For many people who suffer from low back pain, chiropractic treatments ease their symptoms and increase flexibility. But why does it work? And which patients are most likely to benefit? Recently, a team of researchers based in the United States and Australia set out to investigate the effect of one chiropractic technique on spinal stiffness in patients with low back pain. They found that chiropractic manipulation can have an immediate effect on spinal stiffness and muscle growth in certain patients.
Repeated studies have confirmed the effectiveness of high impact, low velocity spinal manipulation (SMT) for reducing low back pain. Yet although it is known that SMT has a direct effect on spinal muscles, and that it stimulates a patient’s nervous system, many questions remain about exactly how SMT works. For this study, the researchers recruited 48 subjects with low back pain from physical therapy clinics and through community advertisements. The subjects were evaluated for several factors that might decrease the likelihood that their treatment would succeed – factors such as longer length of injury and fear avoidance (avoiding activity because of the fear that it may cause pain).
Each participant underwent three SMT sessions, held over a one-week period. Before and after each session, the participants rated their pain levels on a scale of 0-10 and were measured for spinal stiffness. The researchers also took ultrasounds to assess the thickness of the patient’s back muscles.
Their results showed that after patients received SMT, there was an immediate and measurable improvement in stiffness. The patients also reported experiencing less disability from their low back pain after SMT. In their measurements of muscle growth, researchers found that muscle thickness increased more quickly in patients who had been categorized as likely to have a positive outcome. This muscle increase lasted through the one-week follow-up period, which indicates that the benefits of SMT could be prolonged, especially when combined with exercise treatments designed to build muscle in the lower back.
Although the researchers acknowledge that their sample size was small, and their results preliminary, these findings help confirm that chiropractic can have immediate beneficial effects for patients suffering from low back pain. They also show that the human body has a complicated reaction to SMT, with both stiffness and muscle thickness playing a roll in the outcome of treatment.
Fritz JM, Koppenhaver SL, Kawchuk GN, Teyhen DS, Hebert JJ, Childs JD. Preliminary investigation of the mechanisms underlying the effects of manipulation: exploration of a multi-variate model including spinal stiffness, multifidus recruitment, and clinical findings. Spine. 2011 March 15.