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This Article Full Text Full Text (PDF) All Versions of this Article: 569/3/873    most recent jphysiol.2005.094516v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bamford, J. A. Articles by Mushahwar, V. K. Search for Related Content PubMed PubMed Citation Articles by Bamford, J. A. Articles by Mushahwar, V. K.

¹ Centre for Neuroscience, Faculty of Medicine and Dentistry
² Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation
³ Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada

Intraspinal microstimulation (ISMS), a novel rehabilitative therapy consisting of stimulation through fine, hair-like microwires targeted at the ventral spinal cord, has been proposed for restoring standing and walking following spinal cord injury. This study compared muscle recruitment characteristics of ISMS with those produced by peripheral nerve cuff stimulation (NCS). Thirty-three minutes of either ISMS or NCS at 1, 20 or 50 s^–1 and 1.2 x threshold (T) amplitude depleted glycogen from muscle fibres of vastus lateralis and rectus femoris. ISMS and NCS were also carried out at 20 s^–1 and 3.0T. Muscle serial sections were stained for glycogen and for myosin heavy chain (MHC)-based fibre types using a panel of monoclonal antibodies. The results of this study show that ISMS recruited fatigue-resistant (FR) fibres at 2.9, 1.9, 1.7 and 2.5 times their relative MHC content at 1, 20 and 50 s^–1 1.2T and 20 s^–1 3.0T, respectively. In contrast, NCS recruited FR fibres at 1.2, 1.0, 2.1 and 0.0 times their MHC content at 1, 20 and 50 s^–1 1.2T and 20 s^–1 3.0T, respectively. The proportion of FR fibres recruited by ISMS and NCS was significantly different in the 20 s^–1 3.0T condition (P < 0.0001). We also report that force recruitment curves were 4.9-fold less steep (P < 0.019) for ISMS than NCS. The findings of this study provide evidence for the efficacy of ISMS and further our understanding of muscle recruitment properties of this novel rehabilitative therapy.

(Received 11 July 2005; accepted after revision 18 October 2005; first published online 20 October 2005)
Corresponding author V. Mushahwar: Centre for Neuroscience and Department of Biomedical Engineering, Room 503, Heritage Medical Research Centre, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada. Email: vivian.mushahwar{at}ualberta.ca

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