Researchers at Sherman College of Straight Chiropractic in Spartanburg, SC, have demonstrated that the autonomic nervous system is affected by chiropractic adjustments, and that the area of the spine adjusted may influence whether the affect involves a parasympathetic or a sympathetic response.The study enrolled 40 patients between the ages of 25-55 years. All participants were asymptomatic and free of hypertension and a history of cardiovascular disease.
“Patients were evaluated pre- and post-chiropractic adjustment for the following autonomic responses: blood pressure and pulse rate. Seven patients were measured for heart rate variability. The subjects received either a diversified cervical segment adjustment or a diversified thoracic segment adjustment.”
Results revealed that “diastolic pressure (indicating a sympathetic response) dropped significantly postadjustment among those receiving cervical adjustments, accompanied by a moderate clinical effect (0.50). Pulse pressure increased significantly among those receiving cervical adjustments, accompanied by a large effect size (0.82). Although the decrease in pulse pressure for those receiving thoracic adjustments was not statistically significant, the decrease was accompanied by a moderate effect size (0.66).”
“It is preliminarily suggested that cervical adjustments may result in parasympathetic responses, whereas thoracic adjustments result in sympathetic responses,” conclude the study’s authors. “Furthermore, it appears that these responses may demonstrate the relationship of autonomic responses in association to the particular segment(s) adjusted.
Journal of Chiropractic Medicine – September 2008;7:86-93.