The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size.

R. Nilwik, T. Snijders, M. Leenders, B.B. Groen, J. van Kranenburg, L.B. Verdijk, L.J.C. van Loon

Research output: Contribution to journalArticleAcademicpeer-review

95 Citations (Scopus)

Abstract

BACKGROUND: The loss of skeletal muscle mass with aging has been decline in muscle fiber number and muscle fiber size. OBJECTIVE: To what extent differences in leg muscle cross-sectional area (CSA) between and elderly men are attributed to differences in muscle fiber size. Quadriceps muscle CSA and type I and II muscle fiber size were measured healthy young (n=25; 23+/-1y) and older (n=26; 71+/-1y) men. older subjects performed 6 months of resistance type exercise training, which measurements were repeated. Differences in quadriceps muscle CSA compared with differences in type I and II muscle fiber size. RESULTS: CSA was substantially smaller in older versus young men (68+/-2 vs 80+/- respectively; P<0.001). Type II muscle fiber size was substantially the elderly vs the young (29%; P<0.001), with a tendency of smaller type fibers (P=0.052). Differences in type II muscle fiber size fully differences in quadriceps CSA between groups. Prolonged resistance type training in the elderly increased type II muscle fiber size by 24+/-8% explaining 100+/-3% of the increase in quadriceps muscle CSA (from 68+/- 74+/-2 cm(2)). CONCLUSION: Reduced muscle mass with aging is mainly smaller type II muscle fiber size and, as such, is unlikely accompanied substantial muscle fiber loss. In line, the increase in muscle mass prolonged resistance type exercise training can be attributed entirely specific type II muscle fiber hypertrophy.
Original languageEnglish
Pages (from-to)492-498
Number of pages7
JournalExperimental Gerontology
Volume48
Issue number5
DOIs
Publication statusPublished - May 2013

Keywords

  • Sarcopenia
  • Atrophy
  • Exercise training
  • Hypertrophy
  • Type II muscle fibers
  • SATELLITE CELL NUMBERS
  • OLDER MEN
  • PROTEIN SUPPLEMENTATION
  • RESISTANCE EXERCISE
  • STRENGTH
  • AGE
  • HYPERTROPHY
  • YOUNG
  • COEXPRESSION
  • ADAPTATIONS

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