Frailty and its Association With Strength and Balance Variables in Chilean Older Adults: A Structural Equation Model.

BACKGROUND

Frailty is a geriatric syndrome associated with adverse health outcomes in older adults. However, the specific contribution of neuromuscular factors-including inspiratory strength, lower-limb strength, and balance-to frailty development remains unclear.

PURPOSE: This study aimed to investigate the associations of inspiratory strength, lower-limb strength, and static and dynamic balance with frailty in Chilean older adults.

METHODS

A cross-sectional observational study was conducted in 209 older adults. Frailty was assessed using Fried's phenotype. Inspiratory strength (maximum inspiratory pressure), lower-limb strength (quadriceps peak force and Five Times Sit-to-Stand Test), static balance (posturography), and dynamic balance (Limits of Stability and Timed Up and Go Test) were evaluated. A structural equation model was used to predict a latent frailty variable from age, gender, strength, and balance.

RESULTS

The final structural equation model showed excellent fit (χ2(1) = 3.30, P > .05; comparative fit index = 0.995; root mean square error of approximation = 0.106; Standardized Root Mean Squared Residual [SRMR] = 0.048). Specifically, values of more than 0.95 for the comparative fit index and less than 0.08 for the SRMR are indicative of excellent fit. Inspiratory strength (β = -0.374, P < .01), quadriceps peak force (β = -0.463, P < .01), and dynamic balance (β = 0.439, P < .01) significantly predicted frailty, explaining 79.4% of its variance. Static balance was not a significant predictor.

CONCLUSIONS

Neuromuscular factors, particularly inspiratory strength, quadriceps strength, and dynamic balance, are key factors associated with frailty. Future research should investigate whether interventions focused on inspiratory muscle training, lower-limb strengthening, and functional balance exercises are able to prevent or reduce frailty in older adults.