Interactive effects of age and lower-limb muscle strength asymmetry on spatiotemporal gait parameters

Ageing is associated with gait deterioration, yet the influence of lower-limb muscle asymmetry on age-related gait changes remains unclear. This cross-sectional study investigated the interaction effects of age and lower-limb muscle strength asymmetry on spatiotemporal gait parameters in 345 community-dwelling adults aged 19-85 years. Lower-limb muscle strength was assessed using a hand-held dynamometer, and gait parameters were measured using an inertial measurement unit. Spearman correlation and multiple regression analyses examined associations between strength asymmetry and gait metrics, with interaction terms testing age-dependent effects. Age was associated with reduced stride length and some variability measures. Muscle asymmetry effects varied by joint: knee asymmetry correlated with spatial measures (stride length), while ankle asymmetry linked to temporal measures (stance, swing, and double support phases). Notably, knee extension asymmetry was associated with shorter stride length only in elderly participants, and ankle plantarflexion asymmetry was linked to poorer temporal symmetry exclusively in older adults, with no effects observed in younger groups. These findings suggest that lower-limb strength asymmetry, combined with ageing, is selectively associated with greater gait deterioration. Assessment of bilateral strength balance, beyond absolute strength levels, may be relevant to understanding gait stability in older adults and may inform targeted intervention strategies for fall prevention.