Association of Lower-Limb Muscle Strength and Range-of-Motion Asymmetry with Motor Performance Indices in Older Adults: A Cross-Sectional Study

Introduction: Motor function decline is a key contributor to reduced independence in older adults. This study examined associations between lower-limb muscle strength and range of motion (ROM) asymmetry with motor performance and functional limitations in the elderly.
Materials and Methods: IIn this cross-sectional study, 67 older adults (mean age: 71.01 ± 4.80 years) were recruited via convenience sampling from the Kahrizak Charity Foundation in Tehran City, Iran. Lower-limb muscle strength was measured with a handheld dynamometer, and joint ROM was assessed using a goniometer; asymmetry indices were then calculated. Motor performance was assessed using the Timed Up and Go (TUG) test, 10-Meter Walk Test (10MWT), the Balance Error Scoring System (BESS), and the Tinetti Performance-Oriented Mobility Assessment (POMA). Falls and functional limitations were evaluated via a fall-frequency questionnaire and basic/instrumental activities of daily living (BADLs/IADLs) measures, respectively. Associations between variables were analyzed using Pearson's and Spearman's correlation coefficients, with statistical significance set at P < 0.05.
Results: LLower-limb muscle strength asymmetry showed no significant association with motor performance or functional limitations (P > 0.05). Most ROM asymmetry indices were also not significantly associated with functional outcomes. However, hip adduction ROM asymmetry correlated significantly with walking speed (r = −0.668, P = 0.001), fall frequency (r = 0.606, P = 0.001), static balance (r = 0.285, P = 0.019), and dynamic balance (r = −0.424, P = 0.001). Hip extension ROM asymmetry was also significantly associated with walking speed (r = 0.268, P = 0.029) and functional limitations (r = 0.254, P = 0.038).
Conclusion: LLower-limb muscle strength asymmetry was not significantly associated with the functional outcomes examined, whereas hip adduction and extension ROM asymmetries were associated with several functional measures. These findings suggest that the functional significance of lower-limb asymmetry may vary according to the type of joint movement.