ArticlesPostural control in the elderly: An analysis of test-retest and interrater reliability of the COP-COM variable☆,☆☆,★
Section snippets
Subjects
Healthy elderly subjects were recruited from a database of people who showed an interest in studies carried out at the research center.21 They were then contacted by phone to verify their eligibility and to make an appointment if they were interested in participating. The eligibility criteria were to be at or over the age of 60 years, living independently in the community, and having no neurologic or musculoskeletal impairments (eg, history of stroke, transient ischemia attacks, Parkinson's
Results
The study sample consisted of 45 healthy elderly persons and 15 elderly persons with impaired postural control from PDN or stroke. Careful examination of data collection and processing procedures showed a technical problem in the record of 1 impaired subject at the first evaluation. Consequently, test-retest reliability was estimated on 59 subjects. Interrater reliability was estimated using all the subjects because there were no technical problems. The subjects' characteristics are in table 1.
Discussion
The results obtained indicated good reliability of the COP-COM variable for both the test-retest and interrater studies, but varied significantly according to the direction of the COP-COM (AP vs M/L). It is accepted in the literature that postural measures are split in the AP and M/L directions because of the differences between balance control in the sagittal and frontal planes, both from a biomechanic18 and a neural control perspective.30 In the present study, the directional difference in
Conclusion
Postural control is a dynamic phenomenon that changes from day to day. Using the mean of 4 trials of the COP-COM variable stabilizes the COP-COM variable enough to get a reliable measure over a short period of time. An inverted pendulum model involving simultaneous COM and COP records is required to understand how the trajectory and acceleration of the COM in both AP and M/L directions is controlled to maintain postural balance. Using the COP-COM variable provides the opportunity to measure
Acknowledgements
We thank Lise Trottier for the statistical analysis.
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Supported in part by the Medical Research Council of Canada (grant no. MT4343), and the Fonds de la recherche en santé du Québec.
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No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.
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Reprint requests to Hélène Corriveau, PT, MSc, Schl of Rehabilitation Sciences, Physiotherapy, University of Ottawa, 451 Smyth Rd, Ottawa, Ont K1H 8M5 Canada, e-mail: [email protected].
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