title: The working mechanism of manual therapy in participants with chronic tension-type headache.
abstract: METHODS
  Prospective longitudinal study.
  
  
  OBJECTIVE
  To explore the working mechanism of manual therapy, we investigated whether 3 cervical spine variables were mediators of the effect of manual therapy on headache frequency. Background Manual therapy has been shown to reduce headache frequency in participants with chronic tension-type headache (CTTH). To what extent specific elements of treatment contribute to the effectiveness of manual therapy in CTTH is unknown.
  
  
  METHODS
  One hundred eighty-two participants with CTTH participated in a prospective longitudinal study: 142 underwent manual therapy and 40 participants received usual care by their general practitioner. Regression analysis was performed according to the steps described by Baron and Kenny, and the proportion of mediated effect was estimated for 3 potential mediators: (1) cervical range of motion, (2) neck flexor endurance, and (3) forward head posture. Outcome was defined as a 50% or greater reduction in headache days.
  
  
  RESULTS
  Neck flexor endurance mediated 24.5% of the effect of manual therapy. Cervical range of motion and forward head posture showed no mediated effect.
  
  
  CONCLUSIONS
  Increased neck flexor endurance appears to be a working mechanism of manual therapy. This finding supports isometric training of neck flexors in participants with CTTH. Trial registered with Netherlands Trial Register (TR 1074).
authors.affiliation: Department of General Practice and Elderly Care Medicine, EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: René
authors.initials: R
authors.lastname: Castien
authors.forename: Annette
authors.initials: A
authors.lastname: Blankenstein
authors.forename: Daniëlle
authors.initials: D
authors.lastname: van der Windt
authors.forename: Martijn W
authors.initials: MW
authors.lastname: Heymans
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000293:Adolescent; D000328:Adult; D002574:Cervical Vertebrae / Q000503:physiopathology; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D026201:Musculoskeletal Manipulations; D009334:Neck Muscles / Q000503:physiopathology; D011187:Posture; D016059:Range of Motion, Articular; D018781:Tension-Type Headache / Q000503:physiopathology / Q000628:therapy*; D055815:Young Adult