, and Bland-Altman analysis was used alongside linear regression to assess the degree of proportional bias. Body mass and FFM increased by 3.6 ± 1.7 kg and 2.4 ± 1.6 kg, respectively. Indirect calorimetry RMR increased by 165 ± 97 kcal·d -1 , and RMR:FFM increased by 5.6 ± 5.2%. All prediction equations underestimated mean RMR changes relative to IC, with magnitudes ranging from 75 to 155 kcal·d -1 , while also displaying unacceptable levels of negative proportional bias. In addition, no equation demonstrated equivalence with IC. Common RMR prediction equations based on BM or FFM did not fully detect the increase in RMR observed with resistance training plus a hypercaloric diet. Overall, the evaluated prediction equations are unsuitable for estimating RMR changes in the context of this study.

Interleukin (IL)-10 Is Important in the Maintenance of Trabecular and Cortical Bone and Protects Against Western Diet-Induced Disruption in Bone Remodeling in Mice

ObjectivesThe purpose of this study was to investigate if consumption of a western diet (WD) exacerbates the effects of loss of function of IL-10, an anti-inflammatory cytokine, on biomarkers of bone metabolism and microarchitecture. MethodsSix-week-old male B6.129P2-Il10tm1Cgn/J (IL-10 KO) and C57BL/6 mice (WT) were randomized to treatment in a 2 × 2 factorial with diet (AIN-93 control diet CD vs WD) and strain (IL-10 KO vs WT) as factors. Due to potential influence of high fat on intestinal Ca absorption, a WD diet with added Ca (1.2 g/kg) was used. After 12 wks, whole body dual-energy x-ray absorptiometry scans were performed to assess bone density and body composition, and micro-computed x-ray tomography was used to evaluate trabecular and cortical bone microarchitecture in the femur and lumbar vertebra. Serum biomarkers of bone formation, procollagen 1 intact N-terminal propeptide (P1NP), and resorption, c-terminal telopeptide of type I collagen (CTX-1) were assessed. ResultsBody weight, but not % body fat, was lower (P < 0.05) in IL-10 KO mice relative to WT controls. 12 weeks of WD increased (P < 0.05) body weight and % fat, but the response was not as great in the IL-10 KO mice. Bone mineral density and content were lower in IL-10 KO mice compared to WT, and the WD had no effect on these parameters. The IL-10 KO mice exhibited a decrease in trabecular bone volume, thickness, and number, and an increase in trabecular separation and structure model index compared to WT mice within the femur and vertebrae. The WD had no effect on these trabecular bone parameters. Cortical bone thickness and area were reduced (P < 0.05) and porosity increased in both the femur and vertebra of IL-10 KO mice relative to their WT counterparts. This strain effect was not altered by the WD. IL-10 KO mice exhibited a significantly lower serum PINP and higher CTX-1 compared to the WT mice. Despite the lack of structural changes in bone after 12 wks, the WD increased (P < 0.05) CTX-1 and tended to suppress P1NP (P = 0.051) in the IL-10 KO mice compared to WT. ConclusionsWe conclude that IL-10 plays an important role in bone metabolism and maintaining structural properties and in the absence of IL-10, WD negatively affects both osteoclast and osteoblast activity. Further studies are warranted to determine if structural changes occur with longer exposure to WD. Funding SourcesOklahoma Agricultural Experiment Station.

Objectively Measured Physical Activity Is Associated With Body Composition and Metabolic Profiles of Pacific and New Zealand European Women With Different Metabolic Disease Risks.

Objective: To assess associations between physical activity (PA), body composition, and biomarkers of metabolic health in Pacific and New Zealand European (NZE) women who are known to have different metabolic disease risks.Methods: Pacific (n = 142) or NZE (n = 162) women aged 18–45 years with a self-reported body mass index (BMI) of either 18.5–25.0 kg⋅m–2 or ≥30.0 kg⋅m–2 were recruited and subsequently stratified as either low (<35%) or high (≥35%) BF%, with approximately half of each group in either category. Seven-day accelerometery was used to assess PA levels. Fasting blood was analysed for biomarkers of metabolic health, and whole body dual-energy X-ray absorptiometry (DXA) was used to estimate body composition.Results: Mean moderate-to-vigorous physical activity (MVPA; min⋅day–1) levels differed between BF% (p < 0.05) and ethnic (p < 0.05) groups: Pacific high- 19.1 (SD 15.2) and low-BF% 26.3 (SD 15.6) and NZE high- 30.5 (SD 19.1) and low-BF% 39.1 (SD 18.4). On average Pacific women in the low-BF% group engaged in significantly less total PA when compared to NZE women in the low-BF% group (133 cpm); no ethnic difference in mean total PA (cpm) between high-BF% groups were observed: Pacific high- 607 (SD 185) and low-BF% 598 (SD 168) and NZE high- 674 (SD 210) and low-BF% 731 (SD 179). Multiple linear regression analysis controlling for age and deprivation showed a significant inverse association between increasing total PA and fasting plasma insulin among Pacific women; every 100 cpm increase in total PA was associated with a 6% lower fasting plasma insulin; no significant association was observed in NZE women. For both Pacific and NZE women, there was an 8% reduction in fasting plasma insulin for every 10-min increase in MVPA (p ≤ 0.05).Conclusion: Increases in total PA and MVPA are associated with lower fasting plasma insulin, thus indicating a reduction in metabolic disease risk. Importantly, compared to NZE, the impact of increased total PA on fasting insulin may be greater in Pacific women. Considering Pacific women are a high metabolic disease risk population, these pre-clinical responses to PA may be important in this population; indicating promotion of PA in Pacific women should remain a priority.

Predicting Cardiometabolic Risk From Visceral Abdominal Adiposity in Persons With Chronic Spinal Cord Injury

Persons with spinal cord injury (SCI) have increased adiposity that may predispose to cardiovascular disease compared to those who are able-bodied (AB). The purpose of this study was to determine the relationships between dual energy X-ray absorptiometry (DXA)-derived visceral adipose tissue (VAT) and biomarkers of lipid metabolism and insulin resistance in persons with chronic SCI. A prospective observational study in participants with chronic SCI and age- and gender-matched AB controls. The study was conducted at a Department of Veterans Affairs Medical Center and Private Rehabilitation Hospital. The quantification of DXA-derived VAT volume (VATvol) and blood-derived markers of lipid and carbohydrate metabolism were determined in 100 SCI and 51 AB men. The VATvol was acquired from a total body DXA scan and analyzed using iDXA enCore CoreScan software (GE Lunar). Blood samples were collected for the serum lipid profile and plasma and glucose concentrations, with the latter two values used to calculate a measure of insulin resistance. In the SCI and AB groups, VAT% was significantly correlated with most cardiometabolic biomarkers. The results of the binary logistic regression analysis revealed that participants who had a VATvol above the cutoff value of 1630 cm3 were 3.1-, 4.8-, 5.6-, 19.2-, and 16.7-times more likely to have high serum triglycerides (R2N= 0.09, p = 0.014), low serum high density lipoprotein cholesterol (R2N = 0.16, p < 0.001), HOMA2-IR (R2N = 0.18, p < 0.001), metabolic syndrome (R2N = 0.25, p < 0.001), and a 10-yr Framingham Risk Score ≥ 10% (R2N = 0.16, p = 0.001), respectively, when compared to participants below this VATvol cutoff value. Our findings reveal that persons with chronic SCI have a higher VATvol than that of AB controls, and VATvol correlates directly with biomarkers of lipid and carbohydrate metabolism that are strong predictors of cardiometabolic disorders.

Accuracy and reliability of the InBody 270 multi-frequency body composition analyser in 10-12-year-old children.

The aim of this study was at examining the validity and reliability of a marketed bioimpedance (BIA) scale for body composition assessment, in children engaged in an educational football project (FIFA 11 for Health). One-hundred and twenty-seven children (70 boys and 57 girls; age 10.7±0.5 years, body mass 41.2±9.0 kg, Body mass index 18.5±3.3 kg·m-2 and stature 149±7 cm) were evaluated for total body mass, lean body mass, muscle mass, using BIA (InBody 270, Biospace, California, USA) and dual-energy X-ray absorptiometry (DEXA, Lunar Prodigy, GE Medical Systems, Madison, Wisconsin, USA), at baseline conditions. Data analyses were carried out separately for girls and boys. Nearly perfect associations (r = 0.97−0.99) and excellent absolute (TEM = 0.04−1.9%) and relative (ICC = 0.98−1.00) inter-device reliability were found between DEXA and BIA variables. Fat and lean body mass bias (p < .0001) were practically relevant both for the boys (2.56 and 11.22 kg, respectively) and the girls (2.33 and 10.49 kg, respectively). Muscle mass and body fat were underestimated and overestimated, respectively, for the boys and girls. InBody 270 is a valid BIA system for estimating body composition with an excellent inter-device relative and absolute reliability. However, the remarkable measurements bias of BIA fat and muscle mass values discourage its use for clinical prescription. The BIA body composition biases were sex dependent.

Effect of metformin and insulin vs. placebo and insulin on whole body composition in overweight patients with type 2 diabetes: a randomized placebo-controlled trial.

Glucose-lowering medications affect body composition. We assessed the long-term effects of metformin compared with placebo on whole body bone and body composition measures in patients with type 2 diabetes mellitus. This was a sub-study of the Copenhagen Insulin and Metformin Therapy trial, which was a double-blinded randomized placebo-controlled trial assessing 18-month treatment with metformin compared with placebo, in combination with different insulin regimens in patients with type 2 diabetes mellitus (T2DM). The sub-study evaluates the effects on bone mineral content (BMC), density (BMD), and body composition from whole body dual-energy X-ray absorptiometry (DXA) scans which were assessed at baseline and after 18 months. Metformin had a small, but positive, (p < 0.05) effect on subtotal, appendicular, and legs BMC and BMD compared with placebo. After adjustment for sex, age, vitamin D, smoking, BMI, T2DM duration, HbA1c, and insulin dose, the effects on appendicular BMC and BMD persisted (p < 0.05 for both). The changes in appendicular BMC and BMD corresponded approximately to a 0.7% and 0.5% increase in the metformin group and 0.4% and 0.4% decrease in the placebo group, respectively. These effects were mostly driven by an increase in BMC and BMD in the legs and a loss of BMC and BMD in the arms. During 18 months, all participants increased in weight, fat mass (FM), FM%, and lean mass (LM), but decreased in LM%. The metformin group increased less in weight (subtotal weight (weight-head) - 2.4 [- 3.5, - 1.4] kg, p value < 0.001) and FM (- 1.5 [- 2.3, - 0.8] kg, p value < 0.001) and decreased less in LM% (0.6 [0.2, 1.1] %, p value < 0.001) compared with the placebo group. Metformin treatment had a small positive effect on BMC and BMD in the peripheral skeleton and reduced weight gain compared with placebo in insulin-treated patients with T2DM.

Short-term resistance training in older adults improves muscle quality: A randomized control trial.

The purpose of this study was to evaluate whether dumbbell resistance training (DBRT) and elastic band resistance training (EBRT) are equally beneficial in the older adult. Sixty-five healthy participants (mean±SD; age=66.5±7.09years; height=165.2±10.6cm; body mass=74.5±14.6kg) volunteered for this study. Participants underwent a total body dual-energy x-ray absorptiometry (DXA) scan for segmental and total body muscle and fat estimation. Functional tests included the short physical performance battery, timed up-and-go, and heel-to-toe walk. Strength was measured on dominant handgrip strength, maximal bench press, and leg press. Participants were block randomized into one of three groups: elastic band resistance training (EBRT), dumbbell resistance training (DBRT), or control (CON). EBRT and DBRT were asked to visit the laboratory twice weekly over 6-weeks while CON maintained their daily routine. Data were analyzed using a two-way repeated measures ANOVA and an alpha set at 0.05. Results indicated there was a two-way interaction for bench press, leg press, upper- and lower-body muscle quality and total arm lean mass (p<0.05). Specifically, the EBRT and DBRT improved from pre to post for total arm lean mass (p<0.021, p<0.004, respectively). Additionally, for bench press and leg press, all groups improved pre to post training (p<0.05) with DBRT superior to CON. These data suggest that EBRT provides an effective, portable, and cost-effective means to enhance lower-body function and muscle quality in an aging population, yet DBRT may be more impactful for total-body improvements.

Evaluation of Obesity Cutoff Values in Hispanic Adults: Derivation of New Standards

The diagnostic accuracy of clinical-based body composition methods such as body mass index (BMI), waist circumference (WC), bioimpedance analysis (BIA), and dual energy X-ray absorptiometry (DXA) has yet to be evaluated in Hispanic adults. Moreover, it has also been suggested that previously established obesity cutoff values may need adjusting. Purpose: The primary aim of this study was to investigate the diagnostic accuracy of BMI, WC, BIA, and DXA for obesity classification in Hispanic adults. The secondary aim was to internally derive obesity cutoff values producing equal sensitivity and specificity for the respective tests. Methods: Hispanic females (n = 101) and males (n = 90) volunteered to participate in this study (18–45 years). Body fat percentage was estimated with BIA, DXA, and a 4-compartment (4C) model. Obesity-defined criteria was employed as follows: (Body fat percentage ≥ 25% and 35% and WC ≥ 102cm and 88cm for males and females, respectively; BMI ≥ 30 kg/m2). A 4C model was used as a criterion to evaluate BMI, WC, DXA, and BIA. Results: Sensitivity of DXA and BIA (74.1%–96.9%) was greater than BMI and WC (25.8%–51.9%) when using previously established standards. However, specificity was poor for DXA (<70%), but considered good to excellent for BMI, WC, and BIA (83.1%–96.6%) when using previously established standards. Internally derived cutoff values improved sensitivity for BMI and WC (74.2%–81.5%) and improved specificity for DXA (>80.0%). Conclusion: The internally derived cutoff values, producing identical sensitivity, and specificity, were developed and shown to improve the diagnostic performance of the body composition methods compared to previously established obesity cutoff standards. Consequently, the internally derived obesity cutoff values are recommended for use by allied health professionals in clinical practice when equal sensitivity and specificity is desired.

Evaluation of the body adiposity index against dual-energy X-ray absorptiometry for assessing body composition in children and adolescents.

It is important to clarify the association of lean and fat mass between children and adolescents considering the rising prevalence of overweight and obesity in this age group. The aim of this study was to verify the association between the body adiposity index (BAI) and dual-energy X-ray absorptiometry (DXA) methods for analyzing body composition, as well as analyzing the validity of BAI to verify the percentage of fat in children and adolescents. The sample was composed of 106 children and adolescents, 44 females (age: 11.5± 1.8 years) and 62 evils (13.6± 2.6 years). The body fat (%F) was measured using DXA and the doubly indirect BAI body fat estimation technique. The BAI and DXA estimates of %F were strongly correlated (boys: r=.71, P<.0001; girls: r=.72, P<.0001). The linear regression analyses showed that BAI is significant to estimate the %F in total sample (P<.0001). For boys, the %F analyzes performed by BAI and DXA did not show any differences when compared (P=.2). In addition, BAI pointed out a significant proportion bias for both sexes (P<.0001), which suggests its inefficiency in the analysis of %F. BAI and DXA correlate; however, there is low reliability and a high proportion bias for the analysis of %F by BAI.

Multicomponent Exercise Training Combined with Nutritional Counselling Improves Physical Function, Biochemical and Anthropometric Profiles in Obese Children: A Pilot Study.

Aerobics or strength exercise plus diet interventions have been shown to counteract childhood obesity. However, little is known with regard to periodized multicomponent exercise interventions combined with nutritional counselling, which might be less demanding but more enjoyable and respectful of children and adolescents’ nature. In order to analyze the impact of such a multimodal approach, 18 obese children (10.8 ± 1.6 years; 63% females; z Body Mass Index 3 ± 0.4) trained for 60 min, twice weekly and were measured for body composition, biochemical parameters and physical function. We found that 16 weeks of multimodal intervention (14 of training), based on fun-type skill-learning physical activities and physical conditioning with challenging circuits and games, together with nutritional counselling, led to an attendance > 80%, with significant overall health improvement. Body composition was enhanced (p < 0.01 for z BMI, mid-upper-arm-circumference, waist-to-height ratio, tricipital and subscapular skinfolds, body-fat % by Slaughter equation and Dual energy X-ray absorptiometry body fat% and trunk fat%), as well as metabolic profile (LDL cholesterol, gamma-glutamyl transferase , alanine aminotransferase ; p < 0.05), homeostatic model assessment of insulin resistance (HOMA-IR; p < 0.05) and inflammatory response (C-Reactive Protein; p < 0.05). Physical fitness was also improved (p < 0.01) through better cardiovascular test scores and fundamental movement patterns (Functional Movement Screen-7, FMS-4). Tailoring multimodal supervised strategies ensured attendance, active participation and enjoyment, compensating for the lack of strict caloric restrictions and the low volume and training frequency compared to the exercise prescription guidelines for obesity. Nutritional counselling reinforced exercise benefits and turned the intervention into a powerful educational strategy. Teamwork and professionals’ specificity may also be key factors.

Reference centiles for evaluating total body fat development and fat distribution by dual-energy x-ray absorptiometry among children and adolescents aged 3–18 years

The rise in the prevalence of childhood obesity has increased the demand for accurately evaluating body fatness in pediatric population. The aim of this study was to provide a series of sex- and age-specific body fat reference centiles for evaluating total body fat development and fat distribution in Chinese children and adolescents using dual-energy x-ray absorptiometry (DXA). A nationwide sample of Chinese children and adolescents aged 3-18 years (n=12,790) was drawn from a cross-sectional survey of the China Child and Adolescent Cardiovascular Health study (2013-2019). Fat measurements, including total fat mass index (FMI), total body fat percentage (BF%), regional FMI, trunk to leg (T/L) fat ratio and android to gynoid (A/G) fat ratio, were derived from whole body DXA scans. Sex- and age-specific centiles were estimated using the lambda-mu-sigma method and then compared with values derived from the US National Health and Nutrition Examination Survey (1999-2004) and Korean National Health and Nutrition Examination Survey (2008-2011). During early childhood, almost all body fat parameters decreased with age, except an increase in A/G ratio. After 7 years onward, drastic upward trends of total FMI and BF% were exhibited in boys till 10 years, followed by opposite downward trends during 11-14 years; while sustained increase of FMI was shown in girls across ages accompanied by relatively constant BF% levels. Meanwhile, steady increases were noticed for A/G ratio and T/L ratio, which were more pronounced in boys. In addition, the proposed body fat references were much lower than the US but similar to Koreans despite of subtle differences. This is the first study to present a set of DXA-based body fat reference for Chinese children and adolescents aged 3-18 years. The new reference provides clinicians and researchers a useful tool for assessing body fat development and distribution patterns throughout early childhood and adolescence.

Body composition with dual energy X-ray absorptiometry: from basics to new tools.

Dual-energy X-ray absorptiometry (DXA) in nowadays considered one of the most versatile imaging techniques for the evaluation of metabolic bone disorders such as osteoporosis, sarcopenia and obesity. The advantages of DXA over other imaging techniques are the very low radiation dose, its accuracy and simplicity of use. In addition, fat mass (FM) and lean mass (LM) values by DXA shows very good accuracy compared to that of computed tomography and magnetic resonance imaging. In this review we will explain the technical working principles of body composition with DXA, together with the possible limitations and pitfalls that should be avoided in daily routine to produce high-quality DXA examinations. We will also cover the current clinical practical application of whole body DXA values, with particular emphasis on the use of LM indices in the diagnostic workup of reduced muscle mass, sarcopenia and osteosarcopenic obesity according to the most recent guidelines. The possible use of adipose indices will be considered, such as the fat mass index (FMI) or the android/gynoid ratio, as well as lipodystrophy indices and the evaluation of visceral adipose tissue (VAT). Whenever available, we will provide possible cut-off diagnostic values for each of these LM and FM indices, according to current literature and guidelines.

Head, Neck, Trunk, and Pelvis Tissue Mass Predictions for Older Adults using Anthropometric Measures and Dual-Energy X-Ray Absorptiometry

Background: Regression equations using anthropometric measurements to predict soft (fat mass [FM], lean mass [LM], wobbling mass [WM]) and rigid (bone mineral content [BMC]) tissue masses of the extremities and core body segments have been developed for younger adults (16-35 years), but not older adults (36-65 years). Tissue mass estimates such as these would facilitate biomechanical modeling and analyses of older adults following fall or collision-related impacts that might occur during sport and recreational activities. Purpose: The purpose of this study was to expand on the previously established tissue mass prediction equations of the head, neck, trunk, and pelvis for healthy, younger adults by generating a comparable set of equations for an older adult population. Methods: A generation sample (38 males, 38 females) was used to create head, neck, trunk, and pelvis tissue mass prediction equations via multiple linear stepwise regression. A validation sample (13 males, 12 females) was used to assess equation accuracy; actual tissue masses were acquired from manually segmented full body Dual-Energy X-ray Absorptiometry scans. Results: Adjusted R2 values for the prediction equations ranged from 0.326 to 0.949, where BMC equations showed the lowest explained variances overall. Mean relative errors between actual and predicted masses ranged from –2.6% to 6.1% for trunk LM and FM, respectively. All actual tissue masses except head BMC (R2 = 0.092) were significantly correlated to those predicted from the equations (R2 = 0.403 to 0.963). Conclusion: This research provides a simple and effective method for predicting head, neck, trunk, and pelvis tissue masses in older adults that can be incorporated into biomechanical models for analyzing sport and recreational activities. Future work with this population should aim to improve core segment BMC predictions and develop equations for the extremities.

Associations of truncal body composition with cognitive status in patients with dementia.

Central obesity in midlife is a risk factor of cognitive decline and dementia, and also one of the factors that make cognitive functions deteriorate rapidly. The objective of this study is to investigate the relationship between truncal body composition (fat and muscle) and cognitive impairment in patients with dementia. A total of 81 female over 60years of age with probable Alzheimer's disease were recruited between November 2014 and September 2015. The Mini-Mental State Examination, Global Deterioration Scale, and Clinical Dementia Rating Scale were used to assess the cognitive functions. Both truncal fat and muscle mass were measured using body dual-energy X-ray absorptiometry and used as a percentage of body weight (TMM% and TFM%). Correlations between truncal composition and cognitive status were assessed by simple correlation analysis, which was followed by partial correlation analysis with age and educational years. TFM% was not related to cognitive impairment. In contrast, TMM% had a significantly negative correlation with all three cognitive assessment scores. After further adjusting for age, educational years, and vascular factors, there was still a relationship between TMM% and cognitive functions. Unlike truncal fat mass that showed no relevance with cognitive functions, the truncal muscle mass was negatively correlated with cognitive status. The truncal muscle mass is thought to affect cognitive status in dementia patients somehow.