Bioelectrical Impedance Analysis in a Mathematical Model for Estimating Fat-free Mass in Multiple Segments in Elderly Taiwanese Males

SummaryBackgroundThis research applied bioelectrical impedance analysis (BIA) and Dual-Energy X-ray AbsorptioMetry (DXA) to measure the body composition of Taiwan elderly. We developed the new mathematical estimation model for fat free mass of multiple segments.MethodsThe modified BIA instrument with 8 electrodes (BIA8) at 50 kHz and 0.4 mA was used to measure the bioelectrical impedance of whole body and all limb segments of 33 male elderly in Taiwan. The criterion fat free mass (FFM) values in whole body and all limb segments were determined by DXA. After analyzing by linear regression, we obtained the FFM estimation equation for limb segments. The Bland-Altmen analysis were used to evaluate the differences existed between the estimation FFM from equation by BIA and from by DXA.ResultThe correlation efficient (R) with standard deviation (SD) of FFM measured by DXA v.s. estimated by BIA in whole body, lower limbs, upper limbs and trunk were 0.942 with 2.660 kg, 0.859 with 0.713 kg, 0.922 with 0.265 kg and 0.884 with 1.917 kg, respectively. The relative high in the weight coefficients of h2/Z for estimation equation implied the critical role played by height and BIA values.ConclusionIn summary, the multiple segments FFM estimated by BIA were highly relative to that of determined by DXA for elderly in Taiwan. It is feasible to apply in monitoring the body composition in elderly by fast, non-invasive and convenient way.