Published Clinical Trials Using the Activator Adjusting Instrument (AAI)

The Activator Method is one of the most widely researched chiropractic techniques and the only instrument adjusting technique with clinical trials to support its efficacy. The following list of clinical trials demonstrate that there is sufficient published evidence that use of the Activator adjusting instrument results in therapeutic benefits equivalent to manual-thrust and/or diversified chiropractic manipulation.


  1. Effects of chiropractic treatment on blood pressure and anxiety: a randomized, controlled trial. Yates RG, Lamping DL, Abram NL, Wright C. J Manipulative Physiol Ther. 1988 Dec;11(6):484-8.

Main Results/Conclusions: Systolic and diastolic blood pressure decreased significantly in the active treatment condition. No significant changes occurred in the placebo and control conditions. Anxiety significantly decreased in the active and control conditions.

  1. Treatment and biomechanical assessment of patients with chronic sacroiliac joint syndrome. Osterbauer PJ, De Boer KF, Widmaier R, Petermann E, Fuhr AW. J Manipulative Physiol Ther. 1993 Feb;16(2):82-90.

Main Results/Conclusions: Activator proved beneficial in treatment of chronic Sacro-Iliac Joint Syndrome (SIJS); average Oswestry Disability Index (ODI) scores diminished from 28 to 13%.

  1. The immediate effect of activator vs. meric adjustment on acute low back pain: a randomized controlled trial. Gemmell HA, Jacobson BH. J Manipulative Physiol Ther. 1995 Sep;18(7):453-6.

Main Results/Conclusions: Both interventions showed improvement in all outcome measures, but no statistical significance between groups.

  1. Comparison of two chiropractic techniques on pain and lateral flexion in neck pain patients: a pilot study. Yurkiw D, Mior S. Chiropractic Technique. 1996 Nov;8(4):155-162.

Main Results/Conclusions: No statistical significance between interventions. Both interventions showed immediate improvement in all outcome measures.

  1. The effects of spinal manipulation on the intensity of emotional arousal in phobic subjects exposed to a threat stimulus: a randomized, controlled, double-blind clinical trial. Peterson KB. J Manipulative Physiol Ther. 1997 Nov-Dec;20(9):602-6.

Main Results/Conclusions: Activator-assisted spinal manipulation significantly decreased the intensity of emotional arousal reported by phobic subjects.

  1. A pilot randomized clinical trial on the relative effect of instrumental (MFMA) versus manual (HVLA) manipulation in the treatment of cervical spine dysfunction. Wood TG, Colloca CJ, Matthews R. J Manipulative Physiol Ther. 2001 May;24(4):260-71.

Main Results/Conclusions: No statistical significance between interventions. Both Activator and manual manipulation showed beneficial effects in reducing pain and disability while increasing range of motion.

  1. Chiropractic treatment of temporomandibular disorders using the activator adjusting instrument: a prospective case series. DeVocht JW, Long CR, Zeitler DL, Schaeffer W. J Manipulative Physiol Ther. 2003 Sep;26(7):421-5.

Main Results/Conclusions: Signs and symptoms of temporomandibular disorders improved with the course of Activator Methods treatment.

  1. A randomized clinical trial of manual versus mechanical force manipulation in the treatment of sacroiliac joint syndrome. Shearar KA, Colloca CJ, White HL. J Manipulative Physiol Ther. 2005 Sep;28(7):493-501.

Main Results/Conclusions: No statistical significance between interventions. Both interventions showed immediate improvement in all outcome measures.

  1. Immediate effect of activator trigger point therapy and myofascial band therapy on non-specific neck pain in patients with upper trapezius trigger points compared to sham ultrasound: A randomised controlled trial. Blikstad A, Gemmell H. Clinical Chiropractic (2008) 11, 23—29.

Main Results/Conclusions: Activator trigger point therapy appeared to be more effective than myofascial band therapy or sham ultrasound in treating patients with non-specific neck pain and upper trapezius trigger points.

  1. Relative immediate effect of ischaemic compression and activator trigger point therapy on active upper trapezius trigger points: A randomised trial. Gemmell H, Allen A. Clinical Chiropractic (2008) 11,175—181.

Main Results/Conclusions: Both interventions showed improvement in all outcome measures, but no statistical significance between groups

  1. Effects of a manually assisted mechanical force on cutaneous temperature. Roy RA, Boucher JP, Comtois AS. J Manipulative Physiol Ther. 2008 Mar;31(3):230-6.

Main Results/Conclusions: Before treatment, the cutaneous temperature (CT) was significantly different between the ipsilateral and the contralateral sides for all subgroups consistent with a positive L4/L5 isolation test. At 10 minutes after intervention, CT increased significantly for the treatment group but not for the sham and control groups. Furthermore, after manipulation using the Activator with a thrust respecting the standard loading principle of the instrument, it produced a secondary cooling at 5 minutes followed by a rewarming at 10 minutes consistent with a neurophysiological response.

  1. Heart rate variability modulation after manipulation in pain-free patients vs patients in pain. Roy RA, Boucher JP, Comtois AS. J Manipulative Physiol Ther. 2009 May;32(4):277-86.

Main Results/Conclusions: No statistical significance between interventions except for control group. Both interventions showed similar modulation of the HRV.

  1. Relative effectiveness and adverse effects of cervical manipulation, mobilisation and the activator instrument in patients with sub-acute non-specific neck pain: results from a stopped randomised trial. Gemmell H, Miller P. Chiropr Osteopat. 2010 Jul 9;18:20.

Main Results/Conclusions: There were no significant differences between the groups at any of the follow up points. All groups exhibited long-term improvement without one being superior to the other.

  1. Mechanical vs manual manipulation for low back pain: an observational cohort study. Schneider MJ, Brach J, Irrgang JJ, Abbott KV, Wisniewski SR, Delitto A. J Manipulative Physiol Ther. 2010 Mar-Apr;33(3):193-200.

Main Results/Conclusions: This study found neither intervention superior to the other, while providing the chiropractic profession with valuable information on the influence of treatment expectation.

  1. Inflammatory response following a short-term course of chiropractic treatment in subjects with and without chronic low back pain. Roy RA, Boucher JP, Comtois AS. J Chiropr Med. 2010 Sep;9(3):107-14.

Main Results/Conclusions: A total of 9 chiropractic lower back manipulations with the Activator caused the mediators of inflammation to present a normalization response in individuals suffering from chronic low back pain.

  1. Changes in Pressure Pain Thresholds and Basal Electromyographic Activity After Instrument-Assisted Spinal Manipulative Therapy in Asymptomatic Participants: A Randomized, Controlled Trial. Yu X, Wang X, Zhang J, Wang Y. J Manipulative Physiol Ther. 2012 Jul;35(6):437-45.

Main Results/Conclusions: The application of Activator instrument resulted in an immediate and widespread hypoalgesic effect with local muscle relaxation in asymptomatic participants.

  1. Comparison of paraspinal cutaneous temperature measurements between subjects with and without chronic low back pain. Roy RA, Boucher JP, Comtois AS. J Manipulative Physiol Ther. 2013 Jan;36(1):44-50.

Main Results/Conclusions: The Paraspinal Cutaneous Temperature (PCT) readings for subjects with chronic low back pain were lower than the asymptomatic, nontreatment group. The PCT temperature of the treatment group normalized after nine (9) treatments.

  1. A pilot study of a chiropractic intervention for management of chronic myofacial TMD. DeVocht JW, Goertz CM, Hondras MA, Long CR, Schaeffer W, Thomann L, Spector M, Stanford CM. J Am Dent Assoc. 2013 Oct;144(10).

Main Results/Conclusions: 721 potential participants were screened, 80 enrolled, and 53 completed the 6 month assessment. In the end, the logistics were found to be manageable. NOTE: This pilot study was funded by a NCCAM TMD study grant (2008) and was a necessary step in preparation for a larger Randomized Control Trial that will provide clinicians with information helpful when discussing treatment options for those who suffer with TMD.

  1. Comparison of Spinal Manipulation Methods and Usual Medical Care for Acute and Subacute Low Back Pain: A Randomized Clinical Trial. Schneider M, Haas M, Glick R, Stevans J, Landsittel D. Spine 2015;40:209-217.

Main Results/Conclusions: This study found that manual-thrust manipulation (MTM) provided slightly greater short-term (at 4 weeks) reductions in self-reported disability and pain scores compared with mechanical-assisted manipulation (Activator) or usual medical care (UMC); Activator was more effective for pain reduction than usual medical care in the first two-weeks. In addition, the benefit of MTM seen at end-of-intervention was no longer statistically significant at 3 or 6 months. All interventions seem similar in effect; they lead to decreased pain and disability.

  1. A Randomized Controlled Trial to Measure the Effects of Specific Thoracic Chiropractic Adjustments on Blood Pressure and Pulse Rate. Roffers SD, Menke JM, Morris DH. Asian Journal of Multidisciplinary Studies, Volume 3, Issue 6, June 2015.

Main Results/Conclusions: Specific thoracic spinal manipulations affected three measures: blood pressure, pulse rate, and changes in hypertension classification only in the active treatment group. Activator instrument’s utility for sham settings was supported for future efficacy studies.

  1. Comparing Outcome Measures in Lumbar Spine Manipulations: Dynamic X-Rays and Oswestry Index.Roy RA, Bouchera JP, Comtois AS. Spine Research, Spine Research. 2016 Vol. 2 No. 1: 12 (iMedPub Journal)

Main Results/Conclusions: Dynamic radiographs and the Oswestry index appear to be sensitive enough to detect a strong effect size after a 9-treatment course of therapy. In addition, a significant correlation was found between pre- and post-treatment measurements of the Oswestry index and dynamic radiographs which could help validate the necessity of continued care.

  1. Manual and Instrument Applied Cervical Manipulation for Mechanical Neck Pain: A Randomized Controlled Trial. Gorrell LM, Beath K, Engel RM. J Manipulative Physiol Ther. 2016 Jun;39(5):319-29.

Main Results/Conclusions: This study demonstrates that a single cervical manipulation is capable of producing both immediate and short-term benefits for mechanical neck pain. The study also may demonstrate that not all manipulative techniques have the same effect. The results reported in this study are consistent with the hypothesis that the biomechanical characteristics of different spinal manipulation techniques may be responsible for varying clinical effects. However, the results are not definitive, and further research investigating the nature of these changes is warranted.

  1. A Prospective, Randomized, Double Blind, Placebo Controlled Clinical Trial Assessing the Effects of Applying a Force to C5 by a Mechanically Assisted Instrument (MAI) on Referred Pain to the Shoulder.  Hardas GM, Murrell GA. Spine (Phila Pa 1976). 2017 Sep 6.

Main Results/Conclusions: The major effect of applying an MAI to the level of C5 of the spine in referred shoulder pain is improved shoulder strength for internal rotation in this randomized double-blinded clinical trial.


Systematic Review

The following systematic review of the literature demonstrates that there is sufficient published evidence that use of the Activator adjusting instrument results in therapeutic benefits equivalent to manual-thrust and/or diversified chiropractic manipulation.

Clinical effectiveness of the activator adjusting instrument in the management of musculo-skeletal disorders: a systematic review of the literature. Huggins T, Boras AL, Gleberzon BJ, Popescu M, Bahry LA. J Can Chiropr Assoc. 2012 Mar;56(1):49-57.

Main Results/Conclusions: “This systematic review of 8 clinical trials involving the use of the AAI (Activator) found reported benefits to patients with spinal pain and trigger points, although these results were not statistically significantly different when compared to the use of HVLA manual manipulation or trigger point therapy.”

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