Reactive gait and postural adjustments following the first exposures to (un)expected stepdown

Journal article


AminiAghdam, S., Vielemeyer, J., Abel, R. and Muller, R. (2019). Reactive gait and postural adjustments following the first exposures to (un)expected stepdown. Journal of Biomechanics. 94.
AuthorsAminiAghdam, S., Vielemeyer, J., Abel, R. and Muller, R.
Abstract

This study evaluated the reactive biomechanical strategies associated with both upper- and lower-body (lead and trail limbs) following the first exposures to (un)expected stepdown at comfortable (1.22 ± 0.08 m/s) and fast (1.71 ± 0.11 m/s) walking velocities. Eleven healthy adults completed 34 trails per walking velocity over an 8-m, custom-built track with two forceplates embedded in its center. For the expected stepdown, the track was lowered by 0-, −10- and −20-cm from the site of the second forceplate, whereas the unexpected stepdown was created by camouflaging the second forceplate (−10-cm). Two-way repeated-measurement ANOVAs detected no velocity-related effects of stepdown on kinematic and kinetic parameters during lead limb stance-phase, and on the trail limb stepping kinematics. However, analyses of significant interactions revealed greater peak flexion angles across the trunk and the trail limb joints (hip, knee and ankle) in unexpected versus expected stepdown conditions at a faster walking velocity. The −10-cm unexpected stepdown (main effect) had a greater influence on locomotor behavior compared to expected conditions due mainly to the absence of predictive adjustments, reflected by a significant decrease in peak knee flexion, contact time and vertical impulse during stance-phase. Walking faster (main effect) was associated with an increase in hip peak flexion and net anteroposterior impulse, and a decrease in contact time and vertical impulse during stepdown. The trail limb, in response, swung forward faster, generating a larger and faster recovery step. However, such reactive stepping following unexpected stepdown was yet a sparse compensation for an unstable body configuration, assessed by significantly smaller step width and anteroposterior margin-of-stability at foot-contact in the first-recovery-step compared with expected conditions. These findings depict the impact of the expectedness of stepdown onset on modulation of global dynamic postural control for a successful accommodation of (un)expected surface elevation changes in young, healthy adults.

Year2019
JournalJournal of Biomechanics
Journal citation94
PublisherElsevier
ISSN0021-9290
Digital Object Identifier (DOI)doi:10.1016/j.jbiomech.2019.07.029
Publication dates
Online31 Jul 2019
Print20 Sep 2019
Publication process dates
Accepted21 Jul 2019
Deposited04 Nov 2019
Accepted author manuscript
License
CC BY-NC-ND 4.0
File Access Level
Open
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https://openresearch.lsbu.ac.uk/item/885x5

Accepted author manuscript

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