Chiropractic + Naturopathic Doctor

Research Review Corner:May 2012

Shawn Thistle   

Features Research

Association Between Changes in Abdominal and Lumbar Multifidus Muscle Thickness and Clinical Improvement After Spinal Manipulation

Study Title: Association Between Changes in Abdominal and Lumbar Multifidus Muscle Thickness and Clinical Improvement After Spinal Manipulation
Authors: Koppenhaver SL, Fritz JM, Herbert JJ et al.
Publication Information: Journal of Orthopaedic & Sports Physical Therapy 2011; 41(6): 389-399.

Spinal manipulation (SMT) is one of the most frequently utilized treatments for low back pain (LBP), despite conflicting results from the existing body of clinical research on its efficacy.

To improve clinical outcomes with SMT, chiropractors must grasp important concepts from emerging literature on the underlying mechanisms of action of SMT, as well as ways to target those patients most likely to benefit from this treatment. Both areas of knowledge are expanding, shedding important light on our bread-and-butter intervention.


In recent years, research paradigms have shifted from the traditional bone-out-of-place model to increased investigation of the neurophysiological effects of SMT, including its influence on aberrant function of trunk and abdominal musculature. Many agree that the lumbar multifidus (LM) is of particular importance in LBP. In addition to having a cross-sectional area that is twice that of the longissimus thoracis and iliocostalis lumborum, the LM is also a vital stabilizing muscle of the lumbar spine. Further, atrophy and fatty infiltration of the LM muscle have been demonstrated in a variety of LBP populations.

With this in mind, existing evidence suggests that SMT can affect the musculature of the spine and trunk, but the longevity of these effects and their clinical relevance remain controversial. Despite this growing body of research demonstrating physiologic ef­fects following the application of SMT, very few studies have attempted to correlate these changes with clinically relevant outcomes.Therefore, the goal of this study was to examine the relation between reduced disability scores (as determined by the Oswestry Dis­ability Index – ODI) and changes in the LM and abdominal thickness using ultrasound imaging following two SMT treatments, delivered in one week, in patients with LBP.

The results of this paper suggest that a major benefit of lumbar SMT is improvement in the ability of the LM muscle to contract, and that this improved contractility remains one week later. Further, this sustained recruitment of the LM was significantly associated with reduced disability scores as determined by the ODI at one-week follow-up in this data set – this is promising and requires further investigation. 

These results suggest that the impact of manipulation on the multifidus may be more than a reflex response, which would disappear quickly after delivery of the manipulative thrust. It seems reasonable that SMT may somehow “reset” the multifidus to a more optimal functional level through alpha-motor-neuron modulation.The duration of this, or other responses, is an important research question to be pursued in future trials, and the exact mechanisms involved remain largely speculative at this time. 

Regarding the other muscles imaged in this study: The findings regarding the IO are in agreement with previous studies that downplay the role of this muscle in LBP. The results for the TrA, on the other hand, contradict previous studies, highlighting the need for further investigation.

From a clinical perspective, since manipulation seems to improve the contraction of the multifidus, it is within reason that this benefit may be further enhanced by incorporating exercise training targeting the trunk musculature and LM. The addition of exercise in general remains a responsible, evidence-informed approach to LBP.

Dr. Shawn Thistle is the founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners to integrate current, relevant scientific evidence into their practice. Shawn graduated from CMCC and holds an Honours Degree in Kinesiology from McMaster University. He also holds a certificate in Contemporary Medical Acupuncture from McMaster University, and is a Certified Active Release Techniques (ART®) Provider. For more information about the Research Review Service, visit .

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