• Locomotor Adaptation to a Novel Unilateral Swing Phase Perturbation in Nondisabled Individuals and Persons with Chronic Stroke and Hemiparesis

      Savin, Douglas N., Jr.; Morton, Susanne M.; Whitall, Jill (2011)
      Human walking must be flexible given the myriad of behavioral goals and conditions in which it occurs. Alterations to gait often occur after stroke and asymmetries of post-stroke gait such as step length and single limb support have shown little improvement with traditional therapeutic interventions. Contrasting gait's inherent flexibility with the resistance of hemiparetic gait asymmetries to intervention begs the question: to what extent are hemiparetic gait asymmetries alterable? Therefore, the purpose of this dissertation was to test a novel form of locomotor adaptation designed to specifically alter gait symmetry and determine mechanisms of adaptive interlimb coordination in nondisabled and subjects with stroke and hemiparesis. We recorded electromyography and spatiotemporal gait parameters during treadmill and overground walking as subjects adapted their gait to a novel unilateral swing phase perturbation. In study one we tested whether changes in the leg opposite the unilateral perturbation during treadmill walking were caused by practice-dependent adaptation or feedback corrective mechanisms. Nondisabled subjects demonstrated adaptations and aftereffects of multiple gait parameters and electromyography bilaterally. In study two we tested whether locomotor adaptation of spatial and temporal gait parameters was impaired in subjects with stroke and hemiparesis compared to nondisabled controls. Subjects with stroke had similar adaptations of spatial and temporal gait parameters regardless of which leg was perturbed compared to controls. After removal of the perturbation, negative aftereffects resulted in subjects with stroke initially walking with single limb support symmetry. In study three, we tested the extent to which step length symmetry adaptation during a 10-minute bout of treadmill walking generalized to overground. Both nondisabled and subjects with stroke generalized step length symmetry to overground walking. Negative aftereffects in subjects with stroke indicated they were capable of walking with step length symmetry overground. In summary, our results show feedforward changes in the leg opposite a unilateral perturbation, that locomotor adaptation is not impaired by stroke and hemiparesis and locomotor adaptation during treadmill walking is capable of generalizing to overground walking in nondisabled subjects and those with stroke and hemiparesis. These results suggest that motor adaptation may be beneficial in the rehabilitation of stroke-induced gait asymmetries.