Faculty Collaboration Database

Instantaneous postural stability characterization using time-frequency analysis. Gait Posture 1999 Oct;10(2):129-34

Date

09/30/1999

Pubmed ID

10502646

DOI

10.1016/s0966-6362(99)00023-5

Scopus ID

2-s2.0-0032841830 (requires institutional sign-in at Scopus site)   32 Citations

Abstract

Postural stability assessment is critical to a more accurate understanding of sway and balance control. The center of pressure (COP) metric has been shown to be a suitable output measure for time and frequency analysis. However, the center of pressure is a non-stationary signal. Standard time and frequency analysis methods may not be adequate for monitoring the dynamic changes in the center of pressure signal. In this study a time-frequency method, based on data-adaptive evolutionary spectral estimation, is applied to monitor the dynamic changes of the center of pressure in a non-stationary environment. Metrics including the instantaneous mean frequency (IMF), instantaneous spectral bandwidth (ISB), and instantaneous average power (IAP) are analyzed to characterize the center of pressure signal in both the anterior-posterior (AP) and the medial-lateral (ML) planes. Within the confines of this study, the IMF was found to be inversely proportional to IAP. The inverse proportionality factors were calculated in both eyes-open and eyes-closed trials during upright quiet standing. These findings suggest that the time-frequency analysis provides instantaneous metrics which describe the amplitude changes and frequency shift of the center of pressure under a variety of environmental conditions, thus providing a more reliable quantification of postural control.

Author List

Ferdjallah M, Harris GF, Wertsch JJ

Author

Gerald Harris PhD Director in the Orthopaedic Research Engineering Center (OREC) department at Marquette University

MESH terms used to index this publication - Major topics in bold

Adult
Female
Humans
Male
Muscle, Skeletal
Postural Balance
Posture