Clinical factors associated with ankle muscle coactivation during gait in adults after stroke.

BACKGROUND: Increased ankle muscle coactivation during gait represents an adaptation strategy to compensate for postural instability in adults after stroke. Although increased ankle muscle coactivation is correlated with gait disorders in adults after stroke, it remains unclear which physical impairments are the most predictive clinical factors explaining ankle muscle coactivation during gait. OBJECTIVE: To investigate these physical impairments in adults after stroke using stepwise multiple regression analyses. METHODS: The magnitude of ankle muscle coactivation during gait was quantified with a coactivation index (CoI) for the first and second double support (DS2), and single support (SS) phases in 44 community-dwelling adults after stroke. Paretic motor function, sensory function, spasticity, ankle muscle strength, and balance ability were evaluated. RESULTS: The regression analysis revealed that the balance ability and paretic ankle plantarflexor muscle strength were significant factors determining the CoI during the SS phase on the paretic side. For the CoI during the DS2 phase on the paretic side, only the balance ability was selected as a significant factor. CONCLUSION: Adults with impaired balance ability and paretic ankle muscle weakness after stroke used a compensation strategy of increased ankle muscle coactivation on the paretic side to enhance postural stability during gait.