title: Muscle Activity Adaptations to Spinal Tissue Creep in the Presence of Muscle Fatigue.
abstract: OBJECTIVE
  The aim of this study was to identify adaptations in muscle activity distribution to spinal tissue creep in presence of muscle fatigue.
  
  
  METHODS
  Twenty-three healthy participants performed a fatigue task before and after 30 minutes of passive spinal tissue deformation in flexion. Right and left erector spinae activity was recorded using large-arrays surface electromyography (EMG). To characterize muscle activity distribution, dispersion was used. During the fatigue task, EMG amplitude root mean square (RMS), median frequency and dispersion in x- and y-axis were compared before and after spinal creep.
  
  
  RESULTS
  Important fatigue-related changes in EMG median frequency were observed during muscle fatigue. Median frequency values showed a significant main creep effect, with lower median frequency values on the left side under the creep condition (p≤0.0001). A significant main creep effect on RMS values was also observed as RMS values were higher after creep deformation on the right side (p = 0.014); a similar tendency, although not significant, was observed on the left side (p = 0.06). A significant creep effects for x-axis dispersion values was observed, with higher dispersion values following the deformation protocol on the left side (p≤0.001). Regarding y-axis dispersion values, a significant creep x fatigue interaction effect was observed on the left side (p = 0.016); a similar tendency, although not significant, was observed on the right side (p = 0.08).
  
  
  CONCLUSIONS
  Combined muscle fatigue and creep deformation of spinal tissues led to changes in muscle activity amplitude, frequency domain and distribution.
authors: Département d'Anatomie, Université du Québec à Trois-Rivières, Québec, Canada.
authors: Jacques
authors: J
authors: Abboud
authors: Département de Génie Électrique, Université du Québec à Trois-Rivières, Québec, Canada.
authors: François
authors: F
authors: Nougarou
authors: Département des Sciences de l'Activité Physique, Université du Québec à Trois-Rivières, Québec, Canada.
authors: Martin
authors: M
authors: Descarreaux
mesh_terms: D000328:Adult; D000465:Algorithms; D001415:Back / Q000502:physiology; D004566:Electrodes; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000473:pathology*; D011187:Posture; D016059:Range of Motion, Articular; D013131:Spine / Q000503:physiopathology*; D055815:Young Adult