Test–retest reliabty of center of pressure measures of postural stability during quiet standing in a group with musculoskeletal disorders consisting of low back pain, anterior cruciate ligament injury and functional ankle instability

Department of Physical Therapy, University of Social Welfare and Rehabilitation, Tehran, Iran.
Gait & posture (Impact Factor: 2.75). 02/2009; 29(3):460-4. DOI: 10.1016/j.gaitpost.2008.11.016
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ABSTRACT Reliability is a population-specific property, but to the authors' knowledge there has been no study to determine the test-retest reliability of the postural stability measures such as center of pressure (COP) measures in the population of patients with musculoskeletal disorders (MSDs), while their clinical applications have been presented in literature. So, 33 patients with low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI) randomly completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed) in two sessions. COP data were used to calculate standard deviation of amplitude, standard deviation of velocity, phase plane portrait, mean total velocity and area (95% confidence ellipse). Relative reliability of these measures was assessed using intraclass correlation coefficient (ICC) and absolute reliability using standard error of measurement (SEM) and coefficient of variation (CV). Also, minimal metrically detectable change (MMDC) was calculated to quantify intervention effects. Among different COP parameters, mean total velocity in all conditions of postural difficulty showed high to very high reliability, with ICC range of 0.74-0.91, SEM range of 0.09-0.40cm/s, CV range of 5.31-8.29% and MMDC range of 0.19-0.79cm/s. Phase plane portrait in anteroposterior-mediolateral (AP-ML) and ML direction were other best parameters with respect to the level of reliability. Mean total velocity and phase plane portrait parameters are suggested as good candidates to use for quantification and assessment of balance performance and identifying those with MSDs.

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Available from: Soheil Sohani, Sep 28, 2015
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    • "ICCs depend on between-subject variability [14] and ''only have meaning when applied to specific populations'', according to Streiner and Norman [15]. The level of reliability is populationspecific [13] and has not yet been evaluated for VI individuals. Accepted measures of postural stability in standing balance characterize the variability of human movement [16]. "
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    ABSTRACT: Individuals with visual impairment (VI) have irreparable damage to one of the input streams contributing to postural stability. Here, we evaluated the intra-session test-retest reliability of the Wii Balance Board (WBB) for measuring Center of Pressure (COP) magnitude and structure, i.e. approximate entropy (ApEn) in fourteen legally blind participants and 21 participants with corrected-to-normal vision. Participants completed a validated balance protocol which included four sensory conditions: double-leg standing on a firm surface with eyes open (EO-firm); a firm surface with eyes closed (EC-firm); a foam surface with EO (EO-foam); and a foam surface with EC (EC-foam). Participants performed the full balance protocol twice during the session, separated by a period of 15 minutes, to determine the intraclass correlation coefficient (ICC). Absolute reliability was determined by the standard error of measurement (SEM). The minimal difference (MD) was estimated to determine clinical significance for future studies. COP measures were derived from data sent by the WBB to a laptop via Bluetooth. COP scores increased with the difficulty of sensory condition indicating WBB sensitivity (all p < 0.01). ICCs in the VI group ranged from 0.73 to 0.95, indicating high to very high correlations, and the normal group showed moderate to very high ICCs (0.62-0.94). The SEM was comparable between groups regardless of between-subject variability. The reliability of the WBB makes it practical to screen for balance impairment among VI persons.
    Gait & Posture 12/2015; 41(In Press). DOI:10.1016/j.gaitpost.2014.11.012 · 2.75 Impact Factor
    • "used . In the present study , mVel has showed good intrasession reliability in a protocol that used sample durations of only 30 s ( Le Clair & Riach , 1996 ; Schmid et al . , 2002 ) . Furthermore , this var - iable produced very good values of intrasession reliability despite the experimental conditions . These results agree with those obtained by Salavati et al . ( 2009 ) . In their study , they assessed the postural stability during quiet standing in a group with musculoskeletal disorders consisting of low back pain , anterior cruciate ligament injury and functional ankle instability , and the mean total velocity in all condi - tions of postural difficulty showed high to very high reli - ability . Tho"
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    ABSTRACT: The authors' aim was to determine which variables allow for the characterization of motor balance behavior. Traditional measures and nonlinear measures of center of pressure (COP; n = 30) and kinematics (n = 10) were tested in their absolute and relative consistency in a 30-s standing balance task protocol under stable and unstable conditions. Regarding COP variables, mean velocity (mVel), permutation entropy (PE) and detrended fluctuation analysis (DFA) exhibited high consistency between trials and ranked individuals more accurately compare with other metrics. In the kinematic signal mVel, PE and DFA had good intrasession reliability values in unstable conditions. Overall, the intrasession reliability values were better in the unstable condition than in the stable condition and the measures calculated using derived data had better intrasession reliability values. In conclusion, mVel, PE, and DFA allow for the good characterization of motor balance behavior in a simplified protocol where velocity time series are analyzed.
    Journal of Motor Behavior 05/2015; 47(6):1-13. DOI:10.1080/00222895.2015.1014545 · 1.42 Impact Factor
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    • "The first and last 5 seconds of each measurement are trimmed in order to discard any transient effects, resulting in measurements of 30 seconds . The trimmed data is then filtered using an 8th order Butterworth filter with a cut-off frequency of 10 Hz to remove any high frequency noise, which (Salavati et al., 2009 "
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    ABSTRACT: In this paper, a tool to assess a person’s fall risk with the Nintendo Wii Balance Board based on Center of Pressure (CoP) recordings is presented. Support Vector Machine and K-Nearest Neighbours classifiers are used to distinguish between people who experienced a fall in the past twelve months and those who have not. The classifiers are trained using data recorded from 39 people containing a mix of students and elderly. Validation is done using 10-fold cross-validation and the classifiers are also validated against additional data recorded from 12 elderly. A cross-validated average accuracy of 96.49% +/- 4.02 is achieved with the SVM classifier with radial basis function kernel and 95.72% +/- 1.48 is achieved with the KNN classifier with k = 4. Validation against the additional dataset of 12 elderly results in a maximum accuracy of 76.6% with the linear SVM.
    International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC), Lisbon, Portugal; 01/2015
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