Abstract We investigated the influence of nociceptive stimulation on the accuracy of task execution and motor unit spike trains during low-force isometric contractions. Muscle pain was induced by infusion of hypertonic saline into the abductor digiti minimi muscle of 11 healthy men. Intramuscular EMG signals were recorded from the same muscle during four isometric contractions of 60-s duration at 10% of the maximal force (maximal voluntary contraction (MVC)) performed before injection (baseline), after injection of isotonic (control) or hypertonic saline (pain), and 15 min after pain was no longer reported. Each contraction was preceded by three 3-s ramp contractions from 0% to 10% MVC. The low-frequency oscillations of motor unit spike trains were analyzed by the first principal component of the low-pass filtered spike trains (first common component (FCC)), which represents the effective neural drive to the muscle. Pain decreased the accuracy of task performance (coefficient of variation (CoV) for force: baseline, 2.8 ± 1.8%, pain, 3.9 ± 1.8%; P < 0.05) and reduced motor unit discharge rates (11.6 ± 2.3 pulses per second (pps) vs. 10.7 ± 1.7 pps; P < 0.05). Motor unit recruitment thresholds (2.2 ± 1.2% MVC vs. 2.4 ± 1.6% MVC), interspike interval variability (18.4 ± 4.9% vs. 19.1 ± 5.4%), strength of motor unit short-term synchronization (common input strength (CIS) 1.02 ± 0.44 vs. 0.83 ± 0.22), and strength of common drive (0.47 ± 0.08 vs. 0.47 ± 0.06) did not change across conditions. The FCC signal was correlated with force ( R = 0.45 ± 0.06), and the CoV for FCC increased in the painful condition (5.69 ± 1.29% vs. 7.83 ± 2.61%; P < 0.05). These results indicate that nociceptive stimulation increased the low-frequency variability in synaptic input to motoneurons. motor unit common principal component interspike interval short-term synchronization common drive Copyright © 2012 the American Physiological Society « Previous | Next Article » Table of Contents This Article Published online before print November 2011 , doi: 10.​1152/​jn.​00304.​2011 AJP - JN Physiol February 2012 vol. 107 no. 3 958-965 » Abstract Free Full Text Free to you Full Text (PDF) Free to you All Versions of this Article: jn.00304.2011v1 107/3/958 most recent Classifications Article Services Email this article to a friend Alert me when this article is cited Alert me if a correction is posted Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Download to citation manager Citing Articles Load citing article information Citing articles via Web of Science Google Scholar Articles by Farina, D. Articles by Falla, D. PubMed PubMed citation Articles by Farina, D. Articles by Falla, D. Related Content Load related web page information Current Issue February 2012, 107 (3) Alert me to new issues of AJP - JN Physiol About the Journal Information for Authors Submit a Manuscript Ethical Policies AuthorChoice PubMed Central Policy Reprints and Permissions Advertising Press Copyright © 2012 the American Physiological Society Print ISSN: 0022-3077 Online ISSN: 1522-1598 var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); var pageTracker = _gat._getTracker("UA-2924550-1"); pageTracker._trackPageview();

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