Bioimpedance analysis: a useful technique for assessing appendicular lean soft tissue mass and distribution

1 Dipartimento di Informatica e Sistemistica, Università di Roma "La Sapienza," 00184 Roma; 2 Istituto di Analisi dei Sistemi ed Informatica del CNR, 00185 Roma; 3 Istituto di Medicina Interna e Geriatria, Università Cattolica del Sacro Cuore, 00168 Roma, Italy; and 4 Obesity Research Center, St. Luke's Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, New York 10025 The present study was aimed at evaluating the feasibility and reliability of lower limb skeletal muscle (SM) mass estimates obtained by bioimpedance analysis (BIA). BIA estimates were compared with the estimates obtained by dual-energy X-ray absorptiometry (DXA). Ten normal weight and 10 obese women had BIA and DXA evaluations. Lower limb SM mass was then derived from DXA appendicular lean soft tissue estimates. Lower limb SM mass and SM distribution were also estimated from BIA modeling that fits measured resistance values along the leg. SM mass (mean ± SD) was 5.8 ± 1.0 kg by BIA vs. 5.8 ± 1.1 kg by DXA in normal weight subjects and 7.2 ± 1.4 kg by BIA vs. 7.2 ± 1.2 kg by DXA in obese subjects. Mean ± SD of the absolute value of the relative error was 7.0 ± 3.4 and 5.9 ± 3.4% in the two groups, respectively. Similar results were obtained by using five resistance values for the analysis. In conclusion, the proposed BIA model provides an adequate means of evaluating appendicular SM mass. body composition; dual-energy X-ray absorptiometry; bioimpedance analysis; nutritional assessment