Adaptations in antagonist co-activation: Role in the repeated-bout effect

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dc.contributor.authorHight, Robert E.
dc.contributor.authorBeck, Travis
dc.contributor.authorBemben, Debra A.
dc.contributor.authorBlack, Christopher
dc.date.accessioned2018-02-02T00:58:35Z
dc.date.available2018-02-02T00:58:35Z
dc.date.issued2017-12-07
dc.description.abstractEccentric exercise results in an adaptation which attenuates muscle damage from subsequent exercise—termed the “repeated-bout effect (RBE).” Purpose: Study examined antagonist co-activation and motor-unit recruitment strategy, assessed via dEMG, concomitant to the RBE. Methods: Nine participants performed 5 sub-maximal isometric trapezoid (ramp-up, hold, ramp-down) contractions at force levels corresponding to 50% and 80% of maximal isometric strength (MVC). Surface EMG signals of the biceps brachii were decomposed into individual motor-unit action potential trains. The relationship between mean firing rate (MFR) of each motor-unit and its recruitment threshold (RT) was examined using linear regression. Eccentric exercise was then performed until biceps brachii MVC had decreased by ~40%. Surface EMG of the biceps and triceps were collected during eccentric exercise. MVC, range-of-motion (ROM), and delayed onset muscle soreness (DOMS) were measured 24-hours, 72-hours, and 1-week following eccentric exercise. Three weeks later all procedures were repeated. Results: Changes in MVC (-32±14% vs -25±10%; p = 0.034), ROM (-11% vs 6%; p = 0.01), and DOMS (31.0±19mm vs 19±12mm; p = 0.015) were attenuated following the second bout of exercise. Triceps EMG was reduced (16.8±9.5% vs. 12.6±7.2%; p = 0.03) during the second bout of eccentric exercise. The slope (-0.60±0.13 vs -0.70±0.18; p = 0.029) and y-intercept (46.5±8.3 vs 53.3±8.8; p = 0.020) of the MFR vs. RT relationship was altered during contractions at 80% of MVC prior to the second bout of eccentric exercise. No changes were observed at 50% of MVC. Conclusion: A reduction in antagonist co-activation during the second bout of eccentric exercise suggests less total force was required to move an identical external load. This finding is supported by the increased negative slope coefficient and an increased y-intercept of the linear relationship between RT and MFR.en_US
dc.description.peerreviewYesen_US
dc.description.sponsorshipFunded by University of Oklahoma Graduate College Robberson Grant.en_US
dc.identifier.citationHight RE, Beck TW, Bemben DA, Black CD (2017) Adaptations in antagonist co-activation: Role in the repeated-bout effect. PLoS ONE 12(12): e0189323. https://doi.org/10.1371/journal.pone.0189323en_US
dc.identifier.urihttps://hdl.handle.net/11244/54343
dc.languageen_USen_US
dc.relation.ispartofseriesPLoS One;12(12)
dc.relation.urihttps://doi.org/10.1371/journal.pone.0189323
dc.rightsAttribution 4.0 International*
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/*
dc.subjectHealth Sciences, Medicine and Surgery.en_US
dc.subject.keywordsElectromyography
dc.subject.keywordsElbow
dc.subject.keywordsTriceps
dc.subject.keywordsStrength training
dc.subject.keywordsMuscle contraction
dc.subject.keywordsSignal filtering
dc.subject.keywordsAction potentials
dc.subject.keywordsLinear regression analysis
dc.titleAdaptations in antagonist co-activation: Role in the repeated-bout effecten_US
dc.typeArticleen_US
ou.groupCollege of Arts and Sciences::Department of Health and Exercise Scienceen_US

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