Center-of-pressure based postural sway measures: Reliability and ability to distinguish between age,fear of falling and fall history

The purpose of this study was to compare the test-retest reliability of a wide variety of center-of-pressure (CoP) based postural sway measures and their ability to detect the differences between the young and older groups (age comparison), between the older low- and high-fear of falling groups (fear of falling comparison), and between the older non-faller and faller groups (fall history comparison). Forty healthy females (twenty each in both young and older groups) performed three trials of bipedal quiet standing on a force platform, in which eighteen reported CoP based measures were computed from recorded CoP trajectory. Intra-class correlation coefficient (ICC), standard error of measurement (SEM) and %SEM were used to quantify their relative and absolute reliability. Fear of falling and retrospective falls of the older group were recorded using falls efficacy scale-international (FES-I) and the history of falls questionnaire respectively. Experimental results showed that eight measures (RMS distance, RMS distance-AP, mean velocity, mean velocity-AP, mean frequency, mean frequency-AP, phase plane parameter and fractal dimension) had acceptable levels of relative and absolute reliability. Three measures (RMS distance-AP, mean velocity, and phase plane parameter) were sensitive to detect age-group difference and fear of falling under both visual conditions, but no single measure was capable to detect differences between the non-faller and faller groups.Relevance to industryThe results of this research provide useful information on the selection of appropriate center-of-pressure (CoP) based postural sway measures to assess individual's balance ability for preventing the occupational falls.