Article

The energy cost of walking could be attributed to energy related to the walking
movement and energy related to balance control. In order to differentiate between
both components we investigated the energy cost of walking an enforced step
pattern, thereby perturbing balance while the walking movement is preserved. Nine
healthy subjects walked three times at comfortable walking speed on an
instrumented treadmill. The first trial consisted of unconstrained walking. In
the next two trials, subject walked while following a step pattern projected on
the treadmill. The steps projected were either composed of the averaged step
characteristics (periodic trial), or were an exact copy including the variability
of the steps taken while walking unconstrained (variable trial). Metabolic energy
cost was assessed and center of pressure profiles were analyzed to determine task
performance, and to gain insight into the balance control strategies applied.
Results showed that the metabolic energy cost was significantly higher in both
the periodic and variable trial (8% and 13%, respectively) compared to
unconstrained walking. The variation in center of pressure trajectories during
single limb support was higher when a gait pattern was enforced, indicating a
more active ankle strategy. The increased metabolic energy cost could originate
from increased preparatory muscle activation to ensure proper foot placement and
a more active ankle strategy to control for lateral balance. These results entail
that metabolic energy cost of walking can be influenced significantly by control
strategies that do not necessary alter global gait characteristics.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS