Article

Motor control studies have shown that when walking is performed while resisting a
perturbation applied to the lower limb, the muscle activation pattern can be
temporarily modified. The objective of the present study is to validate if such
an approach, targeting the ankle, could specifically promote an increased
activation of the ankle dorsiflexor muscles that are of key importance for the
rehabilitation of foot drop. METHODS: 12 adults, with no gait deficit, walked on
a treadmill for three periods of 5min: before, during and after exposure to a
torque perturbation applied by a robotized ankle-foot orthosis that tended to
plantarflex the ankle during the swing phase. Spatiotemporal gait parameters,
ankle and knee kinematics, and the electromyographic activity of five lower limb
muscle groups were recorded. RESULTS: The perturbation initially caused a
deviation of the ankle towards plantarflexion. This movement error was rapidly
reduced and associated with a large increase (78.2%; p<0.001) in tibialis
anterior (ankle dorsiflexor; TA) activation, specifically in the stance-to-swing
burst. This increase carried over to post-perturbation walking, gradually
disappearing over several strides. Interestingly, these aftereffects led to an
increase in peak ankle dorsiflexion of approximately 7 degrees during the swing
phase. CONCLUSIONS: Walking while resisting a torque perturbation applied at the
ankle during swing promotes an increase in TA muscle activation that carries over
after perturbation removal, leading to an increased ankle dorsiflexion. Training
based on this approach may have the potential of improving the gait of persons
with foot drop.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS