Reliability of Force-Platform Measures of Postural Sway and Expertise-Related Differences

in Journal of Sport Rehabilitation
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Although reliability is a population-specific property, few studies have investigated the measurement error associated with force-platform parameters in athletic populations.


To investigate the skill-related differences between athletes and nonathletes in reliability of center-of-pressure (COP) summary measures under eyes-open (EO) and eyes-closed (EC) conditions.


Test–retest reliability study.


COP was recorded during double-leg quiet standing on a Kistler force platform before and after a fatiguing treadmill exercise, with EO and EC.


31 male participants including 15 athletes practiced in karate and 16 nonathletes.

Main Outcome Measures:

Standard deviation (SD) of amplitude, phase-plane portrait, SD of velocity, mean total velocity, and area were calculated from 30-s COP data. Intraclass correlation coefficient (ICC), standard error of measurement, and coefficient of variation (CV) were used as estimates of reliability and precision.


Higher ICCs were found for COP measures in the athlete (compared with the nonathlete) group, postfatigued (compared with prefatigued) condition, and EC (compared with EO) tests. CVs smaller than 15% were obtained for most of the COP measures. SD of velocity in the anteroposterior direction showed the highest reliability in most conditions.


Tests with EC and to a lesser extent tests performed in the athlete group and in the postfatigued condition showed better reliability.

Meshkati is with the Science and Research Branch, Islamic Azad University, Tehran, Iran. Namazizadeh is with the Khorasgan Branch, Islamic Azad University, Isfahan, Iran. Salavati is with the Dept of Physical Therapy, University of Social Welfare and Rehabilitation, Tehran, Iran. Mazaheri is with the Musculoskeletal Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.