Body density estimation from multi-frequency Bioelectrical Impedance Analysis measurements

Introduction: Air plethysmography analysis is a method to measure the human body density (D) and ables to evaluate the body composition. This tool is emerging as a convenient alternative to the hydrostatic weighing. D allows estimation of the Human Fat Mass percentage using typical regression relations (see Siri, 1956). The objectives of the study is to define the relationship between Bioelectrical parameters obtained by Multifrequency Biolectrical Analysis (MF-BIA) and D. Methods: 25 healthy subjects (35 ± 8.2 anni; 1.72 ± 0.08 m; 78.6 ± 15.3 kg) both genders have been enrolled and D measurements have been collected with an Air plethysmography (BODPOD, Cosmed, Italia). Moreover, MF-BIA parameters as Z, PA, Rx and Xc at 5, 10, 50, 100, 250 kHz have been measured (Human in Touch, DSmedica, Italia). Multiply regression analysis has been performed between D and MF-BIA parameters and backward identification method has been used as selection criterion (p < 0.05; software SPSS, IBM, USA). Results: Statistical analysis reports as PA at 50 and 100 kHz are the MF-BIA parameters with best prediction value of D as measured by BODPOD (p < 0.005). The main results (expressed as mean + SD) are: D: 1.038 ± 0.029; D(PA50): 1.041 ± 0.019; D(PA100): 1.036 ± 0.019. Data with an R2adj of 0.394 and 0.442 and a SE of 0.022 and 0.021 for PA50 and PA100, respectively. Conclusions: Phase Angle at 50 kHz and 100 kHz are accurate D predictors. It would seem that the D estimation are slightly higher and lower with PA50 and PA100 respectively. Future investigations on a greater subject number are required to confirm present results and to increase the estimation precision. Moreover, similar studies are necessary to recognise MF-BIA and D relation also in particular categories as well as Obese and diabetic patients.