Similar acute molecular responses to equivalent volumes of isometric, lengthening, or shortening mode resistance exercise

J Appl Physiol (1985). 2007 Jan;102(1):135-43. doi: 10.1152/japplphysiol.00776.2006. Epub 2006 Sep 28.


The present study was undertaken to test the hypothesis that the contraction mode of action [static-isometric (Iso), shortening-concentric (Con), or lengthening-eccentric (Ecc)] used to stress the muscle provides a differential mechanical stimulus eliciting greater or lesser degrees of anabolic response at the initiation of a resistance training program. We performed an acute resistance training study in which different groups of rodents completed four training sessions in either the Iso, Con, or Ecc mode of contraction under conditions of activation and movement specifically designed to elicit equivalent volumes of force accumulation. The results of this experiment indicate that the three modes of contraction produced nearly identical cell signaling, indicative of an anabolic response involving factors such as increased levels of mRNA for IGF-I, procollagen III alpha1, decreased myostatin mRNA, and increased total RNA concentration. The resulting profiles collectively provide evidence that pure mode of muscle action, in and of itself, does not appear to be a primary variable in determining the efficacy of increased loading paradigms with regard to the initiation of selected muscle anabolic responses.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Body Weight / physiology
  • Collagen Type III / metabolism
  • DNA / metabolism
  • Female
  • Insulin-Like Growth Factor I / metabolism
  • Isometric Contraction / physiology*
  • Metabolism / physiology
  • Muscle Contraction / physiology*
  • Muscle Proteins / metabolism
  • Muscle Stretching Exercises*
  • Myostatin
  • Physical Conditioning, Animal / physiology*
  • RNA / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Transforming Growth Factor beta / metabolism


  • Collagen Type III
  • Mstn protein, rat
  • Muscle Proteins
  • Myostatin
  • Transforming Growth Factor beta
  • RNA
  • Insulin-Like Growth Factor I
  • DNA