The magnitude of muscle strain does not influence serial sarcomere number adaptations following eccentric exercise

Timothy A. Butterfield, Walter Herzog

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


It is generally accepted that eccentric exercise, when performed by a muscle that is unaccustomed to that type of contraction, results in a delayed onset of muscle soreness (DOMS). A prolonged exposure to eccentric exercise leads to the disappearance of the signs and symptoms associated with DOMS, which has been referred to as the repeated bout effect (RBE). Although the mechanisms underlying the RBE remain unclear, several mechanisms have been proposed, including the serial sarcomere number addition following exercise induced muscle damage. In the traditional DOMS and RBE protocols, muscle injury has been treated as a global parameter, with muscle force and strain assumed to be uniform throughout the muscle. To assess the effects of muscle-tendon unit strain, fiber strain, torque and injury on serial sarcomere number adaptations, three groups of New Zealand White (NZW) rabbits were subjected to chronic repetitive eccentric exercise bouts of the ankle dorsiflexors for 6 weeks. These eccentric exercise protocols consisted of identical muscle tendon unit (MTU) strain, but other mechanical factors were systematically altered. Following chronic eccentric exercise, serial sarcomere number adaptations were not identical between the three eccentric exercise protocols, and serial sarcomere number adaptations were not uniform across all regions of the muscle. Peak torque and relaxation fiber strain were the best predictors of serial sarcomere number across all three protocols. Therefore, MTU strain does not appear to be the primary cause for sarcomerogenesis, and differential adaptations within the muscle may be explained by the nonuniform architecture of the muscle, resulting in differential local fiber strains.

Original languageEnglish
Pages (from-to)688-700
Number of pages13
JournalPflugers Archiv European Journal of Physiology
Issue number5
StatePublished - Feb 2006


  • Delayed onset muscle soreness
  • Force-length relationship
  • Muscle injury
  • Repeated bout effect
  • Sarcomerogenesis

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)


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