Phase Angle Is Moderately Associated With Muscle Quality and Functional Capacity, Independent of Age and Body Composition in Older Women

There is a growing body of evidence indicating that phase angle (PhA) can be used as an indicator of nutritional status, disease prognosis, and mortality risk; however, it is still unknown whether PhA can be used as an explanator of functional capacity and muscle quality in older women. The main purpose of this cross-sectional study was to explore whether PhA is associated with muscle quality and functional capacity in older women, regardless of total and regional body composition. A total of 125 older women-66.7 (4.7) years; 65.6 (10.9) kg body mass; 156.1 (5.2) cm height; 26.9 (4.0) kg/m body mass index-participated in this study. Anthropometric, PhA, body composition (whole-body dual-energy x-ray absorptiometry) and muscle quality (defined as total muscular strength per kilogram of appendicular lean soft tissue) were measured. The functional capacity was assessed by 4 tests: 10-m walk test, rising from sitting position, rising from ventral decubitus position, and rising from a chair and walking around the house. The summing z-scores for the 4 tests was used as a continuous functional capacity score. Linear regression analysis was conducted to test whether PhA is related to the dependent variables (muscle quality and functional capacity), after adjusting for potential covariates. The PhA presented a small-to-moderate relationship with muscle quality (r = 0.27; P < .01) and functional capacity (r = 0.31; P < .01), respectively. These relationships remained significant after adjustment for age, lower limb lean soft tissue, and total fat mass for muscle quality (β= 0.55; P < .01) and functional capacity (β= 1.38; P < .01). Our findings suggest that healthy elderly women with higher values of PhA have a better muscle quality and functionality, regardless of age and body composition.