The Journal of Physiological Sciences

, Volume 60, Issue 2, pp 143–150

Effects of repeated lengthening contractions on skeletal muscle adaptations in female rats

  • Mark E. T. Willems
  • Gerald R. Miller
  • Francoise D. Stauber
  • William T. Stauber
Original Paper

DOI: 10.1007/s12576-009-0078-y

Cite this article as:
Willems, M.E.T., Miller, G.R., Stauber, F.D. et al. J Physiol Sci (2010) 60: 143. doi:10.1007/s12576-009-0078-y

Abstract

We examined the adaptation of plantar flexor muscles of female rats to 6 weeks (5 days/week) of lengthening contractions. After repeated lengthening contractions, a decrease in myofiber area of gastrocnemius medialis (26%) was accompanied by an increase in extracellular matrix (ECM) (42%) and collagen content (30.9%) without changes in muscle mass. Decrease in myofiber area (13%) and muscle mass of soleus (19%) was associated with increased collagen content (28%) and ECM (15%). Relative number of soleus myofibers stained for fast myosin increased by 26%. For plantaris, increases in collagen content (32.3%), percent ECM (17%), and myofiber area (6%) were recorded. We also observed (1) increases (3.3%) in the collagen content of the Achilles tendon, (2) no change in the crosslink content of any of the tissues tested, and (3) no difference in the force-frequency relationship of the plantar flexor muscles. Substantial decreases in myofiber areas with increases in muscle connective tissue by 6 weeks of repeated lengthening contractions did not appear to result in isometric force loss.

Keywords

Training Myofiber area Collagen Force transmission 

Copyright information

© The Physiological Society of Japan and Springer 2010

Authors and Affiliations

  • Mark E. T. Willems
    • 1
    • 2
  • Gerald R. Miller
    • 1
  • Francoise D. Stauber
    • 1
  • William T. Stauber
    • 1
  1. 1.Department of Physiology and Pharmacology, Robert C. Byrd Health Sciences Center, School of MedicineWest Virginia UniversityMorgantownUSA
  2. 2.Faculty of Sport, Education and Social SciencesUniversity of ChichesterChichesterUK

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