title: Anticipatory kinematics and muscle activity preceding transitions from level-ground walking to stair ascent and descent.
abstract: The majority of fall-related accidents are during stair ambulation-occurring commonly at the top and bottom stairs of each flight, locations in which individuals are transitioning to stairs. Little is known about how individuals adjust their biomechanics in anticipation of walking-stair transitions. We identified the anticipatory stride mechanics of nine able-bodied individuals as they approached transitions from level ground walking to stair ascent and descent. Unlike prior investigations of stair ambulation, we analyzed two consecutive "anticipation" strides preceding the transitions strides to stairs, and tested a comprehensive set of kinematic and electromyographic (EMG) data from both the leading and trailing legs. Subjects completed ten trials of baseline overground walking and ten trials of walking to stair ascent and descent. Deviations relative to baseline were assessed. Significant changes in mechanics and EMG occurred in the earliest anticipation strides analyzed for both ascent and descent transitions. For stair descent, these changes were consistent with observed reductions in walking speed, which occurred in all anticipation strides tested. For stair ascent, subjects maintained their speed until the swing phase of the latest anticipation stride, and changes were found that would normally be observed for decreasing speed. Given the timing and nature of the observed changes, this study has implications for enhancing intent recognition systems and evaluating fall-prone or disabled individuals, by testing their abilities to sense upcoming transitions and decelerate during locomotion.
authors.affiliation: Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Peng
authors.affiliation: Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA; Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL 60611, USA. Electronic address: nfey@ricres.org.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Fey
authors.affiliation: Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA; Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Kuiken
authors.affiliation: Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA; Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Levi J
authors.initials: LJ
authors.lastname: Hargrove
mesh_terms: D000054:Acceleration; D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D008297:Male; D055595:Mechanical Phenomena; D009132:Muscles / Q000502:physiology*; D016138:Walking / Q000502:physiology*
keywords: Ambulation; Anticipation; Biomechanics; Electromyography; Gait; Kinematics; Stair transitions