Related Experiment Video
Updated: Feb 18, 2026
Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability
Published on: September 18, 2020
Test-retest reliability of linear and nonlinear measures of postural stability during visual deprivation in healthy
Masoud Ghofrani1, Golamreza Olyaei1, Saeed Talebian1
1Physical Therapy Department, School of Rehabilitation, Tehran University of Medical Sciences and Health Services: Piche Shemiran, Enghelab Street, Tehran, PO Box 1148965141, Iran.
Abstract:
[Purpose] The purpose of this study is to evaluate the reliability of linear and nonlinear measures of the center of pressure (COP) during visual deprivation. [Subjects and Methods] Fifteen young adults participated in this study. COP signals were recorded in two conditions: eyes open and eyes closed. Three trials were performed in each condition with a rest period of approximately 1 min. The intraclass correlation coefficients (ICCs) and standard error of measurement (SEM) were calculated. [Results] The investigation of ICC and SEM between trials showed that the Lyapunov exponent (ICC: 0.76-0.96, SEM: 0.03) and total mean velocity (ICC: 0.71-0.95, SEM: 0.05) were more reliable and repeatable than range and area (95% confidence ellipse), while area had the least reliability (ICC: 0.49-0.77, SEM: 0.56). [Conclusion] The Lyapunov exponent can be considered an appropriate postural control index, and the evaluation of postural stability should be done by considering linear and nonlinear tools.
