A time-in-boundary analysis on postural stability between older adults with and without kinesiophobia

Kinesiophobia in older adults can affect postural stability, though literature on sensitive measurements and functional mobility remains inconsistent.

To investigate differences in normalized stability times, measured by various Time-in-Boundary (TIB) thresholds, when considering functional mobility based on the Timed Up and Go (TUG) test between older adults with and without kinesiophobia.

Observational feasibility study of a cross-sectional design.

Thirty-five older adults with kinesiophobia and 38 control subjects completed the dominant limb standing task on a platform in eyes-open and eyes-closed conditions. The primary outcome was TIB, which is the proportion of time a subject's center of pressure (COP) stays within predefined radial thresholds (10 mm-30 mm) from the average COP position. This was calculated across anteroposterior (AP) and mediolateral (ML) dimensions to assess postural stability.

There were significant differences in visual conditions (F = 64.28, p = 0.001) and thresholds (F = 295.16, p = 0.001) as well as interactions between visual conditions and thresholds (F = 18.05, p = 0.001). The TUG test results, used as a covariate, showed a significant interaction on thresholds (F = 16.35, p = 0.001) and visual conditions x thresholds (F = 4.36, p = 0.04) for the normalized stability times.

Visual input and smaller COP thresholds (<20 mm) are critical in differentiating postural stability between groups, particularly under eyes-open conditions. Older adults with kinesiophobia exhibited reduced stability and slower TUG performance. Clinicians should consider TIB thresholds and visual context when assessing balance and functional mobility.