Effects of Age-Related Muscle Strength Decline on Biomechanical Parameters of Gait in Older Adults

Introduction: Decline in lower-limb muscle strength is a key factor contributing to reduced functional performance and biomechanical alterations in gait among older adults. This study aimed to examine the relationship between lower-limb muscle strength and spatiotemporal, kinematic, and kinetic gait parameters in the elderly.Methods: In this cross-sectional study, forty adults aged ۶۵ years and older (mean age: ۶۸.۴±۳.۹ years) were assessed. Strength of the quadriceps, dorsiflexors, and plantarflexors was measured using a handheld dynamometer. Three-dimensional gait analysis, spatiotemporal assessment, and surface electromyography were used to evaluate movement patterns and muscle activation. Data were analyzed using Pearson correlation tests, independent t tests, and multiple regression analysis (Enter method).Results: Reduced lower limb muscle strength was associated with slower gait speed (p<۰.۰۰۱, d=۰.۹۴), shorter step length (p=۰.۰۰۲, d=۰.۸۸), and increased double support duration (p<۰.۰۰۱, d=۰.۹۱). The strongest correlation was observed between plantarflexor strength and gait speed (r=۰.۷۲, p<۰.۰۰۱). Ankle joint power during the push off phase showed a significant reduction (p=۰.۰۰۳, d=۰.۸۸). EMG results indicated increased co contraction across all muscles (p<۰.۰۱), reflecting compensatory neuromuscular strategies aimed at enhancing stability. Multiple regression analysis revealed that plantarflexor strength was the strongest predictor of gait speed (Beta=۰.۵۲, p<۰.۰۰۱), with the overall model explaining ۵۸% of the variance (R²=۰.۵۸, p<۰.۰۰۱).Conclusion: Lower limb muscle weakness plays a central role in gait biomechanical changes in older adults, with plantarflexor strength emerging as the strongest predictor of gait speed. Strengthening lower limb muscles—particularly the plantarflexors—should be prioritized in rehabilitation programs to improve mobility and functional performance in the elderly.

کلیدواژه ها:

aging ، lower limb muscle strength ، gait biomechanics ، electromyography ، joint power