title: Human muscle proteome modifications after acute or repeated eccentric exercises.
abstract: BACKGROUND
  Delayed-onset muscle soreness (DOMS), a condition triggered by eccentric exercise, affects muscle cells at a biochemical level in a poorly understood fashion. The objective of the present study was to examine human muscle proteome modifications induced by strenuous eccentric exercises after a specific training aimed to prevent DOMS.
  
  
  METHODS
  Biopsy samples of the rectus femoris were obtained from healthy human volunteers in three successive conditions: 1) at rest, 2) 24 h after an injuring exercise protocol consisting of three series of 30 maximal contractions of the quadriceps on an isokinetic dynamometer, and 3) 24 h after a similar exercise bout preceded either by five eccentric training sessions or by no training.
  
  
  RESULTS
  Muscle damage was assessed before and 1 d after each maximal eccentric test by comparing three indirect markers: plasma activity of creatine kinase, muscle stiffness, and subjective pain intensity. Compared with the first eccentric test, those markers were reduced after the second test and further reduced if this second test followed the eccentric training, thus confirming the protective effect of such training. Muscle protein extracts were subjected to a two-dimensional difference gel electrophoresis proteomic analysis coupled with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry protein identification. Surprisingly, we observed that myosin heavy chains decreased after the first eccentric test and were reduced further with other contractile proteins after the second test. Furthermore, the expression of several glycolytic enzymes decreased only after the second test, which was preceded by a specific training.
  
  
  CONCLUSIONS
  These findings suggest that the eccentric training resulted in a switch to oxidative metabolism, which may be associated with protection from DOMS.
authors: GIGA - Neuroscience, University of Liège, Belgium.
authors: Stéphanie
authors: S
authors: Hody
authors: Pierre
authors: P
authors: Leprince
authors: Kjell
authors: K
authors: Sergeant
authors: Jenny
authors: J
authors: Renaut
authors: Jean-Louis
authors: JL
authors: Croisier
authors: François
authors: F
authors: Wang
authors: Bernard
authors: B
authors: Rogister