HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 95/3/1045    most recent 00665.2002v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 ISI Web of Science (34) Citing Articles via Google Scholar Google Scholar Articles by Houtman, C. J. Articles by Zwarts, M. J. Search for Related Content PubMed PubMed Citation Articles by Houtman, C. J. Articles by Zwarts, M. J.

Changes in muscle fiber conduction velocity indicate recruitment of distinct motor unit populations

Department of Clinical Neurophysiology, Institute of Neurology, University Medical Centre, 6500 HB Nijmegen, The Netherlands

Submitted 19 July 2002 ; accepted in final form 21 May 2003

To obtain more insight into the changes in mean muscle fiber conduction velocity (MFCV) during sustained isometric exercise at relatively low contraction levels, we performed an in-depth study of the human tibialis anterior muscle by using multichannel surface electromyogram. The results show an increase in MFCV after an initial decrease of MFCV at 30 or 40% maximum voluntary contraction in all of the five subjects studied. With a peak velocity analysis, we calculated the distribution of conduction velocities of action potentials in the bipolar electromyogram signal. It shows two populations of peak velocities occurring simultaneously halfway through the exercise. The MFCV pattern implies the recruitment of two different populations of motor units. Because of the lowering of MFCV of the first activated population of motor units, the newly recruited second population of motor units becomes visible. It is most likely that the MFCV pattern can be ascribed to the fatiguing of already recruited predominantly type I motor units, followed by the recruitment of fresh, predominantly type II, motor units.

tibialis anterior muscle; size principle; surface electromyography; peak velocity; muscle fatigue; maximum voluntary contraction

This article has been cited by other articles:

				V. J. Boucher Acoustic Correlates of Fatigue in Laryngeal Muscles: Findings for a Criterion-Based Prevention of Acquired Voice Pathologies J Speech Lang Hear Res, October 1, 2008; 51(5): 1161 - 1170. [Abstract] [Full Text] [PDF]

				S. Banzet, N. Koulmann, N. Simler, O. Birot, H. Sanchez, R. Chapot, A. Peinnequin, and X. Bigard Fibre-type specificity of interleukin-6 gene transcription during muscle contraction in rat: association with calcineurin activity J. Physiol., August 1, 2005; 566(3): 839 - 847. [Abstract] [Full Text] [PDF]

				M. Gazzoni, F. Camelia, and D. Farina Conduction Velocity of Quiescent Muscle Fibers Decreases During Sustained Contraction J Neurophysiol, July 1, 2005; 94(1): 387 - 394. [Abstract] [Full Text] [PDF]

				D. Farina, M. Gazzoni, and F. Camelia Conduction velocity of low-threshold motor units during ischemic contractions performed with surface EMG feedback J Appl Physiol, April 1, 2005; 98(4): 1487 - 1494. [Abstract] [Full Text] [PDF]

				D. Farina, L. Arendt-Nielsen, and T. Graven-Nielsen Spike-triggered average torque and muscle fiber conduction velocity of low-threshold motor units following submaximal endurance contractions J Appl Physiol, April 1, 2005; 98(4): 1495 - 1502. [Abstract] [Full Text] [PDF]