Abstract
Background: One of the major objectives of stroke rehabilitation is to
enhance balance control. Therefore, it is crucial to have standardized and reliable balance measures to pinpoint areas for rehabilitation. This study examines the between-day and within-day reliabilities of the center of pressure (CoP) measures in chronic stroke survivors in different standing positions during the effect of motor and cognitive loads.
Methods: Sixteen people (49.31±15.5 years, 5 females) with chronic stroke were assessed in two sessions, 48 hours apart in three conditions: single-task, motor dual-task, and cognitive dual-task. In each condition, three trials of open-eyes quiet standing and three trials of semi-tandem standing were completed, while in the single task condition, three trials of closed-eyes quiet standing were also done. Intraclass correlation coefficient (ICC2,3), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated for CoP mean velocity, mean velocity in the anterior-posterior (AP) and medial-lateral (ML) directions, the standard deviation of AP and ML velocity, and sway area.
Results: Within-day ICC values were higher than between-day values (ICCs ranged from 0.78 to 0.96). Mean velocity and mean and SD of velocity in the AP direction showed the highest relative (ICC: 0.82 and 0.92, 0.83 and 0.90, and 0.84 and 0.90, respectively) and absolute reliabilities (SEM: 0.74 and 1.24, 0.67 and 0.84, and 0.87 and 1.08) in an open-eyes quiet standing position. Dual-task performance could also increase the reliability of the CoP measures, except for the sway area (ICC:0.53-0.93 changed to 0.84-0.96). The semi-tandem standing position was the least reliable position in a single-task condition (ICC:0.53-0.89).
Conclusions: CoP measures during various positions and conditions have sufficient reliability in chronic stroke survivors. Assessing the postural control system during dual-task conditions provides more reliable CoP measures, especially in a semi-tandem standing position.