Abstract

Muscle impairments that affect the swing phase of gait and lead to stiff-knee gait and foot drop are widespread issues in the stroke population. In order to formulate the best rehabilitation strategies, comprehension of the individual role each muscle plays during swing is critical. The goal of this study was to advance the understanding of individual muscle potential during swing in stroke gait. We used an induced acceleration analysis (IAA) tool to evaluate the potential each muscle has to accelerate the hip and knee joints of the swing limb, using gait kinematics collected from three stroke subjects and five healthy subjects. We further applied IAA after perturbation of the hip flexion angle, in order to directly observe the influence of altered limb position on muscle function. We found that in all subjects, the muscles known to contribute most to limb movement also generally had the greatest potential for joint acceleration, supporting the logical supposition that the muscles most equipped to move the body are actually utilized. We also found that in early swing, healthy subjects had greater potential to accelerate the knee into flexion than stroke subjects, while stroke subjects had greater potential to accelerate the hip into flexion. Perturbing the hip flexion angle into greater extension increased the potential of gluteus medius (GMED) and gluteus minimus (GMIN) to accelerate the hip into abduction in all stroke subjects; however, in healthy subjects, the posterior compartment of GMED showed the opposite effect. Our results demonstrate the value and convenience of using our IAA tool in analyzing the potential role of each muscle. Furthermore, the differences found between subjects emphasize the importance of subject-specific evaluations when using gait analysis to evaluate a stroke patient for future treatment.