Impaired interlimb coordination is related to asymmetries during pedaling after stroke.

Objective: To understand whether lower limb asymmetry in chronic stroke is related to paretic motor impairment or impaired interlimb coordination.

Methods: Stroke and control participants performed conventional, unilateral, and bilateral uncoupled pedaling. During uncoupled pedaling, the pedals were mechanically disconnected. Paretic mechanical work was measured during conventional pedaling. Pedaling velocity and muscle activity were compared across conditions and groups. Relative limb phasing was examined during uncoupled pedaling.

Results: During conventional pedaling, EMG and mechanical work were lower in the paretic than the non-paretic limb (asymmetry). During unilateral pedaling with the paretic limb, muscle activity was larger, but velocity was slower and more variable than during conventional pedaling (evidence of paretic motor impairment). During uncoupled pedaling, muscle activity increased further, but velocity was slower and more variable than in other conditions (evidence of impaired interlimb coordination). Relative limb phasing was impaired in stroke participants. Regression analysis suggested that interlimb coordination may be a stronger predictor of asymmetry than paretic motor impairment.

Conclusions: Paretic motor impairment and impaired interlimb coordination may contribute to asymmetry during pedaling after stroke.

Significance: Rehabilitation that addresses paretic motor impairment and impaired interlimb coordination may improve symmetry and maximize improvement.