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Advisory Committee Chair

David A Brown

Advisory Committee Members

Christopher P Hurt

William K Ogard

Eric P Plaisance

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Individuals with chronic poststroke hemiparesis (PS) exhibit increased variability in spatiotemporal kinematic variables related to endpoint control during walking. For nonimpaired individuals, walking faster or slower than a preferred walking speed, results in less consistent stepping behavior. In three studies I investigated variability in swing phase foot trajectory area on a step-by-step basis (SBS-FTA) in nonimpaired individuals and people with PS. The primary aims of these studies were to 1) validate SBS-FTA in nonimpaired individuals, 2) observe if there was a difference in SBS-FTA variability between nonimpaired individual’s limb, the PS paretic, and nonparetic limbs, and across a wide range of walking speeds, and 3) observe if body weight support (BWS) allowed for more consistent walking patterns and faster walking speed capacity poststroke. Hypotheses: SBS-FTA for all limbs would increase with speed, individuals’ poststroke would have greater SBS-FTA variability and rate increase with speed, and BWS would reduce SBS-FTA variability. Methods: Study 1: I compared stepping kinematic variability measures of step length (SL) and minimum toe clearance (MTC) against SBS-FTA for 15 nonimpaired individuals between 0.35-1.85 m/s speed range. Study 2: I compared SBS-FTA variability of 15 individuals’ PS and 15 healthy individuals during walking (0.35-1.85 m/s). Study 3: I compared SBS-FTA of 10 individuals’ PS during walking (0.35-1.85 m/s) at 0%, 15%, and 30% BWS. Findings: Study 1: SBS-FTA variability increased with speed, had a stronger curvilinear fit compared with the variability of SL and MTC, was more responsive at a given speed, and did not strongly co-vary with SL and MTC variability measures. Study 2: SBS-FTA variability increased with gait speed for all limbs, and at a greater rate for poststroke limbs compared to nonimpaired. Study 3: At some optimal level of BWS, individuals walked faster compared to walking with 0% BWS. SBS-FTA variability increased with speed for both limbs. SBS-FTA increased, rather than decreased, at higher BWS levels for the paretic limb at moderate and maximum walking speeds. Interpretation: Increased SBS-FTA variability may indicate that the gait pattern is becoming less controlled and, gait state-transitions may be necessary at slower speeds or purposefully avoided for people poststroke.

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