Now let’s return to the variability example used earlier. The research shows that a heart rate that varies from beat to beat, is healthier than someone who has a heart rate that consistently stays at the same interval. This changing heart rate is indicative of a resilience of the heart showing a stronger parasympathetic influence on the nervous system, and a greater ability to rest and digest. Conversely, a consistent heart rate shows less resilience and a stronger sympathetic influence on the nervous system, and a more stressed nervous system. This person may have what I have written about in the past, adrenal stress. There are also measurements made of the High Frequency (HF) waves (associated with parasympathetic tone), the Low Frequency (LF) waves (associated with sympathetic tone), and Very Low Frequency (VLF) waves (associated with neurohormonal tone) of the heart. These wavelengths are analogous to brain waves seen on an EEG, and give a more complex understanding of the autonomic nervous system. There is also a respiratory value that influences the overall score. Therefore, by looking at HRV, we see the balance or imbalance of the autonomic nervous system. Essentially, what is being measured is vagal tone. The vagus nerve is the 10th cranial nerve that controls most of the parasympathetic nervous system and the electrical signals of the heart. The word vagus (Latin) means wandering and it wanders to every part of our body, including all digestive areas, glands and organs.
Research has shown that a strong vagal tone, and a strong heart rate variability can have positive effects on many problems such as depression and anxiety, high blood pressure, resistance and strength of the immune system, predictive risk for heart attacks and strokes along with gauging whether an exercise program is being too stressful for an athlete. Because we are measuring the autonomic nervous system and we know it’s effects branch throughout our body, the algorithm that computes Heart Rate Variability could just as accurately be called Health Resiliency Value.
Historically machines used to measure HRV cost thousands of dollars, but today’s technology uses small devices linked to a phone app that can give you the same information at a fraction of the cost. Measurement should be taken in a seated position after waking.
There are several companies with devices to measure HRV. Some have chest straps with a blue tooth sensor that I avoided because of the inconvenience of application. The ithlete monitor has a finger sensor that plugs into the phone, and gives you an overall HRV score. HeartMath has an ear clip (inner balance) that can plug into an iphone or ipad or an emWave2 for Android users.
The advantage of the HeartMath products is you can use their app as abiofeedback device to train yourself to enter a zone that HeartMath callsCoherence. Coherence is a highly efficient physiological state in which the nervous, cardiovascular, hormonal, and immune systems are working efficiently and harmoniously. The positive effects of meditation have been well documented, but now we have a technology that merges science, with meditation to improve our health!
The ithlete system is best used to determine workout intensity for the day and avoid overtraining on a day you are not up to it.
For those with more challenges in life, such as GERD, IBS, chronic musculoskeletal inflammation, and hypertension, the HeartMath products and their biofeedback capabilities would be best. Chiropractic adjustments to the cervical spine surrounding the vagus nerve can improve HRV. A study of two groups of ten people in the March 2015 Journal of Chiropractic Medicine showed improvements in HRV and blood pressure after adjustments. If you think you would benefit from HRV and would be interested in talking with me further about which monitor might be best for you, please call me at the office. I am also attaching two screen shots from my iphone to show both the ithlete and Heartmath apps. The Heartmath summary shows how much time I spent in the red, blue and green (coherence zone) during my session. It also shows how many points you earn by doing so and that can be a way of setting daily goals for yourself.