Submitted to: In Vivo Body Composition Studies International Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 10, 1999
Publication Date: October 7, 1999
Citation: Lukaski, H.C., Hall, C.B., Siders, W.A. 1999. Assessment of regional muscle mass in obese women during weight loss with segmental measurements of bioelectrical impedance(z) [abstract]. Fifth International Symposium on In Vivo Body Composition Studies Program and Abstracts. p.19. Brookhaven national Laboratory, NY. October 7-9, 1999. Technical Abstract: The electrical properties of body components permit the use of bioelectrical impedance analysis (BIA) techniques for the determination of body composition. The resistivities of bone, fat, neurovascular tissues, and skeletal muscle differ considerably which facilitates the estimation of muscle mass, particularly in a defined region or segment of the body. Eight obese women, 22-32 yr, participated in a controlled program of caloric restriction and exercise for 12 wk. Body composition was assessed before and during weight loss with dual x-ray absorptiometry (DXA). Impedance measurements of the right thigh were made by using detector electrodes positioned 15 cm apart on the anterior aspect of the thigh. Source electrodes were placed on the right hand and foot. An 800 uA, 50 kHz AC was introduced at the source electrodes and the voltage drop was determined at the detector electrodes. Bioconductor volume (V) determined with BIA; physical volume of the thigh was calculated by using anthropometric measures. Body mass and fat mass decreased significantly. Fat-free, mineral-free mass changed modestly. Nitrogen balance was positive throughout weight loss. Physical volume of the thigh decreased 25 +/- 3 % (p < 0.001) with no significant change in thigh bioconductor volume (2.1 +/- 0.2 %). Thigh conductor volume was correlated with DXA determinations of muscle mass. Use of regional BIA successfully estimates longitudinal changes in muscle mass during weight loss. These results support the hypothesis that BIA is a valid method to assess regional muscle mass in humans.