Article

Although unstable seat methodology has been used to assess trunk
postural control, the reliability of the variables that characterize it remains
unclear. OBJECTIVE: To analyze reliability and learning effect of center of
pressure (COP) and kinematic parameters that characterize trunk postural control
performance in unstable seating. The relationships between kinematic and COP
parameters also were explored. DESIGN: Test-retest reliability design. SETTINGS:
Biomechanics laboratory setting. PARTICIPANTS: Twenty-three healthy male
subjects. METHODS: Participants volunteered to perform 3 sessions at 1-week
intervals, each consisting of five 70-second balancing trials. A force platform
and a motion capture system were used to measure COP and pelvis, thorax, and
spine displacements. Reliability was assessed through standard error of
measurement (SEM) and intraclass correlation coefficients (ICC2,1) using 3
methods: (1) comparing the last trial score of each day; (2) comparing the best
trial score of each day; and (3) calculating the average of the three last trial
scores of each day. MAIN OUTCOME MEASUREMENTS: Standard deviation and mean
velocity were calculated to assess balance performance. RESULTS: Although
analyses of variance showed some differences in balance performance between days,
these differences were not significant between days 2 and 3. Best result and
average methods showed the greatest reliability. Mean velocity of the COP showed
high reliability (0.71 < ICC < 0.86; 10.3 < SEM < 13.0), whereas standard
deviation only showed a low to moderate reliability (0.37 < ICC < 0.61; 14.5 <
SEM < 23.0). Regarding the kinematic variables, only pelvis displacement mean
velocity achieved a high reliability using the average method (0.62 < ICC < 0.83;
18.8 < SEM < 23.1). Correlations between COP and kinematics were high only for
mean velocity (0.45 <r < 0.89). CONCLUSIONS: A familiarization session should be
performed to overcome learning effect. COP parameters showed a better reliability
than kinematics ones. Specifically, mean velocity of COP showed the highest
test-retest reliability, especially for the average and best methods. Although
correlations between COP and mean joint angular velocity were high, the few
relationships between COP and kinematic standard deviation suggest different
postural behavior can lead to a similar balance performance during an unstable
sitting protocol. LEVEL OF EVIDENCE: III.
CI - Copyright (c) 2017 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS