Specific bioelectrical vectors pattern in individuals with sarcopenic obesity

Background: Sarcopenic obesity is a common condition in the elderly associated with excessive adiposity and low muscle mass and strength. Aims: This study aims to establish a method for detecting bioelectrical characteristics in individuals with sarcopenic obesity through specific Bioelectrical Impedance Vector Analysis (specific BIVA), while considering the characteristics of individuals with healthy, sarcopenic, and obese conditions. Methods: The sample was composed by 915 Italian adults over 50 years of age (men: 74.6 ± 8.8 y; women:76.3 ± 8.8 y) living in Sardinia (Italy). A dataset of 1590 US adults aged 21 - 49 years retrieved from the 2003 - 2004 National Health and Nutrition Examination Survey was also considered in a final step of the study. Anthropometric (stature, weight, waist, arm, and calf circumferences) and whole-body bioelectrical variables were taken. In the Italian sample, bioelectrical impedance was applied to estimate the relative content of fat mass and skeletal muscle mass. Groups with healthy body composition (NS-NO), or consistent with sarcopenia (S), sarcopenic obesity (S-O), and obesity (O) were defined based on the cut-offs suggested by European expert guidelines (EWGSOP2 and ESPEN-EASO). Specific BIVA was applied to compare groups and to identify the area for sarcopenic obesity within young-adults tolerance ellipses. The position of the specific vector of US individuals with S-O, selected on the basis of DXA measurements, was also considered. Results: In both sexes of the Italian sample, the bioelectrical characteristics of the four groups were different (p < 0.001). The differences were mainly related to vector length, indicative of higher fat mass, which was longer in the O and S-O groups, and phase angle, a proxy of intracellular/extracellular water and muscle mass, lower in the sarcopenic groups. Bioelectrical vectors of the S-O group fell in the right quadrant, outside of the 95 % tolerance ellipses of young adults. The mean vector of the US sample with S-O fell in the same area. Within the S-O area, women had similar bioelectrical values, while men showed phase angle variability, which was related to the severity of the condition. Conclusions: Specific BIVA detects body composition peculiarities of individuals with sarcopenic obesity, thus allowing their diagnosis when associated with low handgrip strength values.