Análise comparativa de parâmetros físicos e funcionais e fatores associados a estabilidade postural dinâmica em pessoas idosas

Abstract

Introduction: With aging, the decline in physical and functional parameters in older adults may be accentuated by physical frailty. Older adults with impaired trunk and lower limb strength, static and reactive balance may have impaired ability to remain stable during gait. Thus, this study proposed two objectives. The first objective was to compare muscle strength, dynamic stability, balance, ability to transfer from sitting to standing, fear of falling and history of falls among robust, pre-frail and frail older adults. The second objective was to investigate whether trunk and lower limb strength, static and reactive balance are associated with dynamic postural stability of older adults with different frailty phenotypes. Methods: Cross-sectional study with 159 community-dwelling older adults classified by frailty phenotype. Isometric muscle strength of trunk extensors, hip extensors and abductors, knee extensors, and ankle plantar flexors was assessed using a hand-held dynamometer. Dynamic postural stability during gait was measured by the Functional Gait Assessment. Static balance was assessed by the single-leg balance test and the modified clinical test of sensory interaction and balance, and reactive balance was assessed by correction with a compensatory forward step. The ability to transfer from sitting to standing was assessed by the 5-times sit-to-stand test. Fear of falling and history of falls were also assessed using the Falls Efficacy Scale-International and self-reported falls in the last year, respectively. Analysis of covariance and regressions were used for statistical analysis. Results: Frail older adults had lower trunk and lower limb muscle strength (p < 0.05; effect size [ES] = 0.87-1.05), worse static balance (p < 0.001; ES = 1.72-1.88), reactive balance (p = 0.004; OR = 9.29), dynamic postural stability (p < 0.001; ES = 2.25), ability to transfer from sitting to standing (p < 0.001; ES = -2.18), greater fear of falling (p < 0.001; ES = -2.11) and history of falls (p = 0.014; OR = 7.73) compared to robust individuals. Pre-frail older adults had lower lower limb muscle strength (p < 0.05; TE = 0.44-0.45), single-leg balance (p < 0.001; TE = 0.81), worse reactive balance (p = 0.006; OR = 3.28), dynamic postural stability (p = 0.049; TE = 0.50) and ability to transfer from sitting to standing (p = 0.005; TE = -0.92) compared to robust individuals. The strength of trunk extensors, hip extensors and abductors, knee extensors and ankle plantar flexors were associated with postural stability in gait (p < 0.05; R2 from 0.47 to 0.48; β from 2.9 to 6.2). Static single-leg balance (p < 0.0001; β = 0.154), sensory interaction and balance (p = 0.007; β= 0.048) and severe reactive response (p < 0.001; β = -3.851) also showed a significant association with the postural stability of elderly people during gait (R2 = 0.63). Conclusion: The presence of physical and functional alterations not only in frail older adults, but also in pre-frail older adults, suggests that these parameters should be incorporated into the evaluation of this population. In older adults, higher muscle torque values and better performance in static balance tests were associated with greater postural stability during gait. Furthermore, older adults who presented severe reactive response in the reactive balance test presented worse postural stability during gait than older adults with normal reactive response. Keywords: ageing; physical frailty; muscle strength; balance; postural stability.