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Myogenic, matrix, and growth factor mRNA expression in human skeletal muscle: Effect of contraction intensity and feeding

Authors

  • Jakob Agergaard MSc,

    Corresponding author
    1. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
    • Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
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  • Søren Reitelseder PhD,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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  • Troels G. Pedersen MSc,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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  • Simon Doessing MD, PhD,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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  • Peter Schjerling PhD,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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  • Henning Langberg PT, PhD,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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  • Benjamin F. Miller PhD,

    1. Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado, USA
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  • Per Aagaard PhD,

    1. Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
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  • Michael Kjær MD, PhD,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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  • Lars Holm PhD

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark
    2. Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark
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Correspondence to: J. Agergaard; E-mail: jakobagergaard@hotmail.com

Abstract

Introduction: We examined short-term (3-hour) and long-term (12-week) training effects after heavy load [HL; 70% 1RM] and light load (LL; 16% 1RM) exercise. Methods: mRNA expression of genes involved in skeletal muscle remodeling were analyzed and muscle activity (EMG measurements) was measured. Results: Relative muscle activity differed between HL and LL resistance exercise, whereas median power frequency was even, suggesting an equal muscle-fiber-type recruitment distribution. mRNA expression of Myf6, myogenin, and p21 was mostly increased, and myostatin was mostly depressed by HL resistance exercise. No major differences were seen in atrophy-related genes between HL and LL resistance exercise. No changes were seen over 12-week training for any of the targets. Conclusions: Resistance exercise at LL and HL elevated the expression of genes involved in skeletal muscle hypertrophy, although the greatest response was from HL. However, no long-term effect from either LL or HL resistance exercise was seen on basal levels of the mRNA targets. Muscle Nerve 47: 748–759, 2013

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