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Functional coupling of motor units is modulated during walking in human subjects

Halliday, D.M., Conway, B.A., Christensen, L.O.D., Hansen, N.L., Petersen, N.P. and Nielsen, J.B. (2003) Functional coupling of motor units is modulated during walking in human subjects. Journal of Neurophysiology, 89 (2). pp. 960-968. ISSN 0022-3077

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Time- and frequency-domain analysis of the coupling between pairs of electromyograms (EMG) recorded from leg muscles was investigated during walking in healthy human subjects. For two independent surface EMG signals from the tibialis anterior (TA) muscle, coupling estimated from coherence measurements was observed at frequencies 50 Hz, with identifiable peaks occurring in two frequency bands ranging approximately from 8 to 15 and 15 to 20 Hz. The coherence between TA recordings was greatest toward the end of swing, reduced in early swing, and largely absent in midswing. In time-domain estimates constructed from paired TA EMG recordings, a short-lasting central peak indicative of motor-unit synchronization was observed. This feature of motor-unit coupling was also reduced in mid swing. In paired recordings made among triceps surae, quadriceps, and hamstring muscles, a similar pattern of correlation to that for paired TA recordings was observed. However, no significant coupling was observed in recordings for which one EMG recording was made from an ankle flexor/extensor muscle and the other from a knee extensor/flexor muscle. These results demonstrate that for TA a modulation exists in the functional coupling of motor units recruited during swing. The data also indicate that human motoneurons belonging to different muscles are only weakly coupled during walking. This absence of widespread short-term synchronization between the activities of muscles of the leg may provide a basis for the highly adaptive nature of human gait patterns.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Electronics (York)
Depositing User: York RAE Import
Date Deposited: 17 Apr 2009 14:52
Last Modified: 17 Apr 2009 14:55
Published Version: http://dx.doi.org/10.1152/jn.00844.2002
Status: Published
Publisher: American Physiological Society
Identification Number: 10.1152/jn.00844.2002
URI: http://eprints.whiterose.ac.uk/id/eprint/6764

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