Cited by 216Muscle Physiology and DisordersMuscle metabolism and nutritionGenetics and Physical Performance

Cluster analysis tests the importance of myogenic gene expression during myofiber hypertrophy in humans

Bamman, Marcas M., Petrella, John K., Kim, Jeong-su, Mayhew, David L., Cross, James M.·2007·Journal of Applied Physiology

Abstract

We applied K-means cluster analysis to test the hypothesis that muscle-specific factors known to modulate protein synthesis and satellite cell activity would be differentially expressed during progressive resistance training (PRT, 16 wk) in 66 human subjects experiencing extreme, modest, and failed myofiber hypertrophy. Muscle mRNA expression of IGF-I isoform Ea (IGF-IEa), mechanogrowth factor (MGF, IGF-IEc), myogenin, and MyoD were assessed in muscle biopsies collected at baseline (T1) and 24 h after the first (T2) and last (T3) loading bouts from previously untrained subjects clustered as extreme responders (Xtr, n=17), modest responders (Mod, n=32), and nonresponders (Non, n=17) based on mean myofiber hypertrophy. Myofiber growth averaged 2,475 microm2 in Xtr, 1,111 microm2 in Mod, and -16 microm2 in Non. Main training effects revealed increases in all transcripts (46-83%, P<0.005). For the entire cohort, IGF-IEa, MGF, and myogenin mRNAs were upregulated by T2 (P<0.05), while MyoD did not increase significantly until T3 (P<0.001). Within clusters, MGF and myogenin upregulation was robust in Xtr (126% and 65%) and Mod (73% and 41%) vs. no changes in Non. While significant in all clusters by T3, IGF-IEa increased most in Xtr (105%) and least in Non (44%). Although MyoD expression increased overall, no changes within clusters were detected. We reveal for the first time that MGF and myogenin transcripts are differentially expressed in subjects experiencing varying degrees of PRT-mediated myofiber hypertrophy. The data strongly suggest the load-mediated induction of these genes may initiate important actions necessary to promote myofiber growth during PRT, while the role of MyoD is less clear.

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Crossref · 10.1152/japplphysiol.00024.2007

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Authors
Bamman, M. M., Petrella, J. K., Kim, J.-S., Mayhew, D. L., & Cross, J. M.
Affiliations
University of Alabama at Birmingham (US)
Venue
Journal of Applied Physiology
Published
2007-06
Volume
102
Issue
6
Pages
2232-2239
ISSN
  • 0161-7567 (ISSN-L)
  • 8750-7587
  • 1522-1601
OpenAlex
W2116499762
Cited by
216
References
50
Citations by year
2026: 6 · 2025: 8 · 2024: 7 · 2023: 7 · 2022: 7 · 2021: 10 · 2020: 15 · 2019: 15 · 2018: 22 · 2017: 10 · 2016: 13 · 2015: 13 · 2014: 10 · 2013: 15 · 2012: 13
FWCI
4.08
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Applied Physiology (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • U.S. Department of Veterans Affairs
  • University of Alabama at Birmingham
  • National Institute on Aging (R01AG017896)
  • National Center for Research Resources (M01RR00032, M01RR000032)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetics and Physical Performance
Keywords
muscle fiber hypertrophy, progressive resistance training, myogenin, MyoD, satellite cells, muscle protein synthesis, gene expression
MeSH terms
Adult, Aged, Physical Exertion, Female, Gene Expression Regulation, Humans, Hypertrophy, Male, Middle Aged, Muscle Contraction, Muscle Proteins, Biomarkers, Gene Expression, Cluster Analysis, Muscle, Skeletal, Gene Expression Profiling

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