title: Patients with temporomandibular disorders have increased fatigability of the cervical extensor muscles.
abstract: OBJECTIVE
  To determine whether patients with myogenous and mixed temporomandibular disorders (TMD) have greater fatigability of the cervical extensor muscles while performing a neck extensor muscle endurance test (NEMET) when compared with healthy controls.
  
  
  METHODS
  A total of 151 individuals participated in this study. Of these 47 were healthy controls, 57 patients had myogenous TMD, and 47 patients had mixed TMD. All patients performed the NEMET. The patients were instructed to maintain a prone lying position with the neck unsupported as long as possible, stopping at signs of fatigue or any discomfort. Electromyographic activity of the cervical extensor muscles during the NEMET and the holding time were collected for all patients and were compared across groups. A 1-way analysis of variance was used to evaluate the differences in holding time between patients with TMD and healthy controls. A mixed model analysis was used to evaluate the differences in normalized median frequency at different times (fatigue index) for the cervical extensor muscles while performing the NEMET between patients with TMD and controls.
  
  
  RESULTS
  There were statistically significant differences (P<0.05) in the slopes of the normalized median frequency between patients with TMD and healthy controls at 10, 30, 40, 50, 60, 70, 80, 90, and 100 seconds of the NEMET. Holding time was significantly reduced in both patients with myogenous TMD and mixed TMD when compared with healthy controls (P<0.05).
  
  
  CONCLUSIONS
  These results highlight the fact that alterations of endurance capacity of the extensor cervical muscles could be implicated in the neck-shoulder disturbances presented in patients with TMD.
authors.affiliation: Faculty of Rehabilitation Medicine, University of Alberta, Alberta, Canada. susanarmijo@gmail.com
authors.forename: Susan
authors.initials: S
authors.lastname: Armijo-Olivo
authors.forename: Rony A
authors.initials: RA
authors.lastname: Silvestre
authors.forename: Jorge P
authors.initials: JP
authors.lastname: Fuentes
authors.forename: Bruno R
authors.initials: BR
authors.lastname: da Costa
authors.forename: Paul W
authors.initials: PW
authors.lastname: Major
authors.forename: Sharon
authors.initials: S
authors.lastname: Warren
authors.forename: Norman M R
authors.initials: NM
authors.lastname: Thie
authors.forename: David J
authors.initials: DJ
authors.lastname: Magee
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D009334:Neck Muscles / Q000503:physiopathology*; D019547:Neck Pain / Q000175:diagnosis / Q000209:etiology*; D010147:Pain Measurement; D010807:Physical Endurance / Q000502:physiology*; D010808:Physical Examination; D013705:Temporomandibular Joint Disorders / Q000150:complications* / Q000175:diagnosis; D013997:Time Factors; D055815:Young Adult