Extracellular water-to-total body water ratio is an essential confounding factor in bioelectrical impedance analysis for sarcopenia diagnosis in women

Key summary points Aim To examine the relationships of extracellular water-to-total body water ratio (ECW/TBW) with handgrip strength, gait speed, and skeletal muscle mass index (SMI) in older women. Findings This study reveals an association between SMI and handgrip strength in community-dwelling older women with ECW/TBW values less than 0.40, although there was no such association in women with ECW/TBW values of 0.40 or higher. Message The ECW/TBW ratio represents a confounding factor, which should be considered when using bioelectrical impedance analysis for sarcopenia diagnosis. Purpose The extracellular water-to-total body water ratio (ECW/TBW) is used in bioelectrical impedance analysis (BIA) for measuring muscle mass; however, ECW/TBW may be affected by several factors common in older individuals. Here, we assessed the relationships of ECW/TBW with handgrip strength, gait speed, and skeletal muscle mass index (SMI) in older women. Methods In this cross-sectional study, 73 community-dwelling women aged ≥ 65 years who could independently perform activities of daily living were included. ECW/TBW was measured using direct segmental multifrequency BIA. The participants were divided into ECW/TBW