RESUMO
abstract Children with a deficit of growth because of perinatal malnutrition present specificities in the percentage of body fat (%BF) that could not be detected by previous fat mass-based equations. This study developed and validated predictive equations of the %BF derived from anthropometric variables in children aged 7 to 10 living in Northeast Brazil, using dual-energy x-ray absorptiometry (DXA) as a reference. Body composition data from 58 children were utilized. DXA was used as a reference. A stepwise (forward) multiple regression statistical model was used to develop the new equations. The Bland-Altman analysis (CI: 95%), paired Student's t-test, and the intraclass correlation coefficient (ICC) was used to validate and compare the developed equations. Two new equations were developed for either gender: boys: %BF: 13.642 + (1.527*BMI) + (-0.345*Height) + (0.875*Triceps) + (0.290* Waist Circumference) and girls: %BF: -13.445 + (2.061*Tight). The Bland-Altman analysis showed good agreement, with limits ranging from -1.33 to 1.24% for boys and -3.35 to 4.08% for girls. The paired Student's t-test showed no difference between %BF-DXA and the two new equations (p> 0.05), and the ICC was 0.948 and 0.915, respectively. DXA-based anthropometric equations provide an accurate and noninvasive method to measure changes in the %BF in children.
resumo Crianças com déficit de crescimento por desnutrição perinatal apresentam especificidades na distribuição do percentual de gordura corporal (%GC) que não puderam ser detectadas por equações anteriores baseadas no %GC. Este estudo desenvolveu e validou equações preditivas do %GC derivadas de variáveis antropométricas em crianças de 7 a 10 anos residentes no Nordeste do Brasil, utilizando como referência a absorciometria radiológica de dupla energia (DXA). Foram utilizados dados de composição corporal de 58 crianças. O DXA foi usado como modelo de referência. Um modelo estatístico de regressão múltipla stepwise (forward) foi usado para desenvolver as equações. A análise de Bland-Altman (IC: 95%), teste t de Student pareado e o coeficiente de correlação intraclasse (CCI) foram utilizados para validar e comparar as equações. Duas novas equações foram desenvolvidas para ambos os sexos: meninos: %GC: 13,642 + (1,527*IMC) + (-0,345*Altura) + (0,875*Tríceps) + (0,290* Circunferência da cintura) e meninas: %GC: - 13,445 + (2,061*coxa). A análise de Bland-Altman mostrou boa concordância, com limites variando de -1,33 a 1,24% para meninos e -3,35 a 4,08% para meninas. O teste t de Student pareado não mostrou diferença entre %GC-DXA e as duas novas equações (p>0,05), e o CCI foi de 0,948 e 0,915, respectivamente.
RESUMO
BACKGROUND: Birthweight (BW) has been associated with anthropometry, body composition and physical fitness during growth and development of children. However, less is known about the mediation effect of those variables on the relationship between BW and basal metabolic rate (BMR) in children. OBJECTIVE: To analyse the mediation effect of anthropometry, body composition and physical fitness on the association between BW and BMR in children. METHODS: In total, 499 children (254 boys, 245 girls) aged 7-10 years were included. Anthropometry (weight, height, head, waist and hip circumferences), body composition (skinfolds thickness, body fat percentage), physical fitness (handgrip strength, flexibility, muscular endurance, muscular explosive power, agility, running speed) and BMR were evaluated. The analyses were conducted by: single-mediator analysis (SMA) and multi-mediator analysis (MMA). RESULTS: The SMA indicates height, head, waist and hip circumferences and handgrip strength as significant mediators of BW on BMR for boys and height, hip circumference and handgrip strength as significant mediators of BW on BMR for girls. In MMA for girls, there were significant indirect effects for height, hip circumference and handgrip strength, with 79.08% of percent mediation. For boys, the head and waist circumferences mediation had a significant indirect effect, with 83.37% of percent mediation. CONCLUSION: The anthropometric variables associated with BW were body height, head, hip and waist circumferences for boys and body height and hip circumference for girls. The current study provides new evidence that height and handgrip strength during childhood mediated the relationship between BW and BMR.