Article

The mechanical efficiency of stepping to recover balance can be expressed by a
biomechanical model that includes the trunk inclination angle and the angle of
the leg at the instant of stepping-foot contact. The aim of the present study was
to test the hypothesis that this model would accurately predict the
successfulness of recovery attempts (recovery vs. falls) following large backward
perturbations. Ten young participants were exposed to a series of 12 very large
postural perturbations in the backward direction by means of a support-surface
translation. At the instant of stepping-foot contact, we calculated the trunk
inclination angle and the angle of the stepping leg with the vertical. Reaction
time, step duration, step velocity and step length were also determined. A
logistic regression analysis revealed that the model with leg and trunk
inclination angles accurately predicted successful recovery, with a more forward
tilted trunk and a further backward positioned leg increasing the probability of
success. The set of spatiotemporal step variables was significantly less
predictive. Over the course of the experiment, participants gradually became more
successful in recovering balance, which coincided with an increase in leg but not
in trunk angles. In conclusion, the body configuration at the instant of first
stepping-foot contact accurately predicted successful balance recovery after a
backward postural perturbation. Given the observation that participants improved
their performance by increasing their leg angles, which suggests that it may be
easier to improve this variable, compared to the trunk angle, by exercise
interventions.
CI - Copyright A(c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS