# Combining neurophysiology and biomechanics to delineate post-stroke gait impairments

> **NIH NIH R01** · UNIVERSITY OF TEXAS AT AUSTIN · 2020 · $436,138

## Abstract

PROJECT SUMMARY
Following stroke, numerous impairments develop that affect walking ability. We lack a clear understanding of
what characterizes these impairments and their relation to impaired walking ability. For example, we applied
exoskeletal knee flexion to assist those with reduced knee flexion post-stroke. The assistance improved knee
flexion but surprisingly worsened compensatory motions such as hip abduction. Preliminary analysis indicated
that the assistance elicited hyperexcitable quadriceps reflex activity. Additionally, the quadriceps response was
abnormally coordinated with hip abductor muscles only in post-stroke individuals. These results question
traditional beliefs regarding which motions are compensatory and which are due to neural impairment. Thus,
the critical gap to restoring functional gait post-stroke is characterizing the interconnection between
biomechanical issues and neural impairments. Our novel approach is to combine state-of-the-art methods in
biomechanics and neurophysiology to develop cause-and-effect models of the interconnection between gait
kinematics, hyperexcitable reflex activity and abnormal coordination. The clinical significance is the
groundwork for targeted interventions such as reflex modulation and neurally intelligent exoskeletons that
interact with the impaired spinal circuitry. It will be shown in our preliminary work that we have years of
experience characterizing post-stroke gait impairments using reflex stimulation, robotics and computational
methods that uniquely qualify our group for this project.
 The objective of this proposal is to establish the biomechanical and neurophysiological mechanisms
underlying pathological gait post-stroke. In Aim 1, we determine whether hip abduction is a compensation for
reduced knee flexion by comparing people with stroke to induced similar walking patterns in healthy
individuals. Muscle activation patterns and intralimb coordination will provide evidence towards fundamental
differences in neural control after stroke. In Aim 2, we use reflex neurophysiological methods to probe post-
stroke individuals’ reflex coordination patterns. We expect to find that hyperactive quadriceps reflexes are
associated with impaired knee flexion. We additionally expect to show the interrelation between reflex activity
in the quadriceps and the abductors as predicted by our models representing abnormal coordination. In Aim 3,
we use reflex conditioning protocols during gait based on sophisticated paired peripheral nerve stimulation
techniques. These methods will provide evidence of the spinal mechanisms at the root of abnormal reflex
behavior that likely underlie impaired gait post-stroke. Together this comprehensive testing procedure
incorporates biomechanics and neurophysiology to reveal new knowledge of post-stroke gait impairment.
These results will have broad impact on our understanding of neuromuscular impairments and enable the
development of targeted therapies for treatment...

## Key facts

- **NIH application ID:** 10052892
- **Project number:** 1R01HD100416-01A1
- **Recipient organization:** UNIVERSITY OF TEXAS AT AUSTIN
- **Principal Investigator:** James Sulzer
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $436,138
- **Award type:** 1
- **Project period:** 2020-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10052892

## Citation

> US National Institutes of Health, RePORTER application 10052892, Combining neurophysiology and biomechanics to delineate post-stroke gait impairments (1R01HD100416-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10052892. Licensed CC0.

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