Association of electrical properties of bioelectrical impedance spectroscopy with sedentary time, physical activity and muscle function in older adults

Abstract Introduction Little is known about the relationship between cell health indicators measured by the bioelectrical impedance spectroscopy (BIS) electrical properties such as phase angle (PhA), characteristic frequency ( f c ), and membrane capacitance ( C m ) and objective indicators of sedentary time, physical activity levels, and muscle function among older adults. This study examined the BIS parameters and their association with sedentary time, physical activity, and muscle function. Methods Data from 96 older adults were used. The BIS electrical properties, physical activity, grip strength, short physical performance battery (SPPB), and timed-up-and-go (TUG) were assessed, after which multiple regression analyses were conducted. Results The findings showed that individuals with normal phase angle (PhA) scores exhibited greater light physical activity, daily activity counts, grip strength, and SPPB scores compared to those with low PhA. PhA and membrane capacitance ( C m ) showed a negative correlation with sedentary time and TUG and a positive correlation with low physical activity, grip strength, and SPPB. The characteristic frequency ( f c ) was positively correlated with sedentary time and negatively correlated with low physical activity and grip strength. Multiple regression analyses showed that only PhA was the significant predictor of sedentary time, low physical activity, total activity counts per day, SPPB, and TUG. Conclusion Results suggest that PhA may serve as a useful adjunctive indicator of physical activity and functional status among older adults.