title: Evaluation of the postural stability of elderly persons using time domain signal analysis.
abstract: A force platform is widely used in the evaluation of postural stability in man. Although an abundance of parameters are typically retrieved from force platform data, no uniform analysis of the data has been carried out. In general, the signal analysis does not analyze the underlying postural event, i.e., whether the signal consists of several small corrections or large excursions. In the present work, we studied the postural stability of 4589 elderly persons from Iceland on a force platform under visual and non-visual conditions during stance on a solid surface. We analyzed the internal relationship between frequently used time domain variables. In addition, we conducted a factor analysis using a subset of selected variables. Factor analysis yielded three components that can be considered different strategies for maintaining posture. In one control strategy, long swaying amplitues were pronounced, allowing the person to react when postural confidence limits are reached. In a second strategy, a high oscillation rate about the stationary point was the dominant characteristic of maintaining postural control. The third strategy appears to involve a short critical time period during which an open loop control changes into a closed loop that very rapidly controls excessive postural oscillations. The findings suggest that conventional parameters such as swaying velocity and amplitude alone do not provide sufficient information regarding a person's ability to maintain an upright stance.
authors.affiliation: Department of Otorhinolaryngology, Tampere University Hospital, Tampere, Finland. jyrki.rasku@uta.fi
authors.forename: Jyrki
authors.initials: J
authors.lastname: Rasku
authors.forename: Ilmari
authors.initials: I
authors.lastname: Pyykkö
authors.forename: Martti
authors.initials: M
authors.lastname: Juhola
authors.forename: Melissa
authors.initials: M
authors.lastname: Garcia
authors.forename: Tamara
authors.initials: T
authors.lastname: Harris
authors.forename: Lenore
authors.initials: L
authors.lastname: Launer
authors.forename: Gudny
authors.initials: G
authors.lastname: Eiriksdottir
authors.forename: Kristin
authors.initials: K
authors.lastname: Siggeirsdottir
authors.forename: Palmi
authors.initials: P
authors.lastname: Jonsson
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Hoffman
authors.forename: Hannes
authors.initials: H
authors.lastname: Petersen
authors.forename: Cuno
authors.initials: C
authors.lastname: Rasmussen
authors.forename: Paolo
authors.initials: P
authors.lastname: Caserotti
authors.forename: Esko
authors.initials: E
authors.lastname: Toppila
authors.forename: Satu
authors.initials: S
authors.lastname: Pajala
authors.forename: Vilmundur
authors.initials: V
authors.lastname: Gudnason
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D004856:Postural Balance; D011187:Posture; D013997:Time Factors