Intrasession reliability of center of pressure measures of postural steadiness in healthy elderly people.
OBJECTIVE
To estimate the immediate test-retest reliability of a single measure of several center of pressure (COP) variables, to report the number of trials to be averaged to obtain a reliable measurement of postural steadiness, and to determine the minimal metrically detectable change (MMDC).


METHODS
Cross-sectional study.


METHODS
University biomechanics laboratory.


METHODS
Seven community-living, healthy elderly people over the age of 60 years (range, 62-73y).


METHODS
Not applicable.


METHODS
The COP was estimated from 2 force platforms and the following measures were calculated: (1) root mean square (RMS), (2) COP range, (3) COP mean velocity, (4) mean power frequency (MPF), (5) median power frequency (MedPF), and (6) sway area. Intraclass correlation coefficients (ICCs) were determined by using 9 successive quiet standing trials.


RESULTS
The ICCs obtained for 1 measure of 120 seconds were.58 and.58 for the RMS,.83 and.94 for the COP mean velocity,.52 and.62 for the COP range,.44 and.30 for the MPF, and.34 and.47 for the MedPF in anteroposterior (AP) and mediolateral (ML) directions, respectively. The ICC of the COP sway area obtained for 1 measure was.41. Only 2 trials had to be averaged to obtain an ICC over.90 for the COP mean velocity associated with an MMDC of +/-1.2mm/s (AP) and +/-0.6mm/s (ML).


CONCLUSIONS
Mean velocity was the most reliable COP measure and using 2 repetitions allowed for reliable measurement of postural steadiness. For the other COP variables, 3 trials of 120 seconds were needed to obtain an ICC over.80.
Lafond
Danik
D
Department of Kinesiology, University of Montreal, Downtown Station, Montreal, Quebec H3C 3J7, Canada.
Corriveau
Hélène
H
Hébert
Réjean
R
Prince
François
F
D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011312:Pressure; D011434:Proprioception / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D012046:Rehabilitation / Q000379:methods; D015203:Reproducibility of Results