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Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship?

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journal contribution
posted on 03.08.2017, 10:08 by Marcel Bahia Lanza, Tom BalshawTom Balshaw, Jonathan FollandJonathan Folland
The influence of joint angle on knee extensor neuromuscular activation is unclear due in part due to the diversity of surface electromyography (sEMG) and/or interpolated twitch technique (ITT) methods employed. The aim of the study was to compare neuromuscular activation, using rigorous contemporary sEMG and ITT procedures, during isometric maximal voluntary contractions (iMVC) of the quadriceps femoris (Q) at different knee-joint angles and examine if activation contributes to the angle-torque relationship. Sixteen healthy active males completed two familiarization sessions and two experimental sessions of isometric knee extension and knee flexion contractions. The experimental sessions included the following at each of four joint angles (25°, 50°, 80° and 106°): iMVCs (with and without superimposed evoked doublets); submaximal contractions with superimposed doublets; evoked twitch and doublet contractions whilst voluntarily passive and knee flexion iMVC at the same knee joint positions. Absolute Q EMG was normalised to MMAX peak-to-peak amplitude and the doublet-voluntary torque relationship was used to calculate activation with the ITT (ACTITT ). Agonist activation, assessed with both normalised EMG and ACTITT , was reduced in the more extended compared to the more flexed positions (25 & 50 vs. 80 & 106°; P ≤ 0.016), whereas antagonist co-activation was greatest in the most flexed compared to the extended positions (106 vs. 25 & 50°; P ≤ 0.02). In conclusion, both agonist and antagonist activation differed with knee joint angle during knee extension iMVCs and thus both likely contribute to the knee extensor angle-torque relationship.

Funding

M.B.L. was supported by the Coordenacao de Aperfeicoamentode Pessoal de Nivel Superior (CAPES).

History

School

  • Sport, Exercise and Health Sciences

Published in

Experimental Physiology

Citation

LANZA, M.B., BALSHAW, T.G. and FOLLAND, J.P., 2017. Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship? Experimental Physiology, 102 (8), pp. 962–973.

Publisher

Wiley © The Authors. Experimental Physiology © The Physiological Society

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

05/06/2017

Publication date

2017

Notes

This is the peer reviewed version of the following article: LANZA, M.B., BALSHAW, T.G. and FOLLAND, J.P., 2017. Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship? Experimental Physiology, 102 (8), pp. 962–973, which has been published in final form at https://doi.org/10.1113/EP086343. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

ISSN

0958-0670

eISSN

1469-445X

Language

en

Location

England