Article

Postural control is often assessed by quantifying the magnitude of the center of
pressure (COP) movement. However, these measures usually focus on the gross
amount of movement and ignore the temporal structure of the COP signal. A novel
non-linear analysis technique was recently developed to characterize the temporal
structure of the COP signal with an output termed the entropic half-life
[E(1/2)]. The E(1/2) reflects how much of the previous postural position is used
to determine the current postural control strategy (memory effect).
The purpose of this study was to quantify the E(1/2) and four COP movement magnitude
measurements (medio-lateral and anterior-posterior excursion, path length, 95%
ellipse area) for balance tasks increasing in sensory difficulty, as well as the
test-retest reliability of each measure. Twenty-seven healthy young adults
completed single limb stance tasks varying in sensory difficulty (rigid surface
eyes open, rigid surface eyes closed, foam surface eyes open) on two separate
occasions. Relative reliability was assessed using an intraclass correlation
coefficient (ICC3,3). Absolute reliability was assessed using the standard error
of the measurement (SEM) and the sensitivity of the measurement to true changes
was assessed using the minimal detectable change (MDC95). The E(1/2) was found to
have excellent reliability for all tasks tested (ICC range 0.82-0.91, SEM range
3.5-14.1 mm, MCD95 range 9.7-39.2 mm). The high reliability of the E(1/2) was
comparable to that of movement magnitude measurements. This may be used in order
to better understand the underlying motor control system.
CI - Copyright (c) 2014 Elsevier B.V. All rights reserved.

Langue : ANGLAIS