Cited by 356Muscle Physiology and DisordersMuscle metabolism and nutritionSports Performance and Training

Efficacy of myonuclear addition may explain differential myofiber growth among resistance-trained young and older men and women

Petrella, John K., Kim, Jeong-su, Cross, James M., Kosek, David J., Bamman, Marcas M.·2006·American Journal of Physiology-Endocrinology and Metabolism

Abstract

Skeletal muscle stem (satellite) cells supporting growth/regeneration are thought to be activated and incorporated into growing myofibers by both endocrine and locally expressed autocrine/paracrine growth factors, the latter being load sensitive. We recently found that myofiber hypertrophy with resistance training is superior in young men (YM) vs. young women and older adults (Kosek DJ, Kim JS, Petrella JK, Cross JM, and Bamman MM. J Appl Physiol 101: 531-544, 2006). We hypothesized that the advanced myofiber hypertrophy in YM is facilitated by myonuclear addition in response to a milieu promoting stem cell activation. Twenty-six young (27.0 +/- 1 yr, 50% women) and 26 older (63.7 +/- 1 yr, 50% women) adults completed 16 wk of knee extensor resistance training. Vastus lateralis biopsies were obtained at baseline, 24 h after one bout, and after 16 wk. Muscle stem cells were identified immunohistochemically with anti-neural cell adhesion molecule (NCAM+). Muscle transcript levels of IGF-I and mechanogrowth factor (MGF) were determined by RT-PCR. Serum IGF-I, IGF-binding protein (IGFBP)-3, IGFBP-1, total and free testosterone, sex hormone-binding globulin (SHBG), and androstenedione were assessed by radioimmunoassay. Myofiber hypertrophy was twofold greater in YM vs. others, and only YM increased NCAM+ cells per 100 myofibers (49%) and myonuclei per fiber (19%) (P < 0.05). IGF-IEa mRNA was higher in young and increased acutely (29%) with summation by 16 wk (96%) (P < 0.05). MGF mRNA increased only in young after one bout (81%) and by 16 wk (85%) (P < 0.001). Circulating IGF-I was twofold higher in young, whereas IGFBP-1 was lowest in YM (P < 0.05). Among men, free testosterone was 59% higher in YM (P < 0.01). Myonuclear addition was most effectively accomplished in YM, which likely drove the superior growth.

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Crossref · 10.1152/ajpendo.00190.2006

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Authors
Petrella, J. K., Kim, J.-S., Cross, J. M., Kosek, D. J., & Bamman, M. M.
Affiliations
University of Alabama at Birmingham (US)
Venue
American Journal of Physiology-Endocrinology and Metabolism
Published
2006-11
Volume
291
Issue
5
Pages
E937-E946
ISSN
  • 0193-1849 (ISSN-L)
  • 1522-1555
OpenAlex
W2154326737
Cited by
356
References
61
Citations by year
2026: 4 · 2025: 5 · 2024: 8 · 2023: 15 · 2022: 24 · 2021: 15 · 2020: 18 · 2019: 22 · 2018: 24 · 2017: 17 · 2016: 28 · 2015: 22 · 2014: 20 · 2013: 16 · 2012: 25
FWCI
6.65
Type
journal article
Language
en
Open access
closed
Locations
  • American Journal of Physiology-Endocrinology and Metabolism (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • U.S. Department of Veterans Affairs
  • University of Alabama at Birmingham
  • National Institute on Aging (R01AG017896, R01 AG17896)
  • National Center for Research Resources (M01RR00032, M01RR000032)
  • NIH Clinical Center
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
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
Keywords
muscle fiber hypertrophy, resistance training, skeletal muscle stem cells, satellite cells, insulin-like growth factor I, IGFBP-1, IGFBP-3, free testosterone, sex differences, aging, vastus lateralis, CD56, androstenedione, sex hormone-binding globulin
MeSH terms
Adult, Aged, Aging, Androstenedione, Cell Nucleus, Female, Humans, Insulin-Like Growth Factor I, Male, Middle Aged, RNA, Messenger, Sex Characteristics, Sex Hormone-Binding Globulin, Testosterone, Exercise, Muscle, Skeletal, Insulin-Like Growth Factor Binding Protein 1, Insulin-Like Growth Factor Binding Protein 3, Neural Cell Adhesion Molecules, Satellite Cells, Skeletal Muscle, Cell Size

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