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dc.contributor.authorBowtell, Jo
dc.contributor.authorAvenell, Gareth
dc.contributor.authorHunter, Steven P.
dc.contributor.authorMileva, Katya N.
dc.date.accessioned2014-11-12T17:06:18Z
dc.date.issued2013
dc.description.abstractWe investigated whether altered peripheral and/or corticospinal excitatory output and voluntary activation are implicated in hypohydration-induced reductions in muscle isometric and isokinetic (90°.s(-1)) strength. Nine male athletes completed two trials (hypohydrated, euhydrated) comprising 90 min cycling at 40°C, with body weight losses replaced in euhydrated trial. Peripheral nerve and transcranial magnetic stimulations were applied during voluntary contractions pre- and 40 min post-exercise to quantify voluntary activation and peripheral (M-wave) and corticospinal (motor evoked potential) evoked responses in m. vastus medialis. Both maximum isometric (-15.3±3.1 vs -5.4±3.5%) and isokinetic eccentric (-24.8±4.6 vs -7.3±7.2%) torque decreased to a greater extent in hypohydrated than euhydrated trials (p<0.05). Half relaxation time of the twitch evoked by peripheral nerve stimulation during maximal contractions increased after exercise in the hypohydrated (21.8±9.3%) but stayed constant in the euhydrated (1.6±10.7%; p = 0.017) condition. M-wave amplitude during maximum voluntary contraction increased after exercise in the heat in hypohydrated (10.7±18.0%) but decreased in euhydrated condition (-17.4±16.9%; p = 0.067). Neither peripheral nor cortical voluntary activation were significantly different between conditions. Motor evoked potential amplitude increased similarly in both conditions (hypohydrated: 25.7±28.5%; euhydrated: 52.9±33.5%) and was accompanied by lengthening of the cortical silent period in euhydrated but not hypohydrated condition (p = 0.019). Different neural strategies seem to be adopted to regulate neural drive in the two conditions, with increases in inhibitory input of either intracortical or corticospinal origin during the euhydrated trial. Such changes were absent in the hypohydrated condition, yet voluntary activation was similar to the euhydrated condition, perhaps due to smaller increases in excitatory drive rather than increased inhibition. Despite this maximal isometric and eccentric strength were impaired in the hypohydrated condition. The increase in peripheral muscle excitability evident in the hypohydrated condition was not sufficient to preserve performance in the face of reduced muscle contractility or impaired excitation-contraction coupling.en_GB
dc.identifier.citationVol. 8 (10), article e77004en_GB
dc.identifier.doi10.1371/journal.pone.0077004
dc.identifier.urihttp://hdl.handle.net/10871/15845
dc.language.isoenen_GB
dc.publisherPublic Library of Scienceen_GB
dc.relation.urlhttp://dx.doi.org/10.1371/journal.pone.0077004en_GB
dc.relation.urlhttp://www.ncbi.nlm.nih.gov/pubmed/24098574en_GB
dc.rightsThis article is published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_GB
dc.subjectAdulten_GB
dc.subjectAthletesen_GB
dc.subjectDehydrationen_GB
dc.subjectElectric Stimulationen_GB
dc.subjectElectromyographyen_GB
dc.subjectEvoked Potentials, Motoren_GB
dc.subjectExerciseen_GB
dc.subjectFluid Therapyen_GB
dc.subjectHumansen_GB
dc.subjectIsometric Contractionen_GB
dc.subjectMaleen_GB
dc.subjectMotor Cortexen_GB
dc.subjectMotor Neuronsen_GB
dc.subjectMuscle Fatigueen_GB
dc.subjectMuscle, Skeletalen_GB
dc.subjectSpinal Corden_GB
dc.subjectTorqueen_GB
dc.subjectTranscranial Magnetic Stimulationen_GB
dc.titleEffect of hypohydration on peripheral and corticospinal excitability and voluntary activationen_GB
dc.typeArticleen_GB
dc.date.available2014-11-12T17:06:18Z
exeter.place-of-publicationUnited States
dc.descriptionOpen Access journalen_GB
dc.descriptionPMCID: PMC3788753en_GB
dc.descriptionCopyright: © 2013 Bowtell et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_GB
dc.identifier.eissn1932-6203
dc.identifier.journalPLoS Oneen_GB


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