Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/24952
Appears in Collections:Faculty of Health Sciences and Sport Journal Articles
Peer Review Status: Refereed
Title: Reduced firing rates of high threshold motor units in response to eccentric overload
Authors: Balshaw, Tom
Pahar, Madhu
Chesham, Ross
Macgregor, Lewis James
Hunter, Angus
Contact Email: a.m.hunter1@stir.ac.uk
Keywords: Decomposed electromyography
lengthening contractions
MVC
Issue Date: 20-Jan-2017
Citation: Balshaw T, Pahar M, Chesham R, Macgregor LJ & Hunter A (2017) Reduced firing rates of high threshold motor units in response to eccentric overload, Physiological Reports, 5 (2), Art. No.: e13111.
Abstract: Acute responses of motor units were investigated during submaximal voluntary isometric tasks following eccentric overload (EO) and constant load (CL) knee extension resistance exercise. Ten healthy resistance-trained participants performed four experimental test sessions separated by 5 days over a 20 day period. Two sessions involved constant load and the other two used eccentric overload. EO and CL used both sessions for different target knee eccentric extension phases; one at 2 sec and the other at 4 sec. Maximal voluntary contractions (MVC) and isometric trapezoid efforts for 10 sec at 70% MVC were completed before and after each intervention and decomposed electromyography was used to measure motor unit firing rate. The firing rate of later recruited, high-threshold motor units declined following the 2-sec EO but was maintained following 2sec CL (P < 0.05), whereas MUFR for all motor units were maintained for both loading types following 4-sec extension phases. MVC and rate of force development where maintained following both EO and CL and 2 and 4 sec phases. This study demonstrates a slower firing rate of high-threshold motor units following fast eccentric overload while MVC was maintained. This suggests that there was a neuromuscular stimulus without cost to the force-generating capacity of the knee extensors. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
DOI Link: http://dx.doi.org/10.14814/phy2.13111
Rights: © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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