Within-step modulation of leg muscles activity by afferent feedback in human walking

Richard af Klint, Jens Bo Nielsen, Jonathan D. Cole, Thomas Sinkjær, Michael James Grey

    39 Citationer (Scopus)

    Abstract

    To maintain smooth and efficient gait the motor system must adjust for changes in the ground on a step-to-step basis. In the present study we investigated the role of sensory feedback as 19 able-bodied human subjects walked over a platform that mimicked an uneven supporting surface. Triceps surae muscle activation was assessed during stance as the platform was set to different inclinations (+/-3 degrees , +/-2 degrees and 0 degrees rotation in a parasagittal plane about the ankle). Normalised triceps surae muscle activity was significantly increased when the platform was inclined (2 degrees : 0.153+/-0.051; 3 degrees : 0.156+/-0.053) and significantly decreased when the platform was declined (-3 degrees : 0.133+/-0.048; -2 degrees : 0.132+/-0.049) compared with level walking (0.141+/-0.048) for the able-bodied subjects. A similar experiment was performed with a subject who lacked proprioception and touch sensation from the neck down. In contrast with healthy subjects, muscle activation changes were observed in the deafferented subject. Our results demonstrate that the ability to compensate for small irregularities in the ground surface relies on automatic within-step sensory feedback regulation rather than conscious predictive control.
    OriginalsprogEngelsk
    TidsskriftJournal of Physiology
    Vol/bind586
    Udgave nummer19
    Sider (fra-til)4643-4648
    Antal sider6
    ISSN0022-3751
    DOI
    StatusUdgivet - 2008

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