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Contraction speed and type influences rapid utilisation of available muscle force: neural and contractile mechanisms

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posted on 06.11.2018, 08:52 authored by Neale A. Tillin, Matthew PainMatthew Pain, Jonathan FollandJonathan Folland
This study investigated the influence of contraction speed and type on the human ability to rapidly increase torque and utilise the available maximum voluntary torque (MVT) as well as the neuromuscular mechanisms underpinning any effects. Fifteen young, healthy males completed explosive-voluntary knee-extensions in five conditions: isometric (ISO), and both concentric and eccentric at two constant accelerations of 500°.s-2 (CONSLOW and ECCSLOW) and 2000°.s-2 (CONFAST and ECCFAST). Explosive torque and quadriceps EMG were recorded every 25 ms up to 150 ms from their respective onsets and normalised to the available MVT and EMG at MVT, respectively, specific to that joint angle and velocity. Neural efficacy (explosive Voluntary:Evoked octet torque) was also measured, and torque data were entered into a Hill-type muscle model to estimate muscle performance. Explosive torques normalised to MVT (and normalised muscle forces) were greatest in the concentric, followed by isometric, and eccentric conditions; and in the fast compared with slow speeds within the same contraction type (CONFAST>CONSLOW>ISO, and ECCFAST>ECCSLOW). Normalised explosive-phase EMG and neural efficacy were greatest in concentric, followed by isometric and eccentric conditions, but were similar for fast and slow contractions of the same type. Thus, distinct neuromuscular activation appeared to explain the effect of contraction type but not speed on normalised explosive torque, suggesting the speed effect is an intrinsic contractile property. These results provide novel evidence that the ability to rapidly increase torque/force and utilise the available MVT is influenced by both contraction type and speed, due to neural and contractile mechanisms, respectively.

Funding

The work was funded by the affiliating institutions (University of Roehampton and Loughborough University).

History

School

  • Sport, Exercise and Health Sciences

Published in

Journal of Experimental Biology

Volume

221

Issue

24

Citation

TILLIN, N.A., PAIN, M.T.G. and FOLLAND, J.P., 2018. Contraction speed and type influences rapid utilisation of available muscle force: neural and contractile mechanisms. Journal of Experimental Biology, 221 (24), jeb193367.

Publisher

The Company of Biologists © The Authors

Version

AM (Accepted Manuscript)

Publisher statement

This paper was accepted for publication in the journal Journal of Experimental Biology and the definitive published version is available at https://doi.org/10.1242/jeb.193367

Acceptance date

15/10/2018

Publication date

2018-12-10

Copyright date

2018

ISSN

0022-0949

eISSN

1477-9145

Language

en

Location

England

Article number

jeb193367