Association of Lower-Limb Muscle Strength and Range-of-Motion Asymmetry with Functional Performance Indicators 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 among lower-limb muscle strength asymmetry, range of motion (ROM) asymmetry, motor performance, and functional limitations in older adults.
Materials and Methods: In this cross-sectional study, 67 older adults (mean age: 71.01 ± 4.80 years) were recruited via convenience sampling from the Kahrizak Charity Foundation, Tehran, Iran. Lower-limb muscle strength was measured with a handheld dynamometer, and joint ROM with a goniometer; asymmetry indices were calculated for each. Motor performance was assessed using the Timed Up-and-Go test, 10-meter walk test, Balance Error Scoring System, and Tinetti test. Falls and functional limitations were evaluated via a fall-history questionnaire and basic/instrumental activities of daily living (BADL/IADL) measures. Associations were analyzed using Pearson's and Spearman's correlation coefficients (α = 0.05).
Results: Lower-limb muscle strength asymmetry showed no significant association with motor performance or functional limitations (P > 0.050). Most ROM asymmetry indices were also non-significant. 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 significantly associated with walking speed (r = 0.268, P = 0.029) and functional limitations (r = 0.254, P = 0.038).
Conclusion: Lower-limb muscle strength asymmetry was unrelated to functional indicators, whereas hip adduction and extension ROM asymmetry were associated with several functional measures. These findings suggest that the association between lower-limb asymmetry and functional performance in older adults depends on the specific joint movement involved.