Muscle fiber type grouping does not change in response to prolonged resistance exercise training in healthy older men

Autor: Dominika Kraková, Andrew M. Holwerda, Milan W. Betz, Kaleen M. Lavin, Marcas M. Bamman, Luc J.C. van Loon, Lex B. Verdijk, Tim Snijders
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Experimental Gerontology, Vol 173, Iss , Pp 112083- (2023)
Druh dokumentu: article
ISSN: 1873-6815
DOI: 10.1016/j.exger.2023.112083
Popis: Background: Ageing of skeletal muscle is characterized in some by muscle fiber type grouping due to denervation-reinnervation cycles, but the severity of fiber type grouping varies widely across individuals of the same chronological age. It remains unknown whether fiber type grouping is associated with lower muscle mass and/or reduced physical function in elderly. Therefore, we assessed the relationship between fiber type grouping and indices of muscle mass and physical function in older adults. In addition, we assessed whether fiber type grouping is affected by prolonged resistance training in older adults. Methods: Twenty young (21 ± 2 y) and twenty older (70 ± 4 y) healthy men participated in the present study. Body composition (DXA-scan), quadriceps cross-sectional area (CT-scan) and muscle strength (1RM) were assessed at baseline (young and old) and following 12 weeks of resistance training (old only). Percutaneous skeletal muscle biopsies from the vastus lateralis were collected at baseline (young and old) and following exercise training (old only). Immunohistochemical analyses were performed to evaluate type I and type II muscle fiber distribution, size, myonuclear content and grouping. Results: At baseline, type II fibers were significantly (P
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