Fatigue and mobility in stroke: a Biomechanical and Neurophysiological Investigation

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The long-term goal of this proposed career development award (CDA-1) is to accelerate the training and development of the PI, allowing him to establish and independent line of research into the etiology and consequences of post-stroke fatigue and dysfunctions of gait and balance. Prior to his collegiate studies the PI served on active duty in the United States Marine Corps for nine years, receiving an Honorable Discharge upon the expiration of his service contract. The PI completed his PhD in Human Bioenergetics at Colorado State University and published 15 manuscripts in peer-reviewed journals during his time there. Since graduating has had another paper accepted and has two manuscripts under review. Currently he is training under the tutelage of Dr. Mark G. Bowden, PT, PhD, at the Ralph H. Johnson VA Medical Center. This proposal will allow the PI to gain the necessary skills needed in neurophysiological assessment and analysis, biomechanical assessment and analysis, and neuroimaging analysis to establish and independent VA backed research program focusing on reducing the impact of fatigue, and gait and balance dysfunctions in healthy and neurologically impaired Veterans. The assembled mentorship team is composed of experts in each of the skillsets the PI is hoping to obtain. Up to 92% of people post-stroke experience fatigue and fatigue negatively affects physical and mental performance and leads to a lower quality of life. Fatigue also affects many other neurological populations of interest to the VA, such as traumatic brain injury and multiple sclerosis. Advances in the knowledge and understanding of post-stroke fatigue may also lead to similar advances in other VA clinical populations. The first aim is to characterize the corticomotor response in Veterans with post-stroke fatigue. The response will be assessed using transcranial magnetic stimulation delivered to the cortical representations of lower extremity muscles, e.g., tibialis anterior and soleus. Fatigue severity and corticomotor response variables will be correlated to establish the link between altered neurophysiology and post-stroke fatigue. We expect to see longer, Lower MEP amplitudes, stimulation latency, and corticosilent periods in participants with high levels of fatigue, signifying a central mechanism of fatigue that can be targeted in future brain stimulation therapies. The second aim of this study is to determine if participants with high levels of fatigue display unique gait biomechanical characteristics. Differences between self-selected and fasted comfortable walking speeds will be calculated for kinetic and kinematic properties of gait. These differences, i.e., walking capacity/reserve, represent a possible behavioral adaptation to post-stroke fatigue to minimize effort due to high perceived fatigue. We expect that Veteran’s with higher reported post-stroke fatigue will walk at a lower percentage (self-selected) of their maximal capacity (fastest comfortable). This aim is expected to identify behavioral consequences of post-stroke fatigue that may exacerbate health outcomes related to poor mobility and physical/social activity participation.