title: Establishment of an animal model for delayed-onset muscle soreness after high-intensity eccentric exercise and its application for investigating the efficacy of low-load eccentric training.
abstract: BACKGROUND
  Delayed-onset muscle soreness (DOMS) occurs after unaccustomed exercise and is particularly associated with eccentric exercise. Previous studies have proposed the use of a single bout of eccentric exercise to prevent the muscle damage subsequent to a bout of eccentric exercise. This study aimed to establish a suitable animal model to evaluate the pain in DOMS and to assess whether low-load eccentric training confers a protective effect against a subsequent high-intensity eccentric exercise bout.
  
  
  METHODS
  Thirty-six female Wistar rats were divided into five groups: rats that received muscular compression only (Comp); those that received high-intensity eccentric exercise only (HE); those that received muscular compression at 3, 24, 48, and 96 h after high-intensity eccentric exercise (HE + Comp/3, 24, 48, and 96 h); those that received muscular compression 48 h after a single low-load eccentric exercise (LE); and those that received a week of low-load eccentric training before high-intensity eccentric exercise, which was followed by muscular compression 48 h later (LET). Immunohistochemistry was used to investigate c-fos expression in the dorsal horn of the spinal cord.
  
  
  RESULTS
  For the HE + Comp/48 h rats, the total number of c-fos-positive neurons at the L2-3 segments was significantly greater than that in the Comp and HE rats in the same segments. A week of low-load eccentric training resulted in a decreased number of c-fos-ir neurons relative to that in the HE + Comp/48 h rats.
  
  
  CONCLUSIONS
  Muscle tenderness after high-intensity eccentric exercise was evaluated by c-fos expression in the dorsal horn of the rat spinal cord. Using this rat model, the present study clarified that the muscle tenderness following high-intensity eccentric exercise is inhibited by prior low-load eccentric training.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Science, Kanazawa University, 13-1, Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan. t.munehiro1976@gmail.com
authors.forename: Teppei
authors.initials: T
authors.lastname: Munehiro
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kitaoka
authors.forename: Yoshimichi
authors.initials: Y
authors.lastname: Ueda
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Maruhashi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsuchiya
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D059352:Musculoskeletal Pain / Q000209:etiology*; D010805:Physical Conditioning, Animal / Q000009:adverse effects* / Q000379:methods*; D020671:Posterior Horn Cells / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar
chemical_list: D016760:Proto-Oncogene Proteins c-fos