Article

In people with lateralized disorders, such as stroke, Weight-Bearing
Asymmetry (WBA) is common.
It is associated with postural instability, however,
WBA is one of several abnormalities that may affect postural stability in these
disorders. Therefore, we investigated the isolated effects of WBA on dynamic
postural stability in healthy individuals. METHODS:
Ten young participants were
subjected to multidirectional stance perturbations by support surface
translations at three levels of WBA (0, 10 and 20% of body weight unloading of
one leg). The stepping threshold was determined iteratively for each condition
and in four perturbation directions (forward, backward, leftward and rightward).
The stepping threshold was defined as the highest perturbation intensity
recovered from with a feet-in-place response. The Margin of Stability (MOS) at
the stepping threshold was defined as the smallest distance between the vertical
projection of the Extrapolated Center of Mass (XCOM) and the edge of the base of
support. RESULTS: WBA decreased the stepping threshold (stability decreased) for
perturbations towards the loaded side (translations towards the unloaded side),
whereas it increased stepping thresholds for perturbations towards the unloaded
side. No significant effects of WBA were found on the MOS. WBA increased the
frequency of stepping with the unloaded leg upon forward and backward
perturbations. CONCLUSION: WBA increased dynamic stability towards the unloaded
leg following external balance perturbations and resulted in a greater
probability of stepping with this leg. Future studies are needed to evaluate the
functional significance of these WBA-related effects on postural stability in
people with lateralized disorders.
CI - Copyright (c) 2016 Elsevier B.V. All rights reserved.

Langue : ANGLAIS