Article

Spontaneous respiration influences the body's center-of-mass when standing. We contend that the healthy postural control system actively adapts to respiration,
thereby minimizing its effect on postural sway. We therefore examined the
interaction between respiration and postural sway, as measured by
center-of-pressure (COP) oscillations, and quantified the extent to which this
interaction resulted in "posturo-respiratory synchronization." We hypothesized
that synchronization would be stronger in elderly subjects and those with stroke,
and when standing with eyes closed as compared to open, due to alterations in the
physiologic mechanisms that normally regulate postural sway. Twenty-five subjects
with chronic hemispheric infarction and 38 controls (50-80 years) stood on a
force platform for 3 min with eyes-open and 3 min with eyes-closed. Respiratory
flow and COP dynamics were simultaneously recorded. The dominant oscillatory mode
of respiration and the corresponding oscillatory modes of anterioposterior and
mediolateral COP dynamics were extracted using ensemble empirical mode
decomposition. The strength of posturo-respiratory synchronization was quantified
from the regularity of instantaneous phase shifts between extracted respiratory
and COP oscillations. Significant posturo-respiratory synchronization was only
present in the anterioposterior direction. The strength of synchronization
increased with age (p<0.01). Closing the eyes increased synchronization strength
in both groups (p=0.01), but more so in stroke patients (p=0.01). These
observations suggest that a control system actively regulates the effects of
respiration on sagittal-plane postural sway, particularly during eyes-open
standing. As evidenced by increased posturo-respiratory synchronization with
advanced age and central lesion, this novel metric may be used as a clinical
marker of altered postural control.
CI - Copyright (c) 2012 Elsevier B.V. All rights reserved.

Langue : ANGLAIS