Phase Angle and Impedance Ratio as Indicators of Physical Function and Fear of Falling in Older Adult Women: A Cross-Sectional Analysis (Preprint)

Abstract

Older adults experience a significant decline in muscle quality and function with aging. Phase angle (PhA) and impedance ratio (IR) measured via bioelectrical impedance analysis (BIA) are both indicative of physical function and cellular health.

This study aim is to characterize the relationships between hand grip strength (HGS), sit-to-stand (STS), BTrackS balance scores, fear of falling (Short FES-1), and IR among older adult women classified as having low or high PhA.

A cross-sectional analysis was conducted in 85 older women with a mean age of 75.38 (SD 7.16) years, weight of 71.59 (SD 16.06) kg, and height of 162.74 (SD 6.18) cm. To examine the influence of PhA on performance measures, participants were divided into two PhA groups, high (>4.1°; n=56) and low (≤4.1°; n=29). Data were non-normative, so Mann-Whitney U test was used to evaluate between-group differences and Kendall’s tau coefficients were utilized to determine the partial correlations.

The low PhA group had significantly higher IR (P<.001, rrb=0.92). The high PhA group had greater HGS (P=.007, rrb=0.36), BTrackS balance scores (P =.03, rrb=0.30), and STS scores (P<.001, rrb=0.49) compared to the low PhA group. When adjusted for age among the whole sample, PhA was strongly correlated with HGS (τb=0.748, P=.003) and STS scores (τb=0.764, P=.002). Short FES-1 scores were moderately correlated with IR (τb=0.456, P=.07).

Results revealed that the low PhA group had significantly higher IR, while the high PhA group demonstrated greater HGS, BTrackS balance scores, and STS scores. Notably, when adjusted for age, PhA showed strong correlations with HGS and STS scores. These findings suggest that lower PhA values, indicative of reduced cellular health, are associated with diminished physical function in older women. Therefore, PhA may serve as a valuable tool for early identification of older individuals at risk of functional decline.

ClinicalTrials.gov (NCT06063187)

RR2-10.2196/27381