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

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

Research Abstract Table of Contents

Jump to the:

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

John K Petrella,Jeong-su Kim,James M Cross,David J Kosek,Marcas M Bamman,

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.

Efficacy of myonuclear addition may explain differential myofiber growth among resistance-trained young and older men and women. Publishing Authors By Initials

JK Petrella,JS Kim,JM Cross,DJ Kosek,MM Bamman,

For similar polycyclic compounds: steroids: androstanes: androstenes: androstenols: testosterone research abstracts see: polycyclic compounds: steroids: androstanes: androstenes: androstenols: testosterone research

PUBMED ID PMID:

MEDLINE DATE:

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

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: American journal of physiology. Endocrinology and

VOLUME: 291

Page Numbers: E937-46

Journal Abbreviation: Am. J. Physiol. Endocrinol. Me

ISSN: 0193-1849

DAY: 13

MONTH: 06

YEAR: 2006

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

Number of References:

LANGUAGE: eng

NlmUniqueID: 100901226

Efficacy of myonuclear addition may explain differential myofiber growth among resistance-trained young and older men and women. Keywords Mesh Terms:

KEYWORDS: Testosterone

MESH TERMS: metabolism

Chemical & Substance for Abstract: Efficacy of myonuclear addition may explain differential myofiber growth among resistance-trained young and older men and women. Information

Substance Name: Insulin-Like Growth Factor I

Registry Number: 67763-96-6

Grant and Affiliation Information for Efficacy of myonuclear addition may explain differential myofiber growth among resistance-trained young and older men and women.

AFFILIATION: Department of Physiology and Biophysics, The University of Alabama at Birmingham, Birmingham, AL 35294-0001, USA.

Country: United States

AGENCY: United States NIA

GRANT: R01-AG-17896

ACRONYM: AG

MEDLINETA: Am J Physiol Endocrinol Metab

REFSOURCE:

DATABASENAME:

ACCESSION NUMBER:

Number Hits: 0

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

• ANALYSIS OF COST KEEPING AS APPLIED TO MUNICIPAL MANAGEMENT OF STREET CLEANING.
• Causes and Consequences of Declining Muscle Power in Aging Adults and Strategies for Improvement: 354: 2:10 PM-2:40 PM.
• Efficacy of myonuclear addition may explain differential myofiber growth among resistance-trained young and older men and women.
• Load-mediated downregulation of myostatin mRNA is not sufficient to promote myofiber hypertrophy in humans: a cluster analysis.
• Modulation of the dystrophin-associated protein complex in response to resistance training in young and older men.
• Potent myofiber hypertrophy during resistance training in humans is associated with satellite cell-mediated myonuclear addition: a cluster analysis.
• Reply to dr. Heinemeier.
• The exercise dose response: key lessons from the past.