title: Long-term high-level exercise promotes muscle reinnervation with age.
abstract: 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.
authors.affiliation: From the Laboratory of Translation Myology, Department of Biomedical Sciences, University of Padua, Padua, Italy (SM, UC, AN, SZ); Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria (HK, SL, HF, SB, SZ); Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria (HK, MV); Center of Biomedical Engineering and Physics, Medical University of Vienna, Vienna, Austria (WM, MK); Department of Physical Medicine and Rehabilitation, Medical University of Vienna, Vienna, Austria (TP-S); Faculty of Physical Education and Sport, Comenius University, Bratislava, Slovakia (DH, JC, MSedliak, VT); Science and Research Centre, Institute for Kinesilogical Research, University of Primorska, Koper, Slovenia (NS); DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome, Italy (AM); Venetian Institute of Molecular Medicine, Dulbecco Telethon Institute, and Department of Biomedical Science, University of Padua, Padua, Italy (MSandri); CeSI-Center for Research on Aging, and DNI-Department of Neuroscience and Imaging, University G. d'Annunzio of Chieti, Chieti, Italy (FP); and Anatomy Department, Southern Illinois University School of Medicine, Carbondale, Illinois (AP).
authors.forename: Simone
authors.initials: S
authors.lastname: Mosole
authors.forename: Ugo
authors.initials: U
authors.lastname: Carraro
authors.forename: Helmut
authors.initials: H
authors.lastname: Kern
authors.forename: Stefan
authors.initials: S
authors.lastname: Loefler
authors.forename: Hannah
authors.initials: H
authors.lastname: Fruhmann
authors.forename: Michael
authors.initials: M
authors.lastname: Vogelauer
authors.forename: Samantha
authors.initials: S
authors.lastname: Burggraf
authors.forename: Winfried
authors.initials: W
authors.lastname: Mayr
authors.forename: Matthias
authors.initials: M
authors.lastname: Krenn
authors.forename: Tatjana
authors.initials: T
authors.lastname: Paternostro-Sluga
authors.forename: Dusan
authors.initials: D
authors.lastname: Hamar
authors.forename: Jan
authors.initials: J
authors.lastname: Cvecka
authors.forename: Milan
authors.initials: M
authors.lastname: Sedliak
authors.forename: Veronika
authors.initials: V
authors.lastname: Tirpakova
authors.forename: Nejc
authors.initials: N
authors.lastname: Sarabon
authors.forename: Antonio
authors.initials: A
authors.lastname: Musarò
authors.forename: Marco
authors.initials: M
authors.lastname: Sandri
authors.forename: Feliciano
authors.initials: F
authors.lastname: Protasi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Nori
authors.forename: Amber
authors.initials: A
authors.lastname: Pond
authors.forename: Sandra
authors.initials: S
authors.lastname: Zampieri
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001706:Biopsy; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007797:Laminin / Q000378:metabolism; D008297:Male; D009043:Motor Activity; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018995:Myosin Heavy Chains / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D009416:Nerve Regeneration / Q000502:physiology; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D052097:Quadriceps Muscle / Q000294:innervation*; D055815:Young Adult
chemical_list: D007797:Laminin; D018994:Myosin Light Chains; D019006:Neural Cell Adhesion Molecules; D018995:Myosin Heavy Chains