Test-Retest Reliability of Multiple Postural Control Assessment Measures

Abstract

Multiple assessment methods exist to identify postural control deficits in both healthy and pathological populations. Though force platform technology is frequently used and validated in quiet stance conditions, few studies have explored the reliability of dual task assessments. Additionally, few studies have utilized non-linear metrics derived from ground reaction forces to determine differences in dual task conditions. PURPOSE: The purpose of this study was to determine test-retest reliability of three different postural control assessments using both linear and nonlinear methodology. METHODS: 24 healthy participants (3 male, 21 female, age 20.38 ± 1.46) attended a single testing session once a week for four weeks. Participants completed three trials of eyes open (EC) and eyes closed quiet standing (EO) and a sport-like postural task, the Wii Fit Soccer Heading Game (WFS). Raw Center of Pressure (CoP) was collected using a force platform (1000Hz) and further analyzed. 95% Confidence Ellipse (CE), along with Peak Excursion Velocity (PEV), and Sample Entropy (SampEn) in anteroposterior (AP) and mediolateral (ML) directions was calculated from the data. Test-retest reliability was assessed using multiple repeated-measures ANOVA for each CoP variable across each time point (Time 1, Time 2, Time 3, Time 4). RESULTS: Significant differences were observed in 95% CE in EO (p =.016) and EC (p =.032) conditions. However, post hoc assessments determined no significant differences between time points 1, 2, 3, or 4. No significant differences were observed for EC PEV in the AP (p =.211) and ML (p =.403) directions, EO in the AP (p =.340) and ML (p =.239) directions, or WFS in the AP (p =.065) and ML (p =.122) directions across time. No significant differences were observed for EC SampEn in the AP (p =.961) and ML (p =.030) directions or EO in the AP (p =.434) and ML (p =.150) directions. CONCLUSIONS: Results indicate that the postural assessment metrics used for EO, EC, and the WFS conditions are a reliable measure across multiple weeks and do not indicate significant variability or a learning effect over time. Use of both linear and non-linear CoP measurements such as SampEn, PEV, and 95% CE show to be reliable over multiple time points, and thus should be taken into consideration for future studies utilizing postural control assessment.