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dc.contributor.authorGejl, Kasper Degn
dc.contributor.authorHvid, Lars G.
dc.contributor.authorAndersson, Erik P.
dc.contributor.authorJensen, Rasmus
dc.contributor.authorHolmberg, Hans-Christer
dc.contributor.authorØrtenblad, Niels
dc.date.accessioned2021-10-21T07:50:49Z
dc.date.available2021-10-21T07:50:49Z
dc.date.issued2021-06-16
dc.description.abstract<i>Introduction</i>: Little is known about potential differences in contractile properties of muscle fibers of the same type in arms and legs. Accordingly, the present study was designed to compare the force-generating capacity and Ca<sup>2+</sup> sensitivity of fibers from arm and leg muscles of highly trained cross-country skiers.<br><br> <i>Method</i>: Single muscle fibers of <i>m. vastus lateralis</i> and <i>m. triceps brachii</i> of eight highly trained cross-country skiers were analyzed with respect to maximal Ca<sup>2+</sup>-activated force, specific force and Ca<sup>2+</sup> sensitivity.<br><br> <i>Result</i>: The maximal Ca<sup>2+</sup>-activated force was greater for myosin heavy chain (MHC) II than MHC I fibers in both the arm (+62%, <i>P</i> < 0.001) and leg muscle (+77%, <i>P</i> < 0.001), with no differences between limbs for each MHC isoform. In addition, the specific force of MHC II fibers was higher than that of MHC I fibers in both arms (+41%, <i>P</i> = 0.002) and legs (+95%, <i>P</i> < 0.001). The specific force of MHC II fibers was the same in both limbs, whereas MHC I fibers from the <i>m. triceps brachii</i> were, on average, 39% stronger than fibers of the same type from the <i>m. vastus lateralis</i> (<i>P</i> = 0.003). pCa<sub>50</sub> was not different between MHC I and II fibers in neither arms nor legs, but the MHC I fibers of <i>m. triceps brachii</i> demonstrated higher Ca<sup>2+</sup> sensitivity than fibers of the same type from <i>m. vastus lateralis</i> (<i>P</i> = 0.007).<br><br> <i>Conclusion</i>: Comparison of muscles in limbs equally well trained revealed that MHC I fibers in the arm muscle exhibited a higher specific force-generating capacity and greater Ca<sup>2+</sup> sensitivity than the same type of fiber in the leg, with no such difference in the case of MHC II fibers. These distinct differences in the properties of fibers of the same type in equally well-trained muscles open new perspectives in muscle physiology.en_US
dc.identifier.citationHvid, Andersson, Jensen, Holmberg, Ørtenblad. Contractile Properties of MHC I and II Fibers From Highly Trained Arm and Leg Muscles of Cross-Country Skiers. Frontiers in Physiology. 2021en_US
dc.identifier.cristinIDFRIDAID 1927792
dc.identifier.doi10.3389/fphys.2021.682943
dc.identifier.issn1664-042X
dc.identifier.urihttps://hdl.handle.net/10037/22799
dc.language.isoengen_US
dc.publisherFrontiers Mediaen_US
dc.relation.journalFrontiers in Physiology
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2021 The Author(s)en_US
dc.subjectVDP::Medical disciplines: 700::Sports medicine: 850en_US
dc.subjectVDP::Medisinske Fag: 700::Idrettsmedisinske fag: 850en_US
dc.titleContractile Properties of MHC I and II Fibers From Highly Trained Arm and Leg Muscles of Cross-Country Skiersen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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