Assessing Body Composition of Children and Adolescents Using Dual-Energy X-Ray Absorptiometry,Skinfolds, and Electrical Impedance

To determine the validity and reliability of percent body fat estimates in 177 boys and 154 girls between 12–17 years of age, percent body fat was assessed once using dual-energy X-ray absorptiometry and twice using the sum of two skinfolds and three bioelectrical impedance analysis devices. The assessments were repeated on 79 participants on a second day. The agreement between the percent body fat estimates from the four prediction methods and dual-energy X-ray absorptiometry was evaluated using Bland–Altman analyses and a mixed linear model. All methods were reliable within and between days. The sum of two skinfolds (±6.8% body fat), OMRON (OMRON Healthcare Inc., Vernon Hills, Illinois, USA) bioelectrical impedance analysis (0 ± 7.3% body fat), and TANITA 521 (TANITA Corporation, Tokyo, Japan) bioelectrical impedance analysis (±7.6% body fat) had wide prediction intervals and are acceptable for use in large population-based studies. The TANITA 300A bioelectrical impedance analysis is not recommended for use in children and adolescents due to its wide prediction interval (±8.1% body fat) and large bias. A criterion method should be used when the accurate assessment of body composition of an individual is critical.     

Body Composition Comparison: Bioelectric Impedance Analysis with Dual-Energy X-Ray Absorptiometry in Adult Athletes

The primary purpose of this study was to investigate the accuracy of the DF50 (ImpediMed Ltd, Eight Mile Plains, Queensland, Australia) bioelectrical impedance analysis device using dual-energy x-ray absorptiometry as the criterion in two groups: endurance athletes and power athletes. The secondary purpose was to develop accurate body fat percentage prediction equations for each group based on bioelectrical impedance analysis data and/or the combination of bioelectrical impedance analysis and anthropometric data.

Eighty male athletes (40 elite endurance athletes and 40 were power athletes), age 19–48 with body mass indexes ranging from 18.9 to 37.4 were recruited. Anthropometric measurements were taken. Body composition was assessed by dual-energy x-ray absorptiometry and bioelectrical impedance analysis. An athlete-specific bioelectrical impedance analysis prediction equation was developed by stepwise regression analysis using dual-energy x-ray absorptiometry as the criterion and bioelectrical impedance analysis data and anthropometric measurements as predictor variables.

The DF50 bioelectrical impedance analysis significantly overestimated body fat percentage by 6.4 ± 0.5 in the entire group (p < .001) and in both the endurance group (6.1 ± .6, p < .001) and the power group (6.7 ± 0.7, p < .001). The endurance and power group showed no significant difference in the error of estimation by bioelectrical impedance analysis (p = .554), indicating that bioelectrical impedance analysis has the same error in both groups. The final prediction equation incorporated both anthropometric variables as well as bioelectrical impedance analysis variables and produced an adjusted r² of .982 and a standard error of the estimate (SEE) of 1.98 for the entire group. This prediction equation used bioelectrical impedance analysis measurements and anthropometric measurements, specifically trunk measurements, to account for trunk size, a common source of error in bioelectrical impedance analysis equations. Follow-up validation studies are necessary to further validate the equations produced.     

Estimating fat-free mass in elite-level male rowers: a four-compartment model validation of laboratory and field methods

The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers. METHODS: Twenty-three elite-level male rowers (mean± SD; age 24.6 ± 2.2 years; stature: 191.4 ± 7.2 cm; mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM.     

Reliability and agreement between DXA-derived body volumes and their usage in 4-compartment body composition models produced from DXA and BIA values

Two research groups recently produced equations for estimation of body volume from dual-energy x-ray absorptiometry (DXA) scans. These body volume estimates can be used for body composition evaluation in modified 4-compartment models. In the present analysis, the reliability of body volume calculations, as well as their usage in 4-compartment models, was explored while employing precise scheduling of assessments and dietary standardization. Forty-eight recreationally active males and females completed two pairs of identical assessments, which included a DXA scan and single-frequency bioelectrical impedance analysis. Each assessment within a pair was separated by 24 hours, during which participants were provided a standardized diet. Body volume and 4-compartment equations were applied to the data, and metrics of reliability and agreement were calculated for body volume and 4-compartment components. While both body volume equations demonstrated excellent reliability individually, substantial disagreement between equations was present when utilized in 4-compartment equations. The magnitude of this disagreement was 4.3 kg for lean mass and fat mass and 6.9% for body fat percentage. At present, the large discrepancies in body composition components when using existing body volume equations preclude their interchangeability and demonstrate the need for continued exploration of the utility of body volume estimates.     

身体成分测量与评价的理论和方法

身体成分评价是指体内各种成分的含量。常用各种物质的组成和比例表示。一旦机体内部各成分比例失衡。将会严重危险人类的健康。所以,关注身体成分的测量与评价已经成为世界性话题。多年的研究证实,身体成分评价的理论模型多见于“2-成分”模型和“多-成分”模型。现在较为流行的测量和评价方法包括水下称重法,皮褶厚度法、生物电阻抗法和双能量X吸收法等。     

Prediction of fat and fat-free mass in male athletes using dual X-ray absorptiometry as the reference method

The ability of bioelectrical impedance analysis and anthropometry to predict fat mass and fat-free mass was compared in a sample of 82 male athletes from a wide variety of sports, using dual-energy X-ray absorptiometry (DXA) as the reference method. The percent fat measured by DXA was 10.9+/-4.9% (mean +/- s), and fat mass was predicted with a standard error of the estimate of 1.7 kg for skinfolds and 2.8 kg for bioelectrical impedance analysis (P < 0.001). Fat-free mass was predicted with a standard error of the estimate of 1.7 kg for anthropometry and 2.6 kg for bioelectrical impedance analysis (P < 0.001). Regression of various individual skinfolds and summed skinfolds, to examine the effect of skinfold selection combinations by stepwise regression, produced an optimal fat mass prediction using the thigh and abdominal skinfold sites, and an optimal fat-free mass prediction using the thigh, abdominal and supra-ilium sites. These results suggest that anthropometry offers a better way of assessing body composition in athletes than bioelectrical impedance analysis. Applying the derived equations to a separate sample of 24 athletes predicted fat and fat-free mass with a total error of 2.3 kg (2.9%) and 2.2 kg (2.7%), respectively. Combining the samples introduced more heterogeneity into the sample (n = 106), and the optimal prediction of fat mass used six skinfolds in producing a similar standard error of the estimate (1.7 kg), although this explained a further 4% of the variation in DXA-derived fat. Fat-free mass was predicted best from four skinfolds, although the standard error of the estimate and coefficient of determination were unchanged.     

人体骨骼肌含量测定方法综述

骨骼肌是组织-器官层次上最大的身体组分,也是一切体力活动的物质基础。现在已有若干基于性质或基于组分的方法,能够在活体测定身体的骨骼肌含量。计算机体层摄影（CT）与磁共振（MRI）这两种技术可以作为校验新方法的标准。最新发展的基于双能量X-射线吸收技术（DXA）的方法,可以替代CT及MRI,准确地测定活体的全身骨骼肌含量。     

Prediction of fat and fat-free mass in male athletes using dual X-ray absorptiometry as the reference method

The ability of bioelectrical impedance analysis and anthropometry to predict fat mass and fat-free mass was compared in a sample of 82 male athletes from a wide variety of sports, using dual-energy X-ray absorptiometry (DXA) as the reference method. The percent fat measured by DXA was 10.9 - 4.9% (mean - s ), and fat mass was predicted with a standard error of the estimate of 1.7 kg for skinfolds and 2.8 kg for bioelectrical impedance analysis (P?0.001). Fat-free mass was predicted with a standard error of the estimate of 1.7 kg for anthropometry and 2.6 kg for bioelectrical impedance analysis (P?0.001). Regression of various individual skinfolds and summed skinfolds, to examine the eff ect of skinfold selection combinations by stepwise regression, produced an optimal fat mass prediction using the thigh and abdominal skinfold sites, and an optimal fat-free mass prediction using the thigh, abdominal and supra-ilium sites. These results suggest that anthropometry off ers a better way of assessing body composition in athletes than bioelectrical impedance analysis. Applying the derived equations to a separate sample of 24 athletes predicted fat and fat-free mass with a total error of 2.3 kg (2.9%) and 2.2 kg (2.7%), respectively. Combining the samples introduced more heterogeneity into the sample (n=106), and the optimal prediction of fat mass used six skinfolds in producing a similar standard error of the estimate (1.7 kg), although this explained a further 4% of the variation in DXA-derived fat. Fat-free mass was predicted best from four skinfolds, although the standard error of the estimate and coefficient of determination were unchanged.     

Is bioelectrical impedance spectroscopy accurate in estimating changes in fat-free mass in judo athletes?

Abstract Bioelectrical impedance spectroscopy (BIS) provides an affordable and practical assessment of fat-free mass (FFM). However, little information is available on the assessment of changes in fat-free mass in top-level athletes using BIS. The aim of this study was to examine the accuracy of BIS in tracking changes in fat-free mass of elite male judo athletes from a period of weight stability to just before competition, using the four-compartment model (4C model) as reference method. In total, 27 elite male judo athletes (age 22.2?±?2.8 years) were evaluated. Measures of body volume assessed by air displacement plethysmography, bone mineral content by dual-energy X-ray absorptiometry, and total-body water assessed with deuterium dilution were used in a 4C model. Fat-free mass was also assessed by BIS (FFM(BIS)). Changes in FFM(BIS) were not significantly different from measured by the reference method (P?=?0.000). Furthermore, the r (2) was 0.62 and the standard error of the estimate was 1.03 kg. The limits of agreement ranged from -3.36 to 2.59 kg with no bias observed. These findings demonstrate the viability of BIS as a valid tool for tracking fat-free mass in elite male judo athletes. However, based on the wide limits of agreement observed, BIS is less valid at an individual level for tracking fat-free mass in these athletes.     

An investigation of the accuracy and reliability of body composition assessed with a handheld electrical impedance myography device

The purpose of this study was to compare the body fat per cent (BF%) assessed with a unique handheld electrical impedance myography (EIM) device, along with other popular methods, to dual-energy X-ray absorptiometry (DXA). Participants included 33 males (aged 24.3?±?4.6 years) and 38 females (aged 25.3?±?8.9 years) who completed 2 visits separated by 24–72?h. The assessments included DXA, bioelectrical impedance analysis (BIA), skinfold measures (SKF), and three separate EIM measurements. No significant differences in BF% (P?>?0.05) were found between all EIM assessments when compared against DXA for both males and females for each visit. All methods showed no significant differences in BF% (P?>?0.05) between days within themselves. Across both days, the standard error of the estimate (SEE) for the EIM measurements ranged from 2.66% to 3.15%, the SEE for BIA was 2.80 and 2.85, and for SKF was 2.90 and 2.82. The 95% limits of agreement ranged from ±5.34% to ±6.38% for EIM measurements and were highest for SKF (±7.42% and ±7.47%). The total error for both days was largest for SKF (5.20% and 5.35%) and lowest for the EIM measurements (2.48–3.24%). This investigation supports use of a handheld EIM device as an accurate and reliable method of estimating BF% compared to DXA in young, apparently healthy individuals with BF% in the range of 10–22% for males and 20–32% in females and suggests this EIM device be considered a viable alternative to other established field measurements in this population.     

The validity and reliability of relative body fat estimates and the construction of new prediction equations for young Japanese adult males.

The aims of this study were to assess the reliability and validity of three methods of bioelectrical impedance analysis (based on induction between the hand and foot, between one foot and the other foot and between one hand and the other hand) and the skinfold method, and to construct prediction equations for total body density by examining cross-validity in young Japanese adult males. The participants were 50 Japanese males aged 18-27 years (height 1.72 +/- 0.06 m, body mass 64.9 +/- 9.0 kg; mean +/- s), each of whom was measured twice using each of the four methods. Relative body fat based on underwater weighing was used as the criterion for validity. To construct prediction equations for body density, we used multiple regression analysis, whereby all possible combinations were examined. The reliability of all three bioelectrical impedance methods was high (R = 0.999). Three new prediction equations were constructed for the hand-foot method, foot-foot method and skinfold method. The cross-validity of the equations was guaranteed. The relative body fat calculated using the new equations did not differ from that based on the underwater weighing method.     

体质指数法、皮褶厚度法和生物电阻抗法判断青少年超重、肥胖的一致性

运用体质指数法、皮褶厚度法及生物电阻抗法,判断上海城区儿童青少年超重、肥胖发生率及其一致性。结果显示:3种方法在判断不同年龄、性别儿童青少年超重、肥胖上一致性较低;测量原理与精确性不同,青少年儿童体成分化学组成不成熟及诊断、筛查标准的差异可能是3种方法一致性较低的原因。提出应建立适合我国儿童青少年"多维模型"假设下的体脂率预测方程。     

Is bioelectrical impedance spectroscopy accurate in estimating changes in fat-free mass in judo athletes?

Abstract

Bioelectrical impedance spectroscopy (BIS) provides an affordable and practical assessment of fat-free mass (FFM). However, little information is available on the assessment of changes in fat-free mass in top-level athletes using BIS. The aim of this study was to examine the accuracy of BIS in tracking changes in fat-free mass of elite male judo athletes from a period of weight stability to just before competition, using the four-compartment model (4C model) as reference method. In total, 27 elite male judo athletes (age 22.2 ± 2.8 years) were evaluated. Measures of body volume assessed by air displacement plethysmography, bone mineral content by dual-energy X-ray absorptiometry, and total-body water assessed with deuterium dilution were used in a 4C model. Fat-free mass was also assessed by BIS (FFM_BIS). Changes in FFM_BIS were not significantly different from measured by the reference method (P = 0.000). Furthermore, the r ² was 0.62 and the standard error of the estimate was 1.03 kg. The limits of agreement ranged from ?3.36 to 2.59 kg with no bias observed. These findings demonstrate the viability of BIS as a valid tool for tracking fat-free mass in elite male judo athletes. However, based on the wide limits of agreement observed, BIS is less valid at an individual level for tracking fat-free mass in these athletes.     

青春突增期少年身体形态与骨发育的关联研究

本研究随机抽取北京市第27中学的初一、初二年级学生为研究对象,通过国民体质标准测试工具和双能量X线吸收骨密度测量仪对受试者的身体成分及相关形态指标进行测量。结果显示本研究中男生受试者大部分身体形态发育指标均与全身的骨矿含量和骨密度呈高度正相关（P〈0.01）。男、女受试者的瘦体重,肌肉组织重量等与骨量呈高度正相关,而体脂率指标与全身骨矿含量和骨密度都呈较低的相关度。这提示影响青春期少年骨发育的重要因素是其瘦体重及肌肉组织重量,而处于青春突增期的少年体脂率与骨量的多少并无太大相关性。     

健身走运动对老年人体成分的影响

运用生物电阻抗法对实验前后参加健身走运动的老年人和不锻炼的老年人分别进行身体成分测试。实验证明,健身走运动对控体重具有良好作用,并能增加肌肉量,明显减少体脂含量,同时可以降低老年人的身体质量分数（BMI）,有效预防心血管等疾病的发生。     

Mediating effects of resistance training skill competency on health-related fitness and physical activity: the ATLAS cluster randomised controlled trial

The purpose of this study was to examine the mediating effect of resistance training skill competency on percentage of body fat, muscular fitness and physical activity among a sample of adolescent boys participating in a school-based obesity prevention intervention. Participants were 361 adolescent boys taking part in the Active Teen Leaders Avoiding Screen-time (ATLAS) cluster randomised controlled trial: a school-based program targeting the health behaviours of economically disadvantaged adolescent males considered “at-risk” of obesity. Body fat percentage (bioelectrical impedance), muscular fitness (hand grip dynamometry and push-ups), physical activity (accelerometry) and resistance training skill competency were assessed at baseline and post-intervention (i.e., 8 months). Three separate multi-level mediation models were analysed to investigate the potential mediating effects of resistance training skill competency on each of the study outcomes using a product-of-coefficients test. Analyses followed the intention-to-treat principle. The intervention had a significant impact on the resistance training skill competency of the boys, and improvements in skill competency significantly mediated the effect of the intervention on percentage of body fat and the combined muscular fitness score. No significant mediated effects were found for physical activity. Improving resistance training skill competency may be an effective strategy for achieving improvements in body composition and muscular fitness in adolescent boys.     

Validation of a New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry

Skinfold prediction equations recommended by the American College of Sports Medicine underestimate body fat percentage. The purpose of this research was to validate an alternative equation for men created from dual energy x-ray absorptiometry. Two hundred ninety-seven males, aged 18–65, completed a skinfold assessment and dual energy x-ray absorptiometry scan to determine percent of body fat. Three American College of Sports Medicine equations (JP7, JP3a, and JP3b) and the new dual energy x-ray absorptiometry criterion equation were used to predict percent of body fat. Mean age was 32.4 ± 14.0 years and mean BMI was 25.6 ± 3.3 kg/m². The mean dual energy x-ray absorptiometry percent of body fat was 18.0 ± 5.9. The mean percent of body fat for Dual Energy X-Ray Aborptiometry (DC), JP7, JP3a, and JP3b were 19.1 ± 6.3, 16.1 ± 7.4, 14.8 ± 6.8, 15.6 ± 6.7, respectively. The standard error of the estimate of DC was low (2.72%) and was highly correlated (R² = 0.87) with dual energy x-ray absorptiometry. The DC equation more accurately predicted percent of body fat across a general population of men than the recommended American College of Sports Medicine equations.     

Comparison of Female Athlete Triad Coalition and RED-S risk assessment tools

ABSTRACT

The Female Athlete Triad Coalition (Triad Coalition) and Relative Energy Deficiency in Sport (RED-S) consensus statements each include risk assessment tools to guide athlete eligibility decisions. This study examined how these tools categorized the same set of individuals to an overall risk factor score and qualitatively compared athlete eligibility decisions resulting from each tool. Exercising women (n = 166) with complete screening/baseline datasets from multiple previously conducted studies were assessed. Data used for risk assessment included: anthropometric measurements, dual-energy x-ray absorptiometry scans, exercise and health status surveys, and two disordered eating questionnaires (Three Factor Eating Questionnaire and Eating Disorder Inventory). Individuals were scored on each tool and subsequently categorized as either fully cleared, provisionally cleared, or restricted from play. Based on the Triad Coalition tool, 25.3% of subjects were classified as fully cleared, 62.0% as provisionally cleared, and 12.7% as restricted from play. Based on the RED-S tool, 71.7% of subjects were classified as fully cleared, 18.7% as provisionally cleared, and 9.6% as restricted from play. The Triad Coalition and RED-S tools resulted in different clearance decisions (p < 0.001), with the Triad Coalition tool recommending increased surveillance of a greater number of athletes.     

全身与四肢瘦体重3种测量方法结果间的一致性评价——以生存分析与一致性图谱法为例

目的:通过对18~56岁成年人使用生物电阻抗法(BCA I、BCA II)与双能X线吸收测定法(DEXA)测量全身瘦体重(LM)与四肢瘦体重(ALM),明确不同身体成分测量仪测量国人瘦体重分布特征时的差异,详述一致性界限与生存分析法在评价两种或多种方法测量结果间的一致性应用过程。方法:采用BCA I、BCA II与DEXA 3种设备测量163名成年人的身体成分,采用一致性界限与生存分析法评价3种设备测量LM与ALM结果的一致性。结果:男女受试者LM、ALM测量结果在3种测试方法中均具有较高的相关性(P<0.01),BCA I测量结果显著高于BCA II和DEXA,且都具有统计学意义(P<0.05),BCA II与DEXA的一致性程度较好。结论:生存分析与一致性图谱法可用于两种或多种方法测量结果间的一致性评价,两者可结合使用。相对于BCA I,BCA II与DEXA测量值一致性程度更好。     

对生物电阻抗法测定身体成分的评价

采用生物电阻抗法测定身体成分的基本原理，对其主要的测试指标进行了分析评价。认为生物阻抗法简便、准确，可灵敏反应成人减肥效果和运动员的体重控制。同时，可以准确测定儿童的身体成分，为纵向研究提供可靠的数据。