Reliability of performance measurements obtained using the stability testing and rehabilitation station (STARStation)

The purpose of this study was to determine within- and between-day reliability of measurements of nondisabled subjects for the variables of force and velocity when a balance board (STARStation) was positioned at heights of 4.5 and 7.5 cm from the supporting surface. Twenty-four nondisabled subjects each completed six trials of board rotation at a self-selected velocity. Each trial consisted of 10 revolutions in a clockwise direction. Measurements were repeated within the same day for a second board position, and all tests were completed again on a second day. Descriptive statistics were computed for force and velocity, and intraclass correlation coefficients (ICCs) were calculated. Data were submitted to analyses of variance and follow-up tests. Results showed slight differences between the first three and last three trials. Intraclass correlation coefficients for within-subject reliability for the independent variable day ranged from .72 to .81, and ICCs for within-day reliability for the independent variable trial ranged from .46 to .81. Clinicians using such protocols should be aware of differences within and between days and recognize that measurements will be influenced by the number of trials completed.