Effects of chronic exercise during aging on muscle and end-plate morphology in rats

Charles L Stebbins, E. Schultz, R. T. Smith, E. L. Smith

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Terminal sprouting, myofiber atrophy, and fiber type changes were studied in soleus and distal gastrocnemius muscles of 21- and 26-mo-old rats and in rats who performed treadmill running from 21 to 26 mo. End-plate structure and muscle fiber types were demonstrated by staining for acetylcholinesterase and myosin ATPase activity. Terminal sprouting was expressed as the percentage of end plates with growth configurations. Fiber atrophy was assessed as percentage of small-diameter fibers. In all three groups, the percentage of small-diameter fibers was significantly smaller and the percentage of growth configurations significantly larger in the soleus than in the gastrocnemius. The exercised-soleus group had a significantly higher percentage of growth configuration than the 26-mo controls, which had a higher percentage than the 21-mo controls. Percentages among gastrocnemius groups were not different. Fiber type was similar among gastrocnemius groups. However, the exercised-soleus had significantly more slow-twitch fibers than the controls. These data suggest that the soleus responds differently to chronic exercise during aging than does the gastrocnemius.

Original languageEnglish (US)
Pages (from-to)45-51
Number of pages7
JournalJournal of Applied Physiology
Issue number1
StatePublished - 1985
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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