Quantitative and qualitative adaptations of muscle fibers to glucocorticoids

Marco Alessandro Minetto, Rizwan Qaisar, Valentina Agoni, Giovanna Motta, Emanuela Longa, Danilo Miotti, Maria Antonietta Pellegrino, Roberto Bottinelli

Research output: Contribution to journalArticlepeer-review


Introduction: The aim of this study was to understand the effects of short-term glucocorticoid administration in healthy subjects. Methods: Five healthy men received dexamethasone (8 mg/day) for 7 days. Vastus lateralis muscle biopsy and knee extension torque measurement were performed before and after administration. A large number of individual muscle fibers were dissected from the biopsy samples (pre-administration: n=165, post-administration: n=177). Results: Maximal knee extension torque increased after administration (∼13%), whereas both type 1 and type 2A fibers had decreased cross-sectional area (type 1: ∼11%, type 2A: ∼17%), myosin loss (type 1: ∼18%, type 2A: ∼32%), and loss of specific force (type 1: ∼24%, type 2A: ∼33%), which were preferential for fast fibers. Conclusion: Short-term dexamethasone administration in healthy subjects elicits quantitative and qualitative adaptations of muscle fibers that precede (and may predict) the clinical appearance of myopathy in glucocorticoid-treated subjects.

Original languageEnglish
Pages (from-to)631-639
Number of pages9
JournalMuscle and Nerve
Issue number4
Publication statusPublished - Oct 1 2015


  • Cross-sectional area
  • Maximal shortening velocity
  • Myosin
  • Specific force
  • Steroid myopathy

ASJC Scopus subject areas

  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)
  • Physiology
  • Medicine(all)


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