Article

OBJECTIVE: To investigate abdominal and low back muscle activation amplitudes of
older adults (at least 50 years of age) experiencing nonspecific chronic low back
pain (LBP) and of adults without LBP while they walked on a level surface at a
self-selected speed. DESIGN: Cross-sectional. SETTING: Dynamics of human motion
laboratory. PARTICIPANTS: Nine asymptomatic control participants (mean +/-
standard deviation: 64.9 +/- 8.8 years) and 9 participants experiencing LBP (61.4
+/- 9.8 years) were selected for this study. METHODS: Surface electromyography
(EMG) was recorded over the bilateral lower rectus abdomini, internal obliques,
lateral erector spinae longissimus, and lumbar multifidus muscle sites while
participants walked across a pressure-sensor mat at a self-selected speed. To
normalize EMG amplitudes during gait, the participants performed a series of
maximal voluntary isometric contractions. EMG signals were full-wave rectified
and low-pass filtered to yield a linear envelop waveform. For the gait trials, a
window was identified from right heel strike to the second left heel strike and 4
subphases, including right and left loading response and mid stance, were
identified. EMG amplitudes were calculated for each subphase. MAIN OUTCOME
MEASUREMENTS: Two sample t-tests compared demographic information and
spatiotemporal gait parameters between groups. EMG activation amplitude
differences between groups and among subphases of gait were analyzed for each
muscle with use of general linear models, followed by Tukey honestly significant
difference post hoc comparisons. RESULTS: No differences were found between the
groups for demographic or gait parameters. The control group participants
activated their lower rectus abdomini muscles (P < .05) and right internal
oblique muscles significantly more than did the LBP group (P < .05), whereas the
LBP group activated their left lateral erector spinae and both lumbar multifidi
sites significantly more than did the control group (P < .05). CONCLUSIONS: The
activation amplitudes of the anterior muscle sites were lower for participants
with LBP, whereas the posterior sites were activated to higher amplitudes than in
the control group. Although most muscles responded to the subphases indicating
muscle synergies, the group by muscle interactions for the right internal oblique
and lateral erector spinae show that the differences between groups were not
systematic. These results describe neuromuscular alterations in persons between
50-80 years with LBP that can be used for developing subject-specific management
related to maintaining spinal stability.
CI - Copyright (c) 2011 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS