Sit-to-Stand as an
Evaluation Tool for Balance
Department of Veterans Affairs Health Care System
Rehabilitation R&D Center
Palo Alto, CA 94304
Difficulty with sit-to-stand
(STS) is one of several neuromuscular performance risk factors associated with
multiple falls. People with Parkinson's disease (PD) have been shown to exhibit
a prolonged duration of STS when compared with normal healthy elders (NE). The
purpose of this study was to determine whether a quantitative measure of
sit-to-stand correlates with increased falls risk. Twenty NE and 17 PD subjects
were asked to perform 14 balance tasks varying in difficulty from sitting
balance to one-legged stance. Tasks were scored using a 2-3 point scale for a
maximum qualitative balance score (QBS) of 23 points. Subjects also completed a
self-report falls history from which a fall injury index (FI) was derived. STS
was performed at normal speed, arms crossed (arms ok if otherwise unable), and
recorded using a wearable accelerometric motion analysis system. The averaged
right and left waist vector magnitudes were utilized to identify the time of
momentum transfer (tmin-tmax) and to identify normal and abnormal patterns of
accelerometric patterns. In normal the maximum directly preceeds the minimum
(peak ID (PI)=0). This marks the start (max) and end (min) of momentum transfer
during STS. An abnormal pattern the max peak follows the min (PI=2) or preceeds
the min by more than 2 peaks (PI=1) A high FI (fallers) correlated moderately
with both a low QBS (Pearon's r=.68) and a high PI (r=.77) score. While
subjects with PD (.98 + 1.10 sec) did take longer to perform the momentum
transfer stage of STS than NE (.58 + .12 sec) the difference was not
significant. Accelerometric analysis of STS shows potential for falls
prediction in different elder populations.
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