Ageing alters ankle mechanics and muscle co-contraction patterns across the gait cycle

The ankle plays a central role in stability and propulsion during walking. Ageing alters muscle–tendon properties and neural coordination, disrupting the relationship between neuromuscular control and mechanical output. What are the age-related changes in tibialis anterior and gastrocnemius normalised electromyography signals, sagittal-plane ankle angle and moment, and braking–propulsive ground reaction force across the walking gait cycle? A secondary analysis was conducted on 107 healthy able-bodied adults aged 26–86 years who walked overground at self-selected speed while three-dimensional motion capture, force platforms and surface electromyography recorded movement data. Time-normalised gait cycle data were analysed using one-dimensional Statistical Parametric Mapping simple linear regressions to examine continuous age-related effects. Increasing age was associated with increased tibialis anterior–gastrocnemius co-contraction during early and mid-stance and reduced co-contraction in terminal stance. Older adults exhibited greater dorsiflexion in late stance and pre-swing, reduced plantarflexion moments in mid-stance, and lower braking and propulsive ground reaction forces. With increasing age, normalised gastrocnemius electromyography signal within the gait cycle increased in early stance even as plantarflexion moments declined, reflecting a stabilising motor-control strategy that compensates for reduced proprioceptive acuity. Ageing induces phase-specific ankle motor-control adaptations that maintain stability but reduce mechanical efficiency and propulsion. These changes likely contribute to slower gait, greater fatigue and elevated fall risk. Interventions should target neuromuscular timing, phase-specific coordination, proprioception and muscle–tendon function to restore propulsion without compromising stability. • Ageing alters ankle mechanics and phase-specific patterns of normalised electromyography signals across the gait cycle. • Ankle agonist-antagonist muscle co-contraction rises with age, aiding joint stability. • Late-stance plantarflexion and propulsion decline due to muscle-tendon changes.