The heart, the brain, and the autonomic nervous system.
Heart rate variability (HRV) is an exciting technology for evaluating autonomic nervous system balance and activity. HRV enables doctors of chiropractic to objectively evaluate how effectively the nervous system is regulating the activity of a vital organ.
There is a two way communication system between the brain and the heart. Analysis of the beat to beat patterns of the heart may be used to evaluate balance between the sympathetic and parasympathetic divisions of the autonomic nervous system. When the two branches of the autonomic system are working together at maximum efficiency, you feel "in sync." This is because the sympathetic and parasympathetic divisions are not fighting one another. This state of being is called "entrainment."1
Variability in heart rate reflects the vagal and sympathetic function of the autonomic nervous system, and has been used as a monitoring tool in clinical conditions, characterized by altered autonomic nervous system function.2 Spectral analysis of beat to beat variability is a simple, non invasive technique to evaluate autonomic dysfunction.3
Normative data on heart rate variability have been collected.4,5,6 This technology appears to hold promise for assessing overall fitness. Gallagher et al.7 compared age matched groups with different lifestyles. These were smokers, sedentary persons, and aerobically fit individuals. They found that smoking and a sedentary lifestyle reduces vagal tone, whereas enhanced fitness increases vagal tone. Dixon et al.8 reported that endurance training modifies heart rate control through neurocardiac mechanisms. In occupational health, the effects of various stresses of the work environment of heart patients and asymptomatic workers may be evaluated using heart rate variability analysis.9 Low heart rate variability is predictive of mortality from all causes.10
Zhang et al. reported the results of an exciting study involving 520 subjects in a single visit group, and 111 subjects in a four week group. The purpose of the study was to investigate the effect of chiropractic care in a multi-clinic setting on the balance of the sympathetic and parasympathetic nervous system using HRV (heart rate variability) analysis. The study demonstrated consistent changes in HRV. The authors reported, "The decreased heart rate and increased total power from the HRV analysis indicated a healthy autonomic nervous system balance after correction of vertebral subluxation."11,12
Autonomic dystonia, or acquired dysautonomia, is one of the three elements in the three dimensional model of vertebral subluxation.12 Skin temperature changes, reflecting alterations in vasomotor tone, are used clinically to assess autonomic changes associated with vertebral subluxations, as well as nutritional, exercise, and lifestyle interventions.
Heart rate variability represents an exciting, non-invasive technology to assess subluxation related autonomic function. HRV technology will empower the practicing chiropractor to assess and communicate the far reaching impact of subluxation correction and a healthy lifestyle.
Christopher Kent, D.C.
Christopher Kent is co-founder of the Chiropractic Leadership Alliance. Dr. Kent is a chiropractor and an attorney. He was honored as Chiropractor of the Year by the International Chiropractors Association, and received Life University’s first Lifetime Achievement Award. He may be contacted at
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11. Zhang J, Dean D: "Effect of short term chiropractic care on pain and heart rate variability in a multisite clinical Study." International Research and Philosophy Symposium: Abstracts. Sherman College of Straight Chiropractic, Spartanburg, SC. October 9 10, 2004.
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