Reliability of center of pressure measures within and between sessions in individuals post-stroke and healthy controls.
BACKGROUND
Knowing the reliability of the center of pressure (COP) is important for interpreting balance deficits post-stroke, especially when the balance deficits can necessitate the use of short duration trials. The novel aspect of this reliability study was to examine the center of pressure measures using two adjacent force platforms between and within sessions in stroke and controls. After stroke, it is important to understand the contribution of the paretic and non-paretic leg to the motor control of standing balance. Because there is a considerable body of knowledge on COP reliability on a single platform, we chose to examine reliability using two adjacent platforms which has not been examined previously in stroke.


METHODS
Twenty participants post-stroke and 22 controls performed an arm raise, load drop and quiet stance balance task while standing on two adjacent force platforms, on two separate days. Intraclass correlations coefficient (ICC2,1) and percentage standard error of measurement (SEM%) were calculated for COP velocity, ellipse area, anterior-posterior (AP) displacement, and medial-lateral (ML) displacement.


RESULTS
Between sessions, COP velocity was the most reliable with high ICCs and low SEM% across groups and tasks and ellipse area was less reliable with low ICCs across groups and tasks. COP measures were less reliable during the arm raise than load drop post-stroke. Within session reliability was high for COP velocity and ML displacement requiring no more than six trials across tasks.


CONCLUSIONS
The COP velocity was the most reliable measure with high ICCs between sessions and the high reliability was achieved with fewer trials in both groups in a single session.
Department of Physical Therapy and Rehabilitation Sciences, University of Maryland, Baltimore, MD 21201, USA.
Vicki L
VL
Gray
Department of Physical Therapy, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Tanya D
TD
Ivanova
Department of Physical Therapy, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada. Electronic address: jayne.garland@ubc.ca.
S Jayne
SJ
Garland
D001132:Arm / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010291:Paresis / Q000150:complications; D010808:Physical Examination; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; D015203:Reproducibility of Results; D012678:Sensation Disorders / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D020521:Stroke / Q000150:complications* / Q000503:physiopathology*
Postural balance; Posture; Reliability; Stroke