Spinal Manipulative Therapy

A new study examined the effects of spinal manipulative therapy on the trunk and abdominal muscles.

Spinal manipulation was used medicinally as early as 2700 B.C. in ancient Chinese medicine. There are more than 100 distinct chiropractic and spinal manipulative adjusting techniques, and there is variability between practitioners. Some approaches use highly specialized tables or hand-held equipment.

Spinal manipulation is a primary chiropractic therapeutic application. Spinal manipulation is also used in osteopathic medicine and other disciplines.

A spinal manipulation (adjustment) refers to a directed, high-velocity, short-amplitude thrust applied at the end of the passive range of motion to individual segments of the spine. When the joint is passively mobilized, the range of motion is slightly increased. At the end of this range, a resistance is encountered due to tensing of the joint capsule. If the movement is forced beyond this initial barrier (manipulation), a sudden give is felt, a crack may be heard and a range of motion is increased beyond the usual physiological limit into the so-called para-physiological space. At the end of this space, there is the limit of anatomical integrity for the joint. The force of spinal manipulation must be great enough to separate joint surfaces without disturbing their anatomical integrity.

Researchers from the University of Queensland in Australia explained that spinal manipulative therapy is common in the management of low back pain and has been associated with changes in muscle activity, but evidence is conflicting.

The study investigated the effects of spinal manipulative therapy on trunk muscle activity in postural tasks in people with and without low back pain.

In 20 subjects (10 with lower back pain and 10 controls), EMG (electromyography) recordings were made with fine-wire. Standing subjects rapidly flexed an arm in response to a light, before and after a small amplitude end range rotational lumbar mobilization.

The study found that in the control group, there was no change in trunk muscle EMG during the postural perturbation after spinal manipulative therapy. In low back pain subjects, there was an increase in the postural response of the obliquus internus muscle and an overall increase in abdominis muscle EMG.

The study authors concluded that spinal manipulative therapy changes the functional activity of trunk muscles in people with low back pain, but has no effect on control subjects. Additionally, spinal manipulative therapy increased the activity of the oblique abdominal muscles with no change in the deep trunk muscle, which is often the target of exercise interventions.

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References:

1) Ferreira ML, Ferreira PH, Hodges PW. Changes in postural activity of the trunk muscles following spinal manipulative therapy. Man Ther. 2007 Aug;12(3):240-8. Epub 2007 Apr 23. View Abstract.

2) Natural Standard Research Collaboration: The Authority on Integrative Medicine. www.naturalstandard.com. Copyright © 2007.