Chumlea W C, Guo S S, Cockram D B, Siervogel R M
Department of Community Health, Wright State University School of Medicine, Dayton, OH, USA.
Am J Clin Nutr. 1996 Sep;64(3 Suppl):413S-422S. doi: 10.1093/ajcn/64.3.413S.
Fat-free mass and total and percentage body fat were determined by dual-energy X-ray absorptiometry (DXA) and total-body and segmental impedance measures were taken at 16 frequencies from 5 to 1300 kHz in a sample of white men and women aged 18-30 y. Plots of total-body and segmental impedance against frequency for each individual indicated that the general shape of these curves was described by the same mathematical function consisting of three components-ai, bi, and ci,-that contain information derived from the individual measurements of impedance summarized across the spectrum of current frequencies. Total-body and segmental multifrequency impedance were significantly correlated with hemoglobin, hematocrit, and serum sodium, potassium, creatinine, and osmolality. Regression models of body composition with total-body or segmental impedance measures at discrete frequencies or the impedance spectrum variables were similar to corresponding findings for impedance models at 50 kHz. The segmental impedance spectrum variables for total and percentage body fat and the ratios of low- to high-frequency impedance from the trunk were significantly associated with total body fatness as measured by DXA.
采用双能X线吸收法（DXA）测定无脂肪体重、总体脂肪量和体脂百分比，并对18至30岁的白人男性和女性样本在5至1300千赫兹的16个频率下进行全身及分段阻抗测量。每个个体的全身和分段阻抗随频率的曲线图表明，这些曲线的总体形状由相同的数学函数描述，该函数由三个分量ai、bi和ci组成，这些分量包含从当前频率范围内汇总的阻抗个体测量中得出的信息。全身和分段多频阻抗与血红蛋白、血细胞比容以及血清钠、钾、肌酐和渗透压显著相关。使用离散频率下的全身或分段阻抗测量值或阻抗谱变量建立的身体成分回归模型，与50千赫兹时阻抗模型的相应结果相似。全身脂肪量和体脂百分比的分段阻抗谱变量以及来自躯干的低频与高频阻抗之比，与通过DXA测量的总体肥胖程度显著相关。
