Influence of intramuscular steroid receptor content and fiber capillarization on skeletal muscle hypertrophy

Kim Van Vossel, Julie Hardeel, Thibaux Van der Stede, Anneleen Weyns, Jan Boone, Silvia Salinas Blemker, Wim Derave, Eline Lievens*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

1 Citation (Scopus)

Abstract

Multiple intramuscular variables have been proposed to explain the high variability in resistance training induced muscle hypertrophy across humans. This study investigated if muscular androgen receptor (AR), estrogen receptor α (ERα) and β (ERβ) content and fiber capillarization are associated with fiber and whole-muscle hypertrophy after chronic resistance training. Male (n = 11) and female (n = 10) resistance training novices (22.1 ± 2.2 years) trained their knee extensors 3×/week for 10 weeks. Vastus lateralis biopsies were taken at baseline and post the training period to determine changes in fiber type specific cross-sectional area (CSA) and fiber capillarization by immunohistochemistry and, intramuscular AR, ERα and ERβ content by Western blotting. Vastus lateralis volume was quantified by MRI-based 3D segmentation. Vastus lateralis muscle volume significantly increased over the training period (+7.22%; range: −1.82 to +18.8%, p < 0.0001) but no changes occurred in all fiber (+1.64%; range: −21 to +34%, p = 0.869), type I fiber (+1.33%; range: −24 to +41%, p = 0.952) and type II fiber CSA (+2.19%; range: −23 to +29%, p = 0.838). However, wide inter-individual ranges were found. Resistance training increased the protein expression of ERα but not ERβ and AR, and the increase in ERα content was positively related to changes in fiber CSA. Only for the type II fibers, the baseline capillary-to-fiber-perimeter index was positively related to type II fiber hypertrophy but not to whole muscle responsiveness. In conclusion, an upregulation of ERα content and an adequate initial fiber capillarization may be contributing factors implicated in muscle fiber hypertrophy responsiveness after chronic resistance training.

Original languageEnglish
Article numbere14668
JournalScandinavian Journal of Medicine and Science in Sports
Volume34
Issue number6
Number of pages14
ISSN0905-7188
DOIs
Publication statusPublished - 2024

Bibliographical note

Publisher Copyright:
© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Keywords

  • androgen receptor
  • capillarization
  • estrogen receptor
  • muscle fiber hypertrophy
  • muscle hypertrophy

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