Spinal adjustments are frequently used by chiropractors to treat chronic pain conditions. Lumbar spinal manipulations have been shown to be effective in patients with low-back pain. But what underlying mechanisms cause spinal manipulation to produce these positive changes?
By focusing their research on asymptomatic patients, a team of researchers was able to shed light on how spinal manipulation treatments inhibit pain. The study investigated the effects of spinal manipulation therapy on the lower back. Specifically, the researchers measured changes in pressure pain thresholds (PPTs) and basal electromyographic activity (BEA) in participants without pain symptoms. It has been hypothesized that spinal manipulation reduces back pain by reducing pressure pain levels and reducing resting muscle tone (monitored through electromyography).
The study involved 30 participants without a current history of lower back pain. Each patient underwent either spinal manipulation or a sham manipulation procedure. Both before and after the treatment, PPT and BEA levels were measured.
Participants receiving spinal manipulation therapy experienced greater improvement in PPT when compared with the control group, along with an immediate decrease in BEA indicating local muscle relaxation. It is hypothesized that these mechanisms may be involved in the clinical effects experienced following spinal manipulation therapy.
Previous studies on the clinical effects of chiropractic treatments have suggested that chiropractic can reduce blood pressure and enhances the body’s stress response.
Yu X, Wang X, Zhang J, and Wang Y. Changes in Pressure Pain Thresholds and Basal Electromyographic Activity After Instrument-Assisted Spinal Manipulative Therapy in Asymptomatic Participants: A Randomized, Controlled Trial. Journal of Manipulative and Physiological Therapeutics 2012; 35 (6): 437-445.