Assessing variability of postural control over time using nonlinear dynamics

Griffin, Aileen Michelle

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https://hdl.handle.net/2142/110549 Copy

Description

Title

Assessing variability of postural control over time using nonlinear dynamics

Author(s)

Griffin, Aileen Michelle

Issue Date

2021-04-26

Director of Research (if dissertation) or Advisor (if thesis)

• Mejia, Shannon T
• Sosnoff, Jacob J

Department of Study

Kinesiology & Community Health

Discipline

Kinesiology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• postural control
• entropy
• fall risk
• older adults

Abstract

The purpose of this study is to assess the variability of postural sway over time using nonlinear dynamics of ApEn and SampEn. A total of twenty-one participants (age: 78.6 ± 5.7) were recruited and completed thirty days of daily balance assessment, along with a baseline and follow-up assessment. At baseline, measurements of fall risk were taken such as functional tasks of 10 Meter Walk (10MW), Timed Up and Go (TUG), 30-second Sit To Stand (30STS), and underwent a Physiological Profile Assessment (PPA) for fall risk (testing vision, reaction time, proprioception, strength, and sway). Participants were then instructed on the use of a smartphone application, Steady, to perform 4 progressively challenging balance tasks every morning for the following 30 days. The smartphone was placed in the center of the participant’s chest and held vertically for 30 seconds while performing the task. Nonlinear measures of ApEn and SampEn, as well as linear measures of root mean square (RMS) in both the anterior-posterior (AP) and medial-lateral (ML) axes were calculated from the research-grade accelerometer within the smartphone. Upon analyzing the data, participants were placed into either the high risk or low risk for falls based on their initial PPA score (>1.00 indicating elevated fall risk). The values that were calculated included the average maximum (MAX), minimum (MIN), and range of all individuals in the low and high-risk groups, as well as the calculated monthly means compared to the day-to-day means over thirty days. It was found that several high-risk participants had greater day-to-day variability within both linear and nonlinear measures when compared to low-risk participants. The ML axis in the Eyes Closed condition showed the largest difference between groups. This study of pilot data illustrated the emerging use of entropy in quantifying postural control in a unique way using daily assessment.

Graduation Semester

2021-05

Type of Resource

Thesis

Permalink

http://hdl.handle.net/2142/110549

Copyright and License Information

Copyright 2021 Aileen Griffin

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