Long-term high-level exercise promotes muscle reinnervation with age

Simone Mosole, Ugo Carraro, Helmut Kern, Stefan Loefler, Hannah Fruhmann, Michael Vogelauer, Samantha Burggraf, Winfried Mayr, Matthias Krenn, Tatjana Paternostro-Sluga, Dusan Hamar, Jan Cvecka, Milan Sedliak, Veronika Tirpakova, Nejc Sarabon, Antonio Musarò, Marco Sandri, Feliciano Protasi, Alessandra Nori, Amber PondSandra Zampieri

Research output: Contribution to journalArticlepeer-review


The histologic features of aging muscle suggest that denervation contributes to atrophy, that immobility accelerates the process, and that routine exercise may protect against loss of motor units and muscle tissue. Here, we compared muscle biopsies from sedentary and physically active seniors and found that seniors with a long history of high-level recreational activity up to the time of muscle biopsy had 1) lower loss of muscle strength versus young men (32% loss in physically active vs 51% loss in sedentary seniors); 2) fewer small angulated (denervated) myofibers; 3) a higher percentage of fiber-type groups (reinnervated muscle fibers) that were almost exclusive of the slow type; and 4) sparse normal-size muscle fibers coexpressing fast and slow myosin heavy chains, which is not compatible with exercise-driven muscle-type transformation. The biopsies from the old physically active seniors varied from sparse fiber-type groupings to almost fully transformed muscle, suggesting that coexpressing fibers appear to fill gaps. Altogether, the data show that long-term physical activity promotes reinnervation of muscle fibers and suggest that decades of high-level exercise allow the body to adapt to age-related denervation by saving otherwise lost muscle fibers through selective recruitment to slow motor units. These effects on size and structure of myofibers may delay functional decline in late aging.

Original languageEnglish
Pages (from-to)284-294
Number of pages11
JournalJournal of Neuropathology and Experimental Neurology
Issue number4
Publication statusPublished - 2014


  • Aging
  • Coexpression of fast and slow myosin heavy chains
  • Denervation and reinnervation
  • Fiber-type grouping
  • Human skeletal muscle
  • Recreational sport activity

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Clinical Neurology
  • Neurology
  • Cellular and Molecular Neuroscience


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