Potential muscle function during the swing phase of stroke gait.

The understanding of individual muscle impairments that affect swing phase in stroke gait will lead to better rehabilitation strategies for this population. We used induced acceleration analysis to evaluate the potential each muscle has to accelerate the hip and knee joints of the swing limb, using kinematics from three stroke subjects and five healthy subjects. To determine the influence of altered limb position on muscle function, we augmented hip extension by 10 degrees in swing phase for all subjects. We found that in early swing, healthy subjects had greater potential to accelerate the knee into flexion than stroke subjects, whereas stroke subjects had greater potential to accelerate the hip into flexion. Perturbing the hip flexion angle into greater extension increased the potential of biarticular muscles to flex the knee in swing phase. The potential of muscles to improve swing phase dynamics depends on the initial posture of the limb and highlights the importance of subject-specific evaluations in the design of appropriate therapeutic interventions.