The purpose of this study was to determine the neuromuscular  reflex responses of the erector spinae musculature to spinal  manipulative thrusts (SMTs) in patients with LBP. 20 (10 male/10 female,  mean age = 43 yrs.) consecutive LBP patients received MFMA SMTs  delivered to the transverse and spinous processes of T8, T12, L2, L4,  L5, and the sacral base and PSIS by means of an Activator Adjusting  Instrument (AAI) equipped with an impedance head. Surface, linear  enveloped, electromyographic (sEMG) recordings were obtained from  electrodes located bilaterally over the L5 and L3 erector spinae muscles  during each of the thrusts. Repeated pre. post isometric extension  strength tests were performed to normalize reflex data. 1600 sEMG  recordings were analyzed from 20 SMT treatments and comparisons were  made between segmental level, segmental contact point (spinous vs.  tranverse processes), and magnitude of the sEMG reflex response. SEMG  threshold was further assessed for correlation of patient self. reported  pain and disability, Consistent, but relatively localized sEMG reflex  responses occurred in response to the MFMA SMTs. 95 % of patients showed  a positive sEMG response to MFMA SMT, Patients with frequent to  constant LBP symptoms tended to have a more marked sEMG response in  comparison to patients with occasional to intermittent LBP. This is the  first study demonstrating neuromuscular reflex responses associated with  MFMA SMT in patients with LBP.

Reference: Christopher J. Colloca, D.C.1, Tony S. Keller, Ph.D. 2, Daryn E. Seltzer, D.C.3, Arlan W. Fuhr, D.C.1;  Lumbar Erector Spinae Reflex Responses to Mechanical Force, Manually-  Assisted Thoracolumbar and Sacroiliac Joint Manipulation in Patients  with Low Back Pain; Proceedings of the 2000 International Conference on Spinal  Manipulation, Bloomington, MN September 21-23,2000.

1 Postdoctoral & Related Professional Education  Department Faculty, Logan College of Chiropractic, St, Louis, MO, USA;  National Institute of Chiropractic Research, Phoenix, AZ, USA; Private  Practice of Chiropractic, Phoenix, AZ, USA. 2 Professor, Department of Mechanical Engineering  & Department of Orthopedics and Rehabilitation, The University of  Vermont, Burlington, VT, USA. 3 National Institute of Chiropractic Research, Phoenix, AZ, USA; Private Practice of Chiropractic, Phoenix, AZ, USA.