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Pflügers Archiv

, Volume 434, Issue 3, pp 246–253 | Cite as

Decline in isokinetic force with age: muscle cross-sectional area and specific force

  • S. A. Jubrias
  • I. R. Odderson
  • Peter C. Esselman
  • Kevin E. Conley
ORIGINAL ARTICLE

Abstract

 Humans produce less muscle force (F) as they age. However, the relationship between decreased force and muscle cross-sectional area (CSA) in older humans is not well documented. We examined changes in F and CSA to determine the relative contributions of muscle atrophy and specific force (F/CSA) to declining force production in aging humans. The proportions of myosin heavy chain (MHC) isoforms were characterized to assess whether this was related to changes in specific force with age. We measured the peak force of isokinetic knee extension in 57 males and females aged 23–80 years, and used magnetic resonance imaging to determine the contractile area of the quadriceps muscle. Analysis of MHC isoforms taken from biopsies of the vastus lateralis muscle showed no relation to specific force. F, CSA, and F/CSA decreased with age. Smaller CSA accounted for only about half of the 39% drop in force that occurred between ages 65–80 years. Specific force dropped about 1.5% per year in this age range, for a total decrease of 21%. Thus, quantitative changes in muscle (atrophy) are not sufficient to explain the strength loss associated with aging.

Key words MVC maximum voluntary contraction Myosin heavy chains Magnetic resonance imaging 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • S. A. Jubrias
    • 1
  • I. R. Odderson
    • 2
  • Peter C. Esselman
    • 2
  • Kevin E. Conley
    • 1
  1. 1.Department of Radiology, University of Washington Medical Center, Box 357115, Seattle WA 98195, USAUS
  2. 2.Department of Rehabilitation, University of Washington Medical Center, Box 356490, Seattle WA 98195, USAUS

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