title: Fiber Typing of the Erector Spinae and Multifidus Muscles in Healthy Controls and Back Pain Patients: A Systematic Literature Review.
abstract: OBJECTIVE
  Understanding the changes in muscle fiber typing is relevant in the context of muscle disorders because it provides information on the metabolic profile and functional capacity. The aim of this study was to systematically review the literature comparing muscle fiber typing in the back muscles of healthy subjects with low back pain (LBP) patients.
  
  
  METHODS
  Predefined keywords regarding muscle fiber typing and back muscles were combined in PubMed and Web of Science electronic search engines from inception to August 2014. Full-text articles were independently screened by 2 independent, blinded researchers. Full texts fulfilling the predefined inclusion criteria were assessed on risk of bias by 2 independent researchers, and relative data were extracted. Data were not pooled because of heterogeneity in biopsy locations and population.
  
  
  RESULTS
  From the 214 articles that were identified, 18 met the inclusion criteria. These articles evaluated the muscle fiber type distribution or proportional fiber type area between muscles, muscle layers, men, and women or healthy subjects and LBP patients. Regarding muscle fiber type distribution, findings in healthy subjects and LBP patients show no or inconclusive evidence for intermuscular and interindividual differentiation. Studies evaluating the proportional fiber type area also suggest little intermuscular differentiation but provide plausible evidence that the proportional area occupied by type I fibers is higher in women compared to men. The evidence for differentiation based on the presence of low back pain is conflicting.
  
  
  CONCLUSIONS
  This study found that the evidence regarding muscle fiber typing in back muscles is either inconclusive or shows little differences. The most plausible evidence exists for differentiation in proportional fiber type area depending on sex.
authors.affiliation: Assistant Professor, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium. Electronic address: Barbara.cagnie@ugent.be.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cagnie
authors.affiliation: Research Fellow, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.
authors.forename: Famke
authors.initials: F
authors.lastname: Dhooge
authors.affiliation: Research Fellow, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.
authors.forename: Charline
authors.initials: C
authors.lastname: Schumacher
authors.affiliation: Research Fellow, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.
authors.forename: Kayleigh
authors.initials: K
authors.lastname: De Meulemeester
authors.affiliation: Full Professor, Ghent University Hospital, Department of Geriatrics, Ghent, Belgium.
authors.forename: Mirko
authors.initials: M
authors.lastname: Petrovic
authors.affiliation: Postdoctoral Research Fellow, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.
authors.forename: Jessica
authors.initials: J
authors.lastname: van Oosterwijck
authors.affiliation: Full Professor, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Danneels
mesh_terms: D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000473:pathology*; D008297:Male; D064170:Paraspinal Muscles / Q000033:anatomy & histology*; D012737:Sex Factors
keywords: Low Back Pain; Muscle Fibers; Paraspinal Muscles; Skeletal