To examine the effect of spinal manipulation  on electromyographic (EMG) activity in areas of localized tight muscle  bundles of the low back.


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.


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.


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.

J Manipulative Physiol Ther. 2005 Sep;28(7):465-71. [PMID:16182019]

Author information: DeVocht JW, Pickar JG, Wilder DG. Palmer Center for Chiropractic Research, Davenport, Iowa 52803, USA.