The effect of cervical and lumbar spinal adjustments on the EMG activity of the lumbar paraspinal muscles in patients with chronic lower back pain

OBJECTIVE: To determine and compare the electromyographic effect of cervical and lumbar spinal adjustments on the lumbar paraspinal muscles in subjects with chronic lower back pain. STUDY DESIGN: Thirty subjects with chronic lower back pain underwent 5 spinal manipulative treatments on alternative days over a 2 week period (excluding weekends) to test the electromyographic effect on the lumbar spinal muscles. SETTING: Technikon Witwatersrand Chiropractic Clinic, Johannesburg, South Africa SUBJECTS: Thirty subjects with chronic lower back pain participated in this study. Each of the subjects was assigned to one of three groups using age-matched sampling methods. Group 1 consisted of 10 subjects (mean age of 25 years) receiving lumbar spine and pelvis adjustments (L1 - L5, including Sacroiliac joints); Group 2 consisted of 10 subjects (mean age of 26 years) receiving cervical spine adjustments (Occiput - C7); and Group 3 consisted of 10 subjects (mean age of 26 years) receiving adjustments to the cervical spine, lumbar spine and pelvis. METHODS: Lumbar paraspinal muscle electrical activity was tested before and after the treatment one, three and five using surface electromyography (sEMG). One pair of bipolar electrodes was placed bilaterally over the paraspinal muscles at the level of L3. Subjects were asked to lie down in a prone position with their arms next to their sides. They were then instructed to perform a single voluntary lower back extension exercise by lifting their chests and shoulders as high as possible off the plinth. Each contraction lasted five seconds. The baseline and peak values from the surface electromyographic meter were recorded, analyzed and compared for reference. Information regarding the intensity and quality of the pain experienced by the subjects were also collected at the start of treatment one, three and five using approved research measurements, i.e. the Oswestry Questionnaire and the Visual Analogue Pain Scale. iv RESULTS: Comparison of the results indicated no statistically significant difference between the three groups and their responses to the treatments. Subjectively, all three groups showed trends of improvement, with group 2 showing the greatest percentage of improvement in pain. Objectively, group 2 also showed the greatest percentage of improvement in the resting rate of the paraspinal muscles, assuming that ideal sEMG resting rate is the lowest one possible. Comparing the results of the contraction ability of the paraspinal muscles, both prior to and after spinal manipulative treatment (SMT), group 1 demonstrated the greatest percentage in improvement followed by group 3. Group 3 also demonstrated the most balanced paraspinal muscles at the end of the study. CONCLUSION: In light of these findings it can be concluded that the treatment protocol as represented by group 2 showed the most favourable treatment efficacy in terms of subjective results and resting rate of the paraspinal muscles. The trends shown in this study should be used and tested in future similar research studies incorporating larger sample groups.Ms. M. Jansen van Rensburg Dr. M. Buchholt