http://nnr.sagepub.com/content/27/3/230.abstract?etoc
Abstract
Background. Safe community ambulation requires the capacity to adapt gait to environmental changes on short notice. Reduced adaptability
may contribute to an increased risk for falls. Objective. This study investigated gait adaptability in community-dwelling persons poststroke and sought to understand some of the
mechanisms of reduced adaptability. Methods.
Participants were 25 poststroke persons (Functional Ambulation
Categories score 5) and 25 healthy controls of similar age.
During treadmill walking, 30 obstacles were
suddenly dropped in front of the affected leg or left leg of controls.
The participants
had to avoid the obstacle by either lengthening or
shortening the ongoing stride. The obstacle avoidance success rates were
determined. Electromyography activity of bilateral
biceps femoris, rectus femoris, tibialis anterior, and gastrocnemius
medialis
muscles was recorded as well as concomitant knee
and hip angle courses and spatial characteristics of the avoiding
stride.
Results. Poststroke persons demonstrated
markedly decreased obstacle avoidance success rates, most prominently
under time pressure.
They showed normal avoidance strategies but had
delayed and reduced electromyography responses, smaller joint angle
deviations
from unperturbed walking, and smaller horizontal
margins from the foot to the obstacle. Conclusions. Even in
persons who were only mildly affected by stroke, gait adaptability may
be reduced, which may place them at risk
of falling. Delayed and decreased muscle responses
were identified as one possible mechanism with diminished ability to
adapt
the length of the avoiding stride. Rehabilitation
interventions could focus on these impairments.
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