Classification of nutritional status by fat mass index: does the measurement tool matter? / Classificação do estado nutricional pelo índice de massa gorda: o instrumento de medição importa?

Abstract Assessment of the Nutritional Status (NS) allows screening for malnutrition and obesity, conditions associated with chronic non-communicable diseases. The fat mass index (FMI) stands out concerning traditional NS indicators. However, proposals that define thresholds for FMI are not sensitive to discriminate extreme cases (degrees of obesity or thinness). Only one proposal (NHANES), determined by total body densitometry (DXA), established eight categories of NS classification (FMI). However, DXA is expensive and not always clinically available. Our study aims to test the validity of the NHANES method using electrical bioimpedance (BIA) and skinfold thickness (ST) to classify NS. The FMI of 135 (69 women) university students aged 18 to 30 years old was determined using DXA, BIA, and ST. The agreement between the instruments (Bland-Altman) and the agreement coefficient in the NS classifications (Chi-square and Kappa index) were tested. The agreement test against DXA indicated that ST underestimated the FMI (-1.9 kg/m2) for both sexes and BIA in women (-2.0 kg/m2). However, BIA overestimated FMI (1.4 kg/m2) in men, although with less bias. There was no agreement between the NS classifications (NHANES) by FMI between DXA and BIA, or DXA and ST. The exception occurred between DXA and BIA in men who showed a slightly better consensus, considered "fair" (k = 0.214; p = 0.001). In conclusion, ST and BIA did not show enough agreement to replace DXA for NS classification, within NHANES thresholds. The FMI measurement tools for the NHANES classification of the categories of NS matters.

Resumo Avaliar o Estado Nutricional (EN) permite rastrear desnutrição e obesidade, condições associadas a doenças crônicas não transmissíveis. O índice de massa gorda (IMG) destaca-se em relação aos indicadores tradicionais de EN. No entanto, propostas que definem limiares para IMG não são sensíveis para discriminar casos extremos (graus de obesidade ou magreza). Apenas uma proposta (NHANES) estabeleceu oito categorias de classificação EN (IMG), mas foi determinada por densitometria corporal total (DXA). Porém, DXA é caro e nem sempre disponível. O objetivo foi testar a validade do método NHANES usando bioimpedância elétrica (BIA) e dobras cutâneas (DOCs) para classificar o EN. O IMG de 135 (69 mulheres) universitários com idade entre 18 e 30 anos foi obtido por DXA, BIA e DOCs. A concordância foi testada entre os instrumentos (Bland-Altman) e classificações de EN (Qui quadrado e índice Kappa). O teste de concordância com a DXA indicou as DOCs subestimarem o IMG (-1,9 kg/m2) para ambos os sexos e a BIA em mulheres (-2,0 kg/m2). No entanto, as BIA superestimaram o IMG (1,4 kg/m2) nos homens, embora com menos viés. Não houve concordância entre as classificações de EN (NHANES) pelo IMG entre DXA e BIA/DOCs. A exceção ocorreu entre DXA e BIA em homens que apresentaram concordância "razoável" (k = 0,214; p = 0,001). Em conclusão, DOCs e BIA não mostraram concordância suficiente para substituir DXA pela classificação de EN, dentro dos limites NHANES. As ferramentas diferem para medir IMG e classificar categorias de EN (NHANES).

Estimating resting energy expenditure from dual-energy X-ray absorptiometry: A cross-sectional study in healthy young adults.

OBJECTIVE: To qualify a 3C approach model of dual-energy X-ray absorptiometry (DXA) to estimate multicomponent resting energy expenditure (REE) referenced by indirect calorimetry (IC). METHODS: A sample of 155 college students, of both sexes (18-30 years old) was evaluated. Anthropometric measures, REE by IC, and whole-body DXA-scans were performed. The REE for each body component was determined after transforming the components from the molecular (DXA) to the organ tissue level. Bland-Altman and proportional bias analyses were used to verify agreement between REE measured (REEIC ) and estimated (REEDXA ). RESULTS: Statistically significant differences were found for all sex comparisons (P < .001), except for age (P = .950). Differences from the final sex-specific models' were not found between REEIC and REEDXA (P > .05). Men also presented greater expenditure (P < .001) in each component, except for adipose tissue. The plots confirmed the validity of the model for both sexes, with low difference values between the measured and estimated REE. The mean of the differences of REEIC and REEDXA showed heteroscedasticity of the data for men (P = .004). The same error tendency was not evident for women (P = .333). CONCLUSIONS: This 3C model, estimating REE from a multicomponent approach, allows a new application of DXA as tool for understanding intraindividual differences in terms of the mass of metabolically active tissue. Sex and populational differences should be taken in account. Consequently, we present qualified sex-specific DXA models that can be applied in different contexts such as health and sports, besides considering interpersonal differences in terms of energy expenditure.

Resistance training with blood flow restriction: Impact on the muscle strength and body composition in people living with HIV/AIDS.

The aim of the study was to compare the impact of 12-week resistance training with blood flow restriction (GRTBFR) versus, traditional resistance training (GTRT) and non-training on the muscle strength and body composition HIV/AIDS participants. Muscle strength was tested at baseline, and on the 6th, 21st and 36th training sessions, using maximal repetition test. Pre- and post-intervention body composition changes were measured by dual-energy X-ray absorptiometry. Resistance training was undertaken three times a week comprising bilateral elbow extension and flexion exercises, unilateral flexion and bilateral knee extension. Changes in strength and body composition (pre- and post-intervention) between groups were evaluated by mixed models of repeated measures, and by paired and unpaired comparisons, considering the Effect Size. All groups were similar at baseline for muscle strength and body composition. Post-intervention, the training groups showed similar, statistically significant increases in muscle strength (GRTBFR=25.7-57.4%; GTRT=24.5-52.3%) and skeletal muscle tissue (GRTBFR=8.4%; GTRT=8.3%). There was also a significant change in body fat (p=0.023-0.043), with significant effect sizes for strength and skeletal muscle tissue (0.41-2.27), respectively. These results suggest that both resistance training interventions promoted muscle hypertrophy, body fat reduction and positive impact on muscle strength in people living with HIV/AIDS. Resistance training with blood flow restriction proved to be an effective alternative to include patients with marked physical weakness, unable to engage in regular strength training programme.ClinicalTrials.gov identifier: NCT02783417.

Population specificity affects prediction of appendicular lean tissues for diagnosed sarcopenia: a cross-sectional study / La especificidad de la población impacta en la predicción de los tejidos magros apendiculares para la sarcopenia diagnosticada: un estudio transversal

INTRODUCTION: sarcopenia is a disease characterized by reduced musculoskeletal tissue and muscle strength. The estimation of appendicular lean soft tissue by DXA (ALSTDXA) is one of the criteria for the diagnosis of sarcopenia. However, this method is expensive and not readily avaiable in clinical practice. Anthropometric equations are low-cost and able to accurate predict ALST, but such equations have not been validated for male Brazilian older adults between the ages of 60 to 79 years. To this end, this study sought to validate the existing predictive anthropometric equations for ALST, and to verify its accuracy for the diagnosis of sarcopenia in male Brazilian older adults. METHODS: this cross-sectional study recruited and enrolled 25 male older adults (69.3 ± 5.60 years). ALSTDXA and anthropometric measures were determined. ALST estimations with 13 equations were compared to ALSTDXA. The validity of the equations was established when: p > 0.05 (paired t-test); standard error of the estimate (SEE) < 3.5 kg; and coefficient of determination r² > 0.70. RESULTS: two Indian equations met the criteria (Kulkarini 1: 22.19 ± 3.41 kg; p = 0.134; r² = 0.78; EPE = 1.3 kg. Kulkarini 3: 22.14 ± 3.52 kg; p = 0.135; r² = 0.82; SEE = 1.2 kg). However, these equations presented an average bias (Bland-Altman: 0.54 and 0.48 kg) and 'false negative' classification for the ALST index. Thus, three explanatory equations were developed. The most accurate equation demonstrated a high level of agreement (r2 adj = 0.87) and validity (r²PRESS = 0.83), a low predictive error (SEEPRESS = 1.53 kg), and an adequate ALST classification. CONCLUSION: anthropometric models for predicting ALST are valid alternatives for the diagnosis and monitoring of sarcopenia in older adults; however, population specificity affects predictive validity, with risks of false positive/negative misclassification

INTRODUCCIÓN: la sarcopenia es una enfermedad caracterizada por una reducción del tejido musculoesquelético y la fuerza muscular. Uno de los criterios utilizados para su diagnóstico es la determinación de tejido blando magro apendicular por DXA (TBMADXA), método costoso que no siempre está disponible en la práctica clínica. Las ecuaciones antropométricas suponen un bajo coste y predicen bien el TBMA, pero con una validez desconocida para los varones brasileños de 60 a 79 años. Por lo tanto, nuestro objetivo fue validar las ecuaciones antropométricas existentes predictivas del TBMA y verificar su precisión para el diagnóstico de sarcopenia en varones brasileños de edad avanzada. MÉTODOS: participaron en este estudio transversal 25 hombres de edad avanzada (69,3 ± 5,60 años). Se determinaron el TBMADXA y las medidas antropométricas. Las ecuaciones predictivas del TBMA se compararon con el TBMADXA. La validez de las ecuaciones en las comparaciones se confirmó cuando: p > 0,05 (prueba de la "t" pareada); error estándar estimado (EEE) < 3,5 kg; coeficiente de determinación r² > 0,70. RESULTADOS: dos ecuaciones indias cumplieron los criterios (Kulkarini 1: 22,19 ± 3,41 kg; p = 0,134; r² = 0,78; EEE = 1,3 kg. Kulkarini 3: 22,14 ± 3,52 kg; p = 0,135; r² = 0,82; EEE = 1,2 kg). Sin embargo, presentaron sesgo promedio (Bland-Altman: 0,54 y 0,48 kg) y clasificación de 'falso negativo' para el índice de TBMA. Por lo tanto, se crearon tres ecuaciones explicativas. La ecuación más precisa mostró un alto acuerdo (r2 adj = 0,87), uma alta validez (r²PRESS = 0,83), um bajo error predictivo (EEEPRESS = 1,53 kg) y uma clasificación del TBMA adecuada. CONCLUSIÓN: los modelos antropométricos para predecir el TBMA son alternativas válidas para el diagnóstico y el seguimiento de la sarcopenia en los ancianos. Pero la especificidad de la población afecta a su validez predictiva, con riesgos de incorrección por clasificación falsa positiva/negativa

Population specificity affects prediction of appendicular lean tissues for diagnosed sarcopenia: a cross-sectional study.

INTRODUCTION: Introduction: the estimation of appendicular lean soft tissue by DXA (ALSTDXA) is one of the criteria for the diagnosis of sarcopenia. However, this method is expensive and not readily avaiable in clinical practice. Anthropometric equations are low-cost and able to accurate predict ALST, but such equations have not been validated for male Brazilian older adults between the ages of 60 to 79 years. To this end, this study sought to validate the existing predictive anthropometric equations for ALST, and to verify its accuracy for the diagnosis of sarcopenia in male Brazilian older adults. Methods: this cross-sectional study recruited and enrolled 25 male older adults (69.3 ± 5.60 years). ALSTDXA and anthropometric measures were determined. ALST estimations with 13 equations were compared to ALSTDXA. The validity of the equations was established when: p > 0.05 (paired t-test); standard error of the estimate (SEE) < 3.5 kg; and coefficient of determination r² > 0.70. Results: two Indian equations met the criteria (Kulkarini 1: 22.19 ± 3.41 kg; p = 0.134; r² = 0.78; EPE = 1.3 kg. Kulkarini 3: 22.14 ± 3.52 kg; p = 0.135; r² = 0.82; SEE = 1.2 kg). However, these equations presented an average bias (Bland-Altman: 0.54 and 0.48 kg) and 'false negative' classification for the ALST index. Thus, three explanatory equations were developed. The most accurate equation demonstrated a high level of agreement (r2adj = 0.87) and validity (r²PRESS = 0.83), a low predictive error (SEEPRESS = 1.53 kg), and an adequate ALST classification. Conclusion: anthropometric models for predicting ALST are valid alternatives for the diagnosis and monitoring of sarcopenia in older adults; however, population specificity affects predictive validity, with risks of false positive/negative misclassification.

INTRODUCCIÓN: Introducción: uno de los criterios utilizados para el diagnóstico de la sarcopenia es la determinación de tejido blando magro apendicular por DXA (TBMADXA), método costoso que no siempre está disponible en la práctica clínica. Las ecuaciones antropométricas suponen un bajo coste y predicen bien el TBMA, pero con una validez desconocida para los varones brasileños de 60 a 79 años. Por lo tanto, nuestro objetivo fue validar las ecuaciones antropométricas existentes predictivas del TBMA y verificar su precisión para el diagnóstico de sarcopenia en varones brasileños de edad avanzada. Métodos: participaron en este estudio transversal 25 hombres de edad avanzada (69,3 ± 5,60 años). Se determinaron el TBMADXA y las medidas antropométricas. Las ecuaciones predictivas del TBMA se compararon con el TBMADXA. La validez de las ecuaciones en las comparaciones se confirmó cuando: p > 0,05 (prueba de la "t" pareada); error estándar estimado (EEE) < 3,5 kg; coeficiente de determinación r² > 0,70. Resultados: dos ecuaciones indias cumplieron los criterios (Kulkarini 1: 22,19 ± 3,41 kg; p = 0,134; r² = 0,78; EEE = 1,3 kg. Kulkarini 3: 22,14 ± 3,52 kg; p = 0,135; r² = 0,82; EEE = 1,2 kg). Sin embargo, presentaron sesgo promedio (Bland-Altman: 0,54 y 0,48 kg) y clasificación de 'falso negativo' para el índice de TBMA. Por lo tanto, se crearon tres ecuaciones explicativas. La ecuación más precisa mostró un alto acuerdo (r2adj = 0,87), uma alta validez (r²PRESS = 0,83), um bajo error predictivo (EEEPRESS = 1,53 kg) y uma clasificación del TBMA adecuada. Conclusión: los modelos antropométricos para predecir el TBMA son alternativas válidas para el diagnóstico y el seguimiento de la sarcopenia en los ancianos. Pero la especificidad de la población afecta a su validez predictiva, con riesgos de incorrección por clasificación falsa positiva/negativa.

Use of allometry and skinfold thicknesses to estimate the fat mass of circumpubertal boys.

Background: In the pubertal period, each part of the body grows at different rates. This makes the relationship between the parts nonlinear. Particularly, the fat mass (FM) of boys tends to decrease, further exacerbating the issue of linearity in growth.Aim: To propose predictive models of FM from skinfolds (SF) adjusted allometrically.Subjects and methods: 75 pubertal boys (14.4 ± 0.9 years) composed the sample by self-selected pubic hair. FM was determined by DXA (FMDXA) (kg), stature (cm), body mass (kg) and nine SF (mm) by anthropometric measurements. The SF were individually adjusted allometrically. FMDXA (Y) values and each anthropometric independent variable-IV (X) underwent logarithmic transformation. Linear regressions were used. The significance of the prediction of the FMDXA of each model (ANOVA) and the concordance analysis (Bland-Altman) were performed.Results: Predictive allometric models of FMDXA showed high determination coefficients (r2) and reduced standard errors of estimation (SEE). The adjusted model involved reduced agreement limits, demonstrating its accuracy.Conclusions: It was possible to propose models with allometric adjustments to estimate FM of pubertal boys. Allometry may aid in the development of predictive linear models of body composition, since it has an indicative capacity of the variables for estimation.

Estimate of Resting Energy Expenditure by DXA in Boys of Different Nutritional Statuses

Abstract Aim: to estimate the resting energy expenditure (REE) of organ tissue components using Dual Energy x-ray Absorptiometry (DXA) in pubertal boys. The mass of components and REE were compared among groups of different nutritional statuses. Methods: a sample of 278 boys (13.7 ± 2.4 years old) was grouped according to BMI nutritional status for Brazilian children and adolescents1 such as Underweight (UW), Normal weight (NW), Overweight (OW), and Obese (OB). The REE of organ tissue components given by DXA was calculated using specific models for skeletal muscle tissue (SMT), adipose tissue (AT), bone tissue (BT) and residual tissue (RT) based on previous reports. The absolute and relative REE (REEDXA) of each component were statistically compared among groups. Results: No differences of total REEDXA were found among nutritional groups (F(3, 274)=0.071, p=0.976). When, however, specific REE was considered per component, differences were found for BT and REEBT between NW-OW (p=0.003) and NW-OB (p=0.048); in AT and REEAT for all the groups (p<0.001), except between UW-NW (p=1.000); in RT and REERT between NW-OB (p=0,022) and SMT and REESMT (p=0,039). Greater proportions of organ tissue of RT and high metabolic rates, were observed in the UW group (78.3%) in comparison to the OB group (60.7%). Conclusion: This approach provides a new opportunity to examine energy metabolism for individual differences of pediatric populations. It is an applicable strategy both to prescribe exercises and to administer diets to this population, as it reveals the magnitude of heat-producing body components.