Phase angle and functional performance in older women

This study was conducted to investigate the relationship between phase angle and functional capacity in older women. The main objective was to evaluate the influence of the phase angle on the performance the functional tests of grip strength, agility, and lower limb strength. Secondary objectives included analyzing the correlations between phase angle and different measures of physical performance.

Inclusion criteria were: women over 60 years old, physically independent, and cognitively preserved (Mini-Mental State Examination >23). The total sample included 213 physically independent older women divided into tertiles (n=71 per group, mean age 68.05 ± 5.45 years) based on the phase angle value (t1, 5.32°; t2, 6.06°; t3, 6.94°), measured by tetrapolar bioelectrical impedance (BIA 310e, Biodynamics). Three functional tests were performed: (1) Grip strength with a digital dynamometer (Takei T.K.K. 5401 Grip-D); (2) Agility/balance dynamics using the AGILEQ test; (3) 30s sit-to-stand test, and (4) 30s one-legged stance test. Statistical analysis included comparisons between phase angle tertiles (one-way ANOVA) and correlations (Pearson) between phase angle and test outcomes.

Overall, participants in t3 achieved better performance in the tests. The AGILEQ (p 0.007), sit-to-stand (p 0.001), and one-legged stance (p 0.042) tests had significant differences between t1 and t3. There was a significant difference in grip strength between t1 and t3, as well as between t2 and t3 (p 0.002). Regarding correlations, the results showed weak to moderate positive correlations between phase angle and grip strength (r = 0.31, p 0.01), sit-to-stand (r = 0.27, p 0.01), and one-legged stance (r = 0.23, p 0.01), while there was a moderate negative correlation between phase angle and the AGILEQ test (r = -0.32, p 0.01).

The study showed that phase angle is associated with muscle strength, agility, and balance in physically independent older women. Phase angle may be used in clinical practice as a complementary tool for assessing the functional capacity of older women and for the early identification of functional decline.

The results have implications for geriatric physiotherapy because phase angle can be incorporated into the assessment of functional risk in older adults, contributing to the management and promotion of health among alder adults.