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Effects of ipsilateral and contralateral fatigue and muscle blood flow occlusion on the complexity of knee extensor torque output in humans

Pethick, Jamie, Winter, Samantha L., Burnley, Mark (2018) Effects of ipsilateral and contralateral fatigue and muscle blood flow occlusion on the complexity of knee extensor torque output in humans. Experimental Physiology, 103 (7). pp. 956-967. ISSN 0958-0670. (doi:10.1113/EP086960) (KAR id:66857)

Abstract

Neuromuscular fatigue reduces the temporal structure, or complexity, of torque output during muscular contractions. To determine whether the fatigue-induced loss of torque complexity could be accounted for by central or peripheral factors, nine healthy participants performed four experimental trials involving intermittent isometric contractions of the knee extensors at 50% of the maximal voluntary contraction (MVC) torque. These trials involved: 1) two bouts of contractions to failure using the right leg separated by 3 min recovery (IPS); 2) the same protocol but with cuff occlusion during the 3-min recovery (IPS-OCC); 3) contractions of the left leg to failure, followed 1 min later by contractions of the right leg to failure (CONT); and 4) the same protocol but with cuff occlusion applied to the left leg throughout both the recovery period and right leg contractions (CONT-OCC). Supramaximal electrical stimulation during MVCs was used to determine the degree of central and peripheral fatigue, whilst complexity was determined using Approximate Entropy (ApEn) and Detrended Fluctuation Analysis ? exponent (DFA ?). Neuromuscular fatigue was consistently associated with a loss of torque complexity in all conditions (e.g., IPS bout 1 ApEn from [mean {plus minus} SD]: 0.46 {plus minus} 0.14 to 0.12 {plus minus} 0.06 [P < 0.001]). In IPS-OCC, occlusion abolished the recovery from fatigue and torque complexity remained at the values observed at task failure in the preceding bout (IPS-OCC bout 2, first minute: 0.14 {plus minus} 0.03, P < 0.001). Prior contralateral contractions, with or without blood flow occlusion, had no effect on torque complexity.

Item Type: Article
DOI/Identification number: 10.1113/EP086960
Uncontrolled keywords: central and peripheral fatigue, fractal scaling, non‐linear dynamics
Divisions: Divisions > Division of Natural Sciences > Sport and Exercise Sciences
Depositing User: Mark Burnley
Date Deposited: 26 Apr 2018 13:39 UTC
Last Modified: 16 Feb 2021 13:54 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/66857 (The current URI for this page, for reference purposes)
Winter, Samantha L.: https://orcid.org/0000-0001-7450-1105
Burnley, Mark: https://orcid.org/0000-0003-3407-561X
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