title: Trunk motor variability in patients with non-specific chronic low back pain.
abstract: OBJECTIVE
  To identify and characterize trunk neuromuscular adaptations during muscle fatigue in patients with chronic low back pain (LBP) and healthy participants.
  
  
  METHODS
  Forty-six patients with non-specific chronic LBP and 23 healthy controls were asked to perform a trunk muscles fatigue protocol. Surface electromyography was recorded using two adhesive matrix of 64 electrodes applied bilaterally over the erector spinae. Pain score, kinesiophobia and physical disability were analyzed through different questionnaires. To characterize motor variability, dispersion of muscular activity center of gravity was computed. Motor variability between groups was compared using repeated-measures analyses of variance.
  
  
  RESULTS
  Score of disability and kinesiophobia were significantly higher in patients with LBP. Results indicated a significant group effect characterized by an increased motor variability in the healthy group through the entire fatigue task on the left (p = 0.003) and right side (p = 0.048). Interestingly, increasing muscle fatigue led to increased motor variability in both groups (on both sides (p < 0.001) but with a greater increase in the healthy group.
  
  
  CONCLUSIONS
  Muscle recruitment is altered in patients with chronic LBP in the presence of muscle fatigue. Consequently, these patients exhibit changes in muscle recruitment pattern and intensity (lower levels of motor variability) during sustained isometric contraction that may be attributed to variation in the control of motor units within and between muscles. However, patients with LBP are able to increase their motor variability over time but with a lower increase compared to healthy participants.
authors.affiliation: Département d'Anatomie, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada.
authors.forename: Jacques
authors.initials: J
authors.lastname: Abboud
authors.forename: François
authors.initials: F
authors.lastname: Nougarou
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pagé
authors.forename: Vincent
authors.initials: V
authors.lastname: Cantin
authors.forename: Daniel
authors.initials: D
authors.lastname: Massicotte
authors.forename: Martin
authors.initials: M
authors.lastname: Descarreaux
mesh_terms: D000328:Adult; D059350:Chronic Pain / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D060726:Torso / Q000503:physiopathology