The study’s authors explain that “the purpose of this study was to examine heart rate variability (HRV) in the presence or the absence of pain in the lower back, while receiving one chiropractic treatment at L5 from either a manually assisted mechanical force (Activator) or a traditional diversified technique spinal manipulation.”As part of the experiment, 51 participants were randomly assigned to a control group, two treatment groups, or two sham groups.

Results revealed that “all groups decreased in value except the control group that reacted in the opposite direction, when comparing the pretests and posttests for the high-frequency component.”

The investigators conclude that “adjusting the lumbar vertebrae affected the lumbar parasympathetic nervous system output for this group of participants. Adaptation in the parasympathetic output, reflected by changes in high frequency, low frequency, and very low frequency, may be independent of type of adjustment. Therefore, the group differences found in the modulation of the HRV would seem to be related to the presence or absence of pain. The autonomic nervous system response may be specific and sensitive to its effectors organ.”

JMPT – May 2009;32:277-86.

www.jmptonline.org