Human Movement
On Friday 8 February 2008, the Orthopaedic/Rehabilitation sessions on Human Movement will feature a Keynote Address by Steven A. Kautz Ph.D., University of Florida, Gainesville, FL.
Theoretical and Experimental Analyses of Walking in Persons with Post-stroke Hemiparesis
Stroke is the leading cause of long-term disability with less than 50% of surviving stroke patients walking in the community. Much work has been done in our lab towards the ultimate goal of improving rehabilitation of walking in persons with post-stroke hemiparesis. Our research program integrates advanced impairment assessment methods and enhanced movement analysis techniques with predictive biomechanical and comprehensive neuromotor control models to provide a framework for investigating and ultimately obtaining optimal functional outcomes from interventions to optimize movement control. Our research currently addresses four complementary questions: how do muscles coordinate rhythmic locomotor behavior like walking, what is the best way to quantify walking performance, what are the specific functional deficits in muscle coordination of walking in persons with post-stroke hemiparesis, and how does rehabilitation influence muscle coordination in persons with post-stroke hemiparesis? We are addressing these questions through:
- experimental investigations of locomotor control,
- combined experimental and theoretical modeling studies on the specific deficits of hemiparetic walking, and
- clinical investigations of the underlying mechanisms of response to locomotor rehabilitation.
A focus in our lab has been on the development and refinement of theoretically based measures of motor performance at the biomechanical and neuromotor control levels. We have previously developed paretic propulsion (the percent of the total propulsion produced by the paretic leg) as an integrative biomechanical measure of the coordinated performance of the paretic leg. In this study we present the development of a set of neuromotor measures from hemiparetic walking data to integrate with our biomechanical measures. There is currently much interest in analyses to identify common elements of multiple muscle EMG patterns to represent the fundamental building blocks (basis functions) of movement [1-2]. As an example of ongoing work in our lab, we are currently investigating applying the non-negative matrix factorization technique [2] to extract muscle synergy groupings and timing patterns. We hypothesized that hemiparetic walking could be explained with fewer basis functions than walking in healthy control subjects, and that each basis function could be correlated with performance measures during walking as represented by ground reaction forces or joint moments.
[1] Ivanenko et al. (2004). J Physiol. 556: 267-282
[2] Ting et al. (2005). J Neurophysiol 93:609–613
Steven A. Kautz is Director of the Human Motor Performance Laboratory at the Department of Veteran’s Affairs Brain Rehabilitation Research Center of Excellence in Gainesville, FL, and an Associate Professor in the Department of Physical Therapy at the University of Florida in Gainesville, FL. He directs the Human Motor Performance Laboratory for the UF Brooks Center for Rehabilitation Sciences in Jacksonville, FL.
Dr. Kautz earned his B.S in Geophysics from Michigan State University, his MA in Geophysics from the University of Texas, and his Ph.D. in Biomedical Engineering from the University of California in Davis, CA. He did his postdoctoral training at the VA Rehabilitation Research and Development Center, Palo Alto, CA, and continued at the center as a Principal Investigator for a total of ten years before moving to his current positions.
Dr. Kautz’s academic interests are in the areas of neural control and biomechanics of human locomotion in healthy persons and in persons with neurological disorders such as stroke and incomplete spinal cord injury. His studies employ experimental and theoretical analyses and range from cross-sectional investigations to identify deficits in the control of locomotion and their implications for functional performances to longitudinal studies of the effects of rehabilitation interventions designed to improve walking performance. He has been principal investigator on numerous NIH and Department of Veteran’s Affairs funded research projects and his research is currently supported by two NIH R01 grants and two VA Merit Review grants investigating walking persons with neurological disorders. He is an author of 45 papers in international peer-reviewed scientific journals, and more than 80 contributions to conferences. Dr. Kautz has served as a grant reviewer for the NIH, Department of Veteran’s Affairs, American Heart Association, and the Science and Technology Foundation, Portugal Ministry of Science and Technology.
