Qual a variação percentilar da força neuromuscular em pessoas idosas determina o declínio da velocidade de caminhada a longo prazo? Evidências do English Longitudinal Study of Ageing

Abstract

Population aging brings significant challenges to maintaining mobility, which is essential for independence and quality of life. Neuromuscular strength (NS), commonly measured by handgrip strength (HGS), is recognized as a crucial factor in maintaining mobility in older adults, and when reduced, it is an indicator for identifying individuals at risk of mobility decline. However, conventional cutoff points used to measure HGS ignore percentile variations over time, limiting the effectiveness of early detection of the risk of functional decline. Objective: This longitudinal study aimed to investigate the relationship between percentile variation in neuromuscular strength (NS) and decline in walking speed (WS) in older adults over twelve years of follow-up. Methodology: The study was conducted with 4,541 participants from the ELSA Study, all aged 60 years or older. NS was measured by handgrip strength (HGS), and its variation over four, eight, and twelve years relative to the baseline was classified into groups: maintained NS within ±5%, increased NS by 5% to 10%, 10% to 15%, 15% to 20%, or more than 20%, as well as reduced NS by the same percentages. Generalized linear mixed models were used to analyze WS trajectories in meters per second (m/s) based on NS variations, adjusted for sociodemographic, behavioral, and clinical characteristics. Results: Participants who reduced NS by 15% to 20% (-0.007 m/s per year, 95% CI: -0.013 to -0.002) and more than 20% (-0.004 m/s per year, 95% CI: -0.007 to -0.001) showed a greater decline in WS over time compared to those whose NS remained stable (± 5%). This resulted in a decline of -0.189 m/s and -0.144 m/s in WS, respectively, over twelve years. Conclusion: A loss of 15% or more in NS is associated with a reduction in WS. The implications of this study highlight the need for more dynamic and individualized monitoring of NS in clinical practice, enabling earlier and more personalized preventive interventions to minimize mobility decline and, consequently, preserve the functional independence of older adults.