News - Chiropractic
chiropractic and the whole body response pt. 2/3
September, 2009
Prepared by: Shane J. Lynch, D.C.
Budgell B, Polus B. The effects of thoracic manipulation on heart rate variability: a controlled crossover trial. J Manipulative Physiol Ther 2006; 29: 603-610.
Heart rate variability (HRV) is an analytical technique that examines the beat-to-beat oscillations /fluctuations in heart rate. In other words, HRV is a representation of the effects that the sympathetic (SNS) and parasympathetic nervous systems (PNS) have on each heart beat, contributing to the overall heart rate. Collectively the SNS and PNS are referred to as the autonomic nervous system and it is this system that controls all of our visceral activities (internal organs, blood vessels, glands). In relation to heart rate, the SNS increases it, while the PNS causes a decrease. Heart rate variability (HRV) can and is used to determine the presence of heart disease, and this calculation alone is considered reliable enough to conclude that a patient is in “good health”. In addition to its use in cardiology, HRV is also used in the fields of neurology, psychology, psychophysiology, obstetrics, anesthesiology and psychiatry.
In regards to the title of this paper, manipulation is another word for chiropractic adjustment, and the thoracic spine is located from the base of your neck to the bottom of your ribs, or the beginning of your low back. With this in mind, the authors of this study investigated the effects that chiropractic adjustments administered to the upper back had on heart rate, or the fluctuations between the SNS and PNS activity. Below are a couple key points.
Key points:
“It has previously been shown that cervical (neck) manipulation results in changes in HR (heart rate) and HRV that are not achieved with a sham adjustment”.
In these studies the participants were randomly assigned to be in either the treatment or control group. Those in the control group did not receive any treatment and had their values measured at the beginning and end of the study. Those in the experiment group were randomly assigned to be in a group that either received a real chiropractic adjustment/manipulation or a sham/fake adjustment. This gives the researchers plenty of data and the ability to determine that the effects were not placebo driven, which is what would presumably occur with a sham adjustment.
“Exit questioners were provide but subjects did not report unpleasant effects from treatment”
This is an important point and means that those receiving the adjustments found them to be comfortable. Discomfort and fear, in general, cause a natural increase in heart rate and blood pressure. These sensations, if experienced by the participants during the adjustment, would have potentially affected the overall results.
“The results indicate that thoracic spinal manipulation was associated with changes in HRV that were not duplicated by a sham procedure in healthy young adults”
“The sham manipulation had no effect on measures of HR, whereas the thoracic manipulation did”
Wrap up:
These data provide evidence that chiropractic adjustments do have an effect on HRV. Although this is only one of a hand full of studies related to chiropractic and cardiovascular health, it is a promising study and supports the chiropractic objective of removing spinal subluxations/misalignments to improve the function of the nervous system. The above findings are another good reason to get your spine checked periodically.
