The specific force of single intact extensor digitorum longus and soleus mouse muscle fibers declines with aging

J Membr Biol. 2000 Dec 1;178(3):175-83. doi: 10.1007/s002320010025.


In the present study we measured, for the first time, the isometric specific force (SF, force normalized to cross sectional area) generated by single intact fibers from fast- (extensor digitorum longus, EDL) and slow-twitch (soleus) muscles from young adult (2-6), middle-aged (12-14) and old (20-24 month-old) mice. SF has also been measured in single intact flexor digitorum brevis fibers from young mice. Muscle fibers have been classified into fast- or slow-twitch based on the contraction kinetics. Maximum SF recorded in EDL and soleus fibers from young and middle-aged mice did not differ significantly. A significant age-dependent decline in maximum SF was recorded in EDL and soleus fibers from young or middle-aged to old mice. The SF was 377 +/- 18, 417 +/- 20 and 279 +/- 18 kPa for EDL fibers from young, middle-aged and old mice, respectively and 397 +/- 17, 405 +/- 24 and 320 +/- 33 kPa for soleus fibers from age-matched mice, respectively. The frequency needed to elicit maximum force in EDL and soleus fibers from middle-aged to old mice did not differ significantly. In conclusion, the specific force developed by both fast and slow-twitch single intact muscle fibers declines with aging and more significantly in the former.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aging / physiology*
  • Animals
  • Female
  • Isometric Contraction
  • Kinetics
  • Male
  • Mice
  • Mice, Inbred DBA
  • Muscle Contraction*
  • Muscle Development*
  • Muscle Fibers, Fast-Twitch / chemistry
  • Muscle Fibers, Fast-Twitch / physiology*
  • Muscle Fibers, Slow-Twitch / chemistry
  • Muscle Fibers, Slow-Twitch / physiology*
  • Muscle, Skeletal / growth & development*
  • Muscle, Skeletal / physiology
  • Myosin Heavy Chains / analysis
  • Protein Isoforms / analysis
  • Specific Pathogen-Free Organisms


  • Protein Isoforms
  • Myosin Heavy Chains