Neuromechanical Factors That Limit Walking Speed in Individuals with Post-Stroke Hemiparesis

Individuals, post-stroke, present with an array of changes to the neuromuscular system function such as muscle weakness and abnormal muscle activation patterns. Different combinations of these and other altered body functions result in limitations in functional mobility, such as reduced gait speed and high risk for falls. In this series of studies, I developed a deeper understanding of how neuromechanical factors may limit the fastest speed that an individual post-stroke can reach before they are unable to move any faster without losing balance. I conducted three studies. In the first study, my results showed that, after stroke, individuals have the capacity to walk at faster speeds than their overground self-selected maximum walking speed, while walking on a treadmill and when provided horizontal assistance using a robotic device. In the second study, I showed that non-impaired individuals modulated the amplitude and phasing of muscle activity according to the requirements brought about by the existence of horizontal assistive forces during walking at progressively faster speeds. Finally, in the third study I showed that individuals post-stroke also were able to modulate amplitude and phasing of muscle activity in both legs, according to the requirements brought about by the existence of horizontal assistive forces during walking at progressively faster speeds. However, the paretic leg was more responsive to horizontal assistive forces than the non-paretic leg. The understanding gained through these studies provide novel insights regarding the capabilities of individuals with post-stroke hemiparesis to adapt their existing impaired neuromuscular mechanisms into more challenging walking tasks. Each study leads to ideas for the development of potentially more effective rehabilitation protocols targeted at the modulation of amplitude and phasing of muscle activity in order to safely achieve faster walking speeds