title: Spinal manipulation alters electromyographic activity of paraspinal muscles: a descriptive study.
abstract: OBJECTIVE
  To examine the effect of spinal manipulation on electromyographic (EMG) activity in areas of localized tight muscle bundles of the low back.
  
  
  METHODS
  Surface EMG activity was collected from 16 participants in 2 chiropractic offices during the 5 to 10 minutes of the treatment protocol. Electrodes were placed over the 2 sites of greatest paraspinal muscle tension as determined by manual palpation. Spinal manipulation was administered to 8 participants using Activator protocol; the other 8 were treated using Diversified protocol.
  
  
  RESULTS
  Electromyographic activity decreased by at least 25% after treatment in 24 of the 31 sites that were monitored. There was less than 25% change at 3 sites and more than 25% increase at 4 sites. Multiple distinct increases and decreases were observed in many data plots.
  
  
  CONCLUSIONS
  The results of this study indicate that manipulation induces a virtually immediate change, usually a reduction, in resting EMG levels in at least some patients with low back pain and tight paraspinal muscle bundles. In some cases, EMG activity increased during the treatment protocol and then usually, but not always, decreased to a level lower than the pretreatment level.
authors.affiliation: Palmer Center for Chiropractic Research, Davenport, Iowa 52803, USA. devocht_j@palmer.edus
authors.forename: James W
authors.initials: JW
authors.lastname: DeVocht
authors.forename: Joel G
authors.initials: JG
authors.lastname: Pickar
authors.forename: David G
authors.initials: DG
authors.lastname: Wilder
mesh_terms: D001415:Back; D004576:Electromyography; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology* / Q000628:therapy*; D020393:Manipulation, Spinal; D018482:Muscle, Skeletal / Q000503:physiopathology*