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

Richard af Klint, Jens Bo Nielsen, Jonathan Cole, Thomas Sinkjaer, Michael J Grey

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42 Citations (Scopus)


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 deg, +/-2 deg and 0 deg rotation in a parasagittal plane about the ankle). Normalized triceps surae muscle activity was significantly increased when the platform was inclined (2 deg: 0.153 +/- 0.051; 3 deg: 0.156 +/- 0.053) and significantly decreased when the platform was declined (-3 deg: 0.133 +/- 0.048; -2 deg: 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, no 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.

Original languageEnglish
Pages (from-to)4643-4648
Number of pages6
JournalThe Journal of Physiology
Issue number19
Publication statusPublished - Oct 2008

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