The correlation of HRV with health and disease is not new and was already described in the 1960s. In 1996, the European Society of Cardiology and the North American Society of Pacing and Electrophysiology defined the standards and guidelines to measure and interpret the HRV in the context of Healthcare.
Nowadays, Heart Rate Variability (HRV) is ubiquitously used and is at the core of numerous smartwatches, from sleep to blood pressure, stress, general fitness, and even fertility. Athletes use HRV immediately exercising to assess the quality of their training and general fitness level.
Most of us have heard that having a high HRV is a sign of good health, but what about a low Heart Rate Variability? What are the underlying physiological reasons, and should we be concerned when we experience a low HRV episode?
What is the Heart Rate Variability?
In a nutshell, the HRV corresponds to the interval between two consecutive heartbeats measured in milliseconds. These small differences between consecutive heartbeats are minuscule but meaningful since they represent the balance between the autonomic nervous system’s two components.
To be exhaustive, the autonomic nervous system also includes a third sub-system: the enteric nervous system in charge of controlling digestion and bowel movements.
The autonomic system is just like the body auto-pilot and regulates the breathing and heart rate without conscious control. When running, the body will need more oxygen to feed the muscles. Hence the heart will beat faster to increase the blood flow and oxygen supply.
The autonomic system is divided into two branches: the sympathetic and the parasympathetic. The sympathetic nervous system is responsible for the “Fight or Flight” behavior and will prepare the body for survival. The heart will beat faster, and the HRV will typically decrease. On the other hand, when the autonomous system’s parasympathetic branch is in control, the heart will slow down, and the HRV will also typically increase.
Why is my HRV low?
Firstly, it is essential to know that the average HRV will not stay constant throughout life. It will gradually decrease, which is not pathologic but just a normal part of the aging process. Exercising regularly, sleeping well, and eating healthy will increase the HRV. On the opposite, partying all night long, eating junk food, and training only between the fridge and the sofa will have the opposite effect.
Heart Rate Variability is unique for each individual and should be measured appropriately. Comparing it between individuals is meaningless. What matters is the evolution of your HRV. By analyzing HRV trends, you will understand better the constant fights between the parasympathetic and the sympathetic system.
Always consider the HRV as a trend and not in isolation
In 2008, Lampert et al. showed that Decreased Heart Rate Variability was associated with increased inflammation in middle-aged men. HRV is also a relevant indicator of cardiac health.
Consistently low HRV may be an indicator of chronic stress that can lead to heart diseases. According to a study published more than twenty years ago in Circulation, Low HRV is predictive of an increased incidence of death in patients with heart disease and elderly subjects and a higher risk of coronary heart disease in the general population.
Low Heart Rate Variability is also associated with psychiatric disorders, cardiovascular diseases, and diabetes. A low HRV is not a death sentence, though. It just means that it may be good to consider health and fitness and changing your lifestyle.
How to increase my HRV? Is-it possible?
Just like running like improve cardiac health, Heart Rate Variability can also be improved by changing our behavior.
While sleeping, the Heart Rate Variability will increase. In 2013, Gouin et al. from the University of Concordia showed that HRV could be used as a predictor of sleep quality. Pay attention to your bedtime routine and make sure to sleep enough. Recently snoring was also shown as having an impact on the beat to beat variability. Tracking HRV at night time is a good way to analyze the quality of sleep indirectly and potentially implement the necessary changes to improve it.
Meditating and relaxing is a sure way to turn on the parasympathetic branch of the autonomous system. Tyagi and Cohen reviewed 59 studies involving 2358 participants practicing Yoga. The results were unambiguous and showed that Meditation and Yoga affected cardiac autonomic regulation and increased HRV.
Only five minutes for ten days was enough to improve Heart Rate Variability. Recently, Boris Bornemann et al. published the results of their research on the benefits of mental contemplating training on the up-regulation of HRV in the prestigious journal Nature. The results were clear. After three months of training, voluntary regulation of HF-HRV was significantly increased.
It comes as no surprise that nutrition has an impact on our health. Overweight adults are at higher risk of diabetes, high blood pressure, cancer, and many other lifestyle-related diseases. HRV is not only a biomarker of mental health but also of physical health. Improving your diet is an easy way to feel better and be healthier and also proven to reduce Heart Rate Variability.
Numerous scientific studies found a link between low calories or even a Mediterranean diet and an increase in HRV. Interestingly, eating a lot of fishes or fish oil supplements were also associated with a high HRV.
According to Michael et al., exercise is the main factor for improving HRV. The intensity is the training is critical, though. Up to a certain level of moderate-high intensity, HRV will increase to reach a threshold that will not change dramatically even when increasing the intensity. Regular physical activity is the best way to benefit from an improved cardiovascular function, a slimmer silhouette, a clearer mind, and ultimately a higher HRV.
DISCLAIMER: This article is not intended to be a substitute for professional medical advice. Always seek the guidance of your doctor or other qualified health professional.