What is HRV?
Heart rate variability (HRV) is a measure of the interval between each of the beats of your heart. The amount of variation is an indication of your overall ability to adapt to the environment. When your body is under high amounts of stress, the HRV becomes lower, reducing your ability to adapt. When you are in a calm and attentive state, then your HRV becomes higher, increasing your ability to adapt.
So More Variability is Better?
Yes. It is a common assumption that a steady heart rate is a sign of better health. When you think about it, it makes a lot more sense that you have better health when you have more variability in your heart rate, since that means your body is adapting to each situation instantly. You should know that a higher HRV means better health. High heart rate variability is associated with having a lower heart rate, and better overall fitness.
For example, if you are checking your heart rate, you may count the number of pulses over a minute. If your pulse is 60 beats per minute, that is an average of 1 per second. If every heart beat occurred exactly every 1.0 seconds, then you would have a low heart rate variability (HRV). Conversely, if the interval between beats varies from 0.7 seconds to 1.3 seconds, your variability is better and you are adapting more fluidly to your body’s needs. In other words, a higher variability is healthier.
When Was Variability First Noticed?
“The Rev. Stephen Hales (1733) was the first to note that pulse varied with respiration and in 1847 Carl Ludwig was the first to record RSA (respiratory sinus arrhythmia). With the measurement of the ECG (1895) and advent of digital signal processing techniques in the 1960s, investigation of HRV and its relationship to health and disease has exploded.” (1)
Why Measure HRV At Rest?
Your body raises your heart beat during exercise, and lower your heart rate at rest. Those new to HRV are often left wondering why we don’t just make you walk on a treadmill to raise your heart rate. HRV, by definition, is the measurement of variability at rest. It is the ability for your body, via the nervous system, to control your heart rate with precision and detail. High HRV is analogous to having better internet to watch a video. Your heart has a clearer and stronger signal, with less lag, that means you have a higher and better HRV.
Over 50,000 Scientific Articles on HRV
HRV is not exactly a household name with the general public. HRV is used by some leading professionals in the health and wellness field. Heart rate variability provides a look at long-term function and health. People who use HRV most in practice are chiropractors and team trainers and conditioning specialists, since they are typically the people trying to enhance and optimize health in humans.
Most notably, scientists have used HRV extensively in research for over 60 years, and there are over 50,000 articles about HRV published in scientific journals.
An Indicator of Damage from Stress
Medical and surgical practitioners are typically not as interested in HRV since it is not a useful predictor of life-threatening illness in the short term. Stress causes damage over the course of decades, and so wellness practitioners find HRV a useful guide for improving lifestyle and performance.
The Autonomic Nervous System (ANS)
Although it is a heart measurement, clinicians use HRV more specifically to see how the autonomic nervous system is behaving. The autonomic nervous system is the “primitive” system in the body that unconsciously controls the trillions of processes in the body that support the life form called “you.” Not primitive at all, when you think about it! The autonomic nervous system is actually a very complex neurologic array within the brain, and spinal cord. It extends into all the organs and glands in your body.
The Balancing Act
The ANS has two sub-systems. The first is the Sympathetic Nervous System or “flight or fight” system. A sympathetic response happens in fearful situations. This means adrenaline will squirt into your blood stream. Physiologically, this can preserve your life if used in short duration. The parasympathetic nervous system, also known as the “rest and digest” response is the counterpart of the flight or fight response. When you have balance between these two systems, you have better adaptability, and better HRV.
Why Measure HRV?
The purpose and mechanism of the chiropractic adjustment is to improve the function of the nervous system. Specifically, the sympathetic (upper back) and parasympathetic (neck and lower back) ganglia are located at the spinal column. One of the goals of the adjustment is to improve nerve function and create sympathetic-parasympathetic balance.
Measuring HRV At Home
There are a number of apps that monitor HRV using a bluetooth monitor (sorry, apple watch is not a good option for this). Some apps are better than others, and you should experiment with scrutiny. On the plus side, measuring HRV is completely non-invasive, so I would not say there is any physical “risk” to trying different ones.
(1) George E. Billman: Heart Rate Variability – A Historical Perspective