Neuromuscular and Biomechanical Control of Weight Transfer during Gait in Individuals Post-stroke

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Project Summary/Abstract Stroke is the leading cause of long-term disability is the U.S. Individuals post-stroke often have difficulty bearing weight on the paretic lower extremity and transferring weight from one leg to the other. Impaired weight transfer and limb loading contribute to lateral instability and are associated with decreased walking speed and increased risk of falling. Consequently, restoring limb loading and weight transfer ability is an important goal for rehabilitation post-stroke. Despite considerable rehabilitation efforts aimed at enhancing paretic limb loading, their effectiveness on improving neuromotor and functional outcomes remains limited possibly due to poorly understood limb loading mechanisms and the reluctance to use the paretic limb. Multi-planar coordination of neuromuscular actions to regulate loading force during weight acceptance is an important component of functional limb loading. Because abnormal coupling between the sagittal plane knee torque and the frontal plane hip torque accompany direction-specific hip torque weakness has been identified following stroke, it is possible that these abnormalities may impair weight transfer ability. In addition, evidence showed that lateral movements of standing/walking surface triggered reactive responses that increased hip abductor and knee extensor muscle activity, suggesting a potential therapeutic means for inducing hip and knee muscle activity and improving weight transfer and limb loading functions. Accordingly, we propose to apply a continuous lateral oscillation of treadmill to engage hip and knee muscle activity and enhance weight transfer during walking. The long term objective of this project is to develop a mechanism-based framework for designing and testing the effectiveness of novel rehabilitation interventions to enhance lower limb weight transfer and limb loading to improve balance and mobility. This project aims to (1) identify the major limiting factors for regulating limb loading following stroke, (2) determine the immediate effect of treadmill oscillation walking (TOW) on weight transfer characteristics and (3) test the short-term effectiveness of a 6-week TOW intervention on improving weight transfer characteristics, gait function, and self-perceived health outcomes. Kinetic, kinematic, and lower extremity muscle activation patterns will be recorded during walking. We expect that the reduced ability to modulate hip abductor torque is the primary limiting factor of limb loading capacity following stroke. In addition, we expect that compared to baseline, participants with stroke will show increased hip abductor and knee extensor muscle activity and torque production, and increased limb loading rate and reduced weight transfer time during TOW, reflecting that TOW could enhance weight transfer outcomes through improved hip and knee neuromuscular activation. Furthermore, we expect that following 6 weeks of TOW training, participants with stroke will show increased limb loading, decreased weight transfer time, increased walking speed, and improved self-efficacy, suggesting that weight transfer deficits following stroke may be remediated using this novel weight transfer training approach.