Article

Falls during walking reflect susceptibility to balance loss and the individual's
capacity to recover stability. Balance can be recovered using either one step or
multiple steps but both responses are impaired with ageing. To investigate older
adults' (n=15, 72.5+/-4.8 yrs) recovery step control a tether-release procedure
was devised to induce unanticipated forward balance loss. Three-dimensional
position-time data combined with foot-ground reaction forces were used to measure
balance recovery. Dependent variables were; margin of stability (MoS) and
available response time (ART) for spatial and temporal balance measures in the
transverse and sagittal planes; lower limb joint angles and joint
negative/positive work; and spatio-temporal gait parameters. Relative to
multi-step responses, single-step recovery was more effective in maintaining
balance, indicated by greater MoS and longer ART. MoS in the sagittal plane
measure and ART in the transverse plane distinguished single step responses from
multiple steps. When MoS and ART were negative (<0), balance was not secured and
additional steps would be required to establish the new base of support for
balance recovery. Single-step responses demonstrated greater step length and
velocity and when the recovery foot landed, greater centre of mass downward
velocity. Single-step strategies also showed greater ankle dorsiflexion,
increased knee maximum flexion and more negative work at the ankle and knee.
Collectively these findings suggest that single-step responses are more effective
in forward balance recovery by directing falling momentum downward to be absorbed
as lower limb eccentric work.
CI - Copyright (c) 2015 Elsevier B.V. All rights reserved.

Langue : ANGLAIS