Assessing variability of postural control over time using nonlinear dynamics

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Kinesiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2021

Author dc:creator

• Griffin, Aileen Michelle

Contributors dc:contributor

• Mejia, Shannon T
• Sosnoff, Jacob J

• postural control
• entropy
• fall risk
• older adults

Statement dc:rights

• Copyright 2021 Aileen Griffin

Language dc:language

en

Handle dc:identifier

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

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/110549