Heart Rate Variability - Why You Should Know Yours

February 8, 2016 | Dr. Linda J. Dobberstein, DC, Board Certified in Clinical Nutrition

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 Heart Rate Variability - Why You Should Know Yours
There has been an explosion of personal gadgets and apps to measure all kinds of bodily functions in the last few years. One area on the market has been measuring heart rate variability (HRV). It is a tool that hospitals have used for decades. Elite athletes have used it since the 1970’s to measure overtraining and recovery ability, but now the popularity and usefulness of HRV monitoring reaches far and wide. Step into any gym or have a talk with your personal trainer and you will find several types of personal monitors for measuring HRV. Heart rate variability is certainly important in the athletic realm and finding out if one is overtraining, but it has far reaching applications for monitoring risk and health in the general population. Numerous health concerns are related to HRV changes. Having that physical measurement of HRV is one thing, but knowing how to manage it is another thing.

What is Heart Rate Variability?

HRV is the measurement of time between each heartbeat; it is the rest period between each heartbeat. It is an indicator of how well the autonomic nervous system is managing day to day output and stress. HRV is specifically related to the function of the parasympathetic nervous system, which is the relaxed part of the autonomic nervous system. It is like the brakes on the car. It helps stop or slow down the car/body when our internal body is ramped up or on high alert.

There is another part to the autonomic nervous system, the sympathetic nervous system. The sympathetic nervous system is responsible for alertness, crisis, and is the gas pedal or accelerator of the body. It allows the heart to beat harder and faster to pump more blood, prepares muscles, and increases blood in response to whatever grizzly bear is knocking on the door. The parasympathetic nervous system promotes relaxation and repair, and supports digestion and other internal organs part of the body. The sympathetic nervous system is fight-flight. Problems arise with stress and health when the body is in chronic fight-flight. It dampens the parasympathetic relaxed-repair function. One of the ways to easily and objectively measure this balance is through heart rate variability.

There is a very large nerve in the body that plays an integral role in the management of HRV and interfaces with the parasympathetic nervous system. This nerve is called the vagus nerve or cranial nerve 10. The vagus nerve is actually a pair of nerves that “wanders” through the trunk of the body, hence the nerve’s nick name “the wanderer”. The vagus nerve starts in the brain stem area and extends down through the neck into the abdominal cavity; one branch is on the left and one branch on the right. It innervates or supplies nerve communication to the heart, lungs, stomach, small intestine, gallbladder, liver, spleen, one kidney, and some of the colon. It is also involved with speech, swallowing, some taste perception, and some tissues in the throat, neck and even part of the ear. It is the nerve that talks to our brain telling us what our “gut sense” is. It regulates heart rate and the process of digestion with enzymes, stomach acid, and other gastric juices along with the movement of the food thru the digestive tract. Even the gut bacteria talk to the brain via the vagus thus playing a role in neurotransmitter production and activity.

Do You Have a Healthy HRV?

A healthy HRV will produce a larger gap in time between beats and a higher HRV number. An individual who is over-training in athletics or not recovering well will have low HRV and consequently decreased or plateaued performance. The low HRV reflects higher levels of oxidative stress and insufficient recovery from the activity or previous day. Non-athletes who face illness or injuries have also been shown have low or diminished HRV. The diminished HRV may be an internal sense that the heart rate is elevated, feeling stressed, disturbed sleep, unable to wind-down, moody, digestive upset, short shallow breathing, fatigued, and possibly feeling a “kink in the neck or upper mid-back”.

A more severe example of extreme stress to the vagus nerve and how it affects HRV is fainting, known medically as vasovagal syncope. The person feels hot, nauseated, and lightheaded before losing consciousness. The symptoms reflect changes in blood flow and nervous system function that changed the heart rate with vagus nerve stress. The optimal goal with HRV monitoring is to identify the stress response to the vagus nerve, the brain, and internal organs well before it manifests into bigger problem, like an illness.

Why Heart Rate Variability Matters to You

The disorders associated with poor HRV are numerous. Young and old alike are affected by this variable. Knowing if your HRV is struggling helps provide information about more than just observation. There are several tools that affect HRV that help you put you back in the driver’s seat of your body.

Some of the disorders identified with poor HRV include Alzheimer’s disease, anxiety, atrial fibrillation, autonomic nervous system disorders, blood pressure, cancer, cardiovascular risk, central sensitization and chronic pain, chronic fatigue syndrome/myalgic encephalomyelitis, concussion, COPD, mild cognitive impairment, depression, diabetes (type I and II), eating disorders (anorexia and bulimia), fibromyalgia, headache disorders, heart failure, inflammation, insomnia, irritable bowel syndrome, migraines headaches, obesity, Parkinson’s disease, postural orthostatic tachycardia syndrome, restless legs syndrome, schizophrenia, stomach ulcers, stroke, sepsis, and stress.

What decades of measuring heart rate variability in the hospital has provided is a method of measurement that helps predict and identify the presence of nervous system stress even before the disease is full blown. We can now use personal health tools to measure how much a stressor is wearing the body down. It allows us to measure daily life activities and evaluate if we are “over-training” with our daily wear and tear.

Things that Interfere with HRV

Besides chronic stress and overtraining, there are a few things that may affect HRV and vagus nerve activity from an environmental or external source. Whiplash disorders or hyperextension/hyperflexion neck injuries from a motor vehicle accident can affect HRV. Concussions, EMF exposures in a handful of studies report subtle influences on the autonomic nervous system influencing the HRV. Internal stressors and imbalances with how the immune system, imbalanced gut bacteria, and brain talk to each is now known to cause changes in HRV. At least in the case of multiple sclerosis and perhaps other autoimmune disorders, the change in HRV is related with infections, inflammation, genetics, and environmental factors.

Cardiac health indeed is affected by changes in HRV. One recent animal study described just how diverse stimuli can be and affect the heart and HRV. The study found that high fat diets, obesity, and insulin resistance caused a change in the function of the heart which leads to worsening of HRV. Stimulating the vagus nerve helped improve heart function and HRV. In this study, it showed that supporting healthy vagus nerve activity in these obese-insulin resistant animals protected the heart mitochondria from damage, reduced inflammation, decreased blood pressure, improved adiponectin levels, decreased insulin levels, total cholesterol, triglycerides, LDL cholesterol, and visceral fat. This type of information gives us another tool for measuring heart stress.

Supporting HRV and Vagus Nerve Activity

There are several ways to support healthier HRV and vagus nerve activity. In extreme cases, where severe pathology like intractable epilepsy exists, the medical treatment is to surgically implant a vagus nerve simulator. For the average individual trying to make some positive improvements, thankfully there are much less extreme ways to provide support. Because ongoing stress and the fight-flight stress hormones and chemicals perpetuate lowered HRV and vagus nerve activity, stress reduction is a must.

Taking a break, rest, sleep, stress management skills, being in nature, stretching, yoga, Qi-gong like activities with laughter, walking, acupuncture, chiropractic, and massage, support this healthy neurological response from simple to very complex healing measures of support. In addition, biofeedback and personal portable vagus nerve stimulators may be recommended. There are several immediate ways to stimulate the vagus nerve in mere seconds. This is by humming, singing, or gargling and deep belly breathing. 

It is evident that HRV and vagus nerve activity require sufficient nutrients to maintain function and integrity as this is a neurological function. No matter what your disorder is from heart disease, blood pressure, obesity, migraines, concussion, CFS/ME or fibromyalgia, or any of the disorders linked with poor HRV and vagus nerve dysfunction, there are tools at hand. Simple nutritional deficiencies are common in the general population. Check your HRV with an app, your personal trainer, or at your next medical appointment. Your body may be giving you a significant warning light trying to get your attention before it further toll takes place.

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