Phase angle is independently associated with muscle strength and agility in community-dwelling older women: a cross-sectional study.

BACKGROUND: Age-related declines in muscle strength and functional performance are key determinants of loss of independence in older adults. Phase angle (PA), derived from bioelectrical impedance analysis, has emerged as a potential indicator of cellular health; however, its relationship with functional performance in older women remains insufficiently explored. OBJECTIVES: To investigate the association between PA and functional performance in community-dwelling older women. METHODS: This cross-sectional study included 213 older women (mean age 69 ± 6 y). Participants were stratified into tertiles according to PA values. Functional performance was assessed using tests of single-leg balance, agility, and lower limb strength, while upper limb muscle strength was evaluated by handgrip dynamometry. Associations between PA, age, and functional outcomes were examined using correlation analyses and multiple linear regression models. RESULTS: Participants in the lowest PA tertile demonstrated significantly poorer performance across all functional tests (P < 0.05). PA was significantly correlated with balance (r = 0.205), agility (r = -0.272), lower limb strength (r = 0.266), and handgrip strength (r = 0.320, all P < 0.01). In adjusted regression analyses, PA remained independently associated with lower limb strength (β = 0.235; P = 0.001), handgrip strength (β = 0.248; P < 0.001), agility (β = -0.195; P = 0.001), and balance performance (β = 0.128; P = 0.045). CONCLUSIONS: PA derived from bioelectrical impedance analysis was independently associated with muscle strength, agility, and balance in community-dwelling older women and may serve as a non-invasive physiological indicator associated with muscle strength and physical function.