What is heart rate variability?
Heart rate variability or HRV is simply a measure of the variation in time between each heartbeat in milliseconds. For example, if your heart rate is 60 beats per minute, that does not necessarily mean it is beating once every second. Within those 60 minutes, there may be 0.8 seconds between 2 beats, and 1.35 seconds between two others. Our heart changes its rhythm with each beat, and this variation is controlled by a primary part of the nervous system called the autonomic nervous system (ANS). HRV measures the ANS activity, which is creating a balance between sympathetic and parasympathetic nervous systems. (1)
At rest, a high heart rate variability is considered normal, and a low HRV is unfavorable. Whereas, in an active state, lower relative HRV is considered favorable, while a high HRV can be unfavorable. HRV is usually monitored by ECG, blood pressure, and pulse wave signals derived from photoplethysmography(PPG). Heart rate variability is a very essential marker of the efficiency of the cardiovascular system and your overall health and fitness.
What factors affect heart rate variability?
Generally, a low HRV indicates that the body is under stress or danger that could be from anything, for example, psychological events, exercise, internal or external stressors. Higher HRV indicates that the body has a strong ability to fight against stressful conditions. Numerous lifestyle factors or physical influences have both positive and negative effects on HRV. Some are discussed below.
Physiological factors such as age, gender, circadian rhythm affect variation in heart rate in many ways. With increasing age, HRV normally declines. Usually, HRV increases at night and decreases during the day.
Disruption to ANS
The brain innervates the heart by stimulating the autonomic nervous system which is divided into two parts, parasympathetic and sympathetic nervous system. The sympathetic activity leads to an increase in the heart rate(for example: during exercises, stress sports), whereas parasympathetic activity lowers the Heart rate(for example: during sleep). Several diseases have been linked with changes in the ANS, thus altering the pattern of HRV. Heart rate variability provides an insight into the detection of autonomic nervous system impairment and the prediction of neurological disorders. Time-domain statistical methods and nonlinear analysis are proven to detect a disruption in ANS. (2)
Stress is one of the cosmic problems in today’s society. Stress has a psychological origin, but it can cause many physiological changes in your body, and heart rate variation is one of them. Heart rate variability decreases during stressful conditions. Studies have shown that people with social anxiety disorder, panic disorder, and post-traumatic stress disorder(PTSD) had a lower heart rate variability. (3)
Well trained athletes and people who do regular exercise typically have a higher HRV because their heart is pumping blood more efficiently. Physically fit people can easily combat stress and fast heart rate.
The drugs that have a negative influence on HRV include analgesics, beta-blockers, sedatives, and anesthetics. The negative effect of these drugs is thought to be caused by central nervous system depression.
Other factors that affect heart rate variability include nutrition, hormone cycles, illness, and medication.
How to improve heart rate variability
Heart rate variability is an excellent measure of overall fitness and health. Here are a few ways to improve heart rate variability:
- Quality sleep
- Healthy diet
- Breathing exercises
How breathing and meditation improve your heart rate variability?
Meditation is the most powerful practice for increasing focus and attention towards the betterment of lifestyle and improving heart rate variability. When the mind and body are calm, the heart rate varies accordingly and is ready to respond. Meditation and heart rate variability are connected in many ways. Poor heart rate variability can be caused by many factors such as stress, hormone cycle dysfunction, poor nutrition, and other lifestyle problems. Meditation and breathing exercises manage and alleviate all of these problems by bringing in peace and calmness. Meditation, when practiced daily, can improve the sleep cycle, diet, and acts as a stress buster. It exerts positive effects upon HRV by increasing vagal tone. What is good for the mind also tends to be heart-friendly.
Breathing is one of the finest functions of the body, which is involuntary, but we can also take control of it by doing simple breathing exercises. Pranayama breathing or breathing exercises promote relaxation, concentration, and stress reduction. Breathing exercises following 10 seconds stimulates the parasympathetic nervous system- improving HRV. (4)
Coherent breathing or deep breathing is one way to improve HRV, and it is the simplest technique of taking five breaths per minute. It is one of the easiest ways to activate the vagus nerve, which ultimately balances the sympathetic and parasympathetic nervous system. Here’s how to do it:
- Sit upright or lie down and place your hand on your belly.
- Slowly breath in, to the count of 5.
- Slowly breathe out to the count of 5.
- Follow this exercise for 10 to 20 minutes daily.
Meditation has numerous mental and physical health benefits, and mindful meditation is a cornerstone in achieving an optimal HRV. The mind-calming effect of mediation also plays a key role in reducing the risk of heart diseases. Meditation helps you cope up with stress and lets you focus on the present hence decreasing the factors negatively affecting HRV. The idea of heart coherence meditation is quite simple. (5)
- Find a quiet place and start with a strong sense of gratitude.
- Sit upright, close your eyes, and rest one hand on your chest and other on your belly.
- Breathe slowly and deeply in and out through the nose.
- Bring your attention to your breath.
Heart rate variability works regardless of our desire, but our modern sedentary lifestyle wrecks havoc on heart health. We can only improve it by maintaining a healthy lifestyle and focusing on the positivity of breathing exercises and meditation.
- Acharya UR, Joseph KP, Kannathal N, Lim CM, Suri JS. Heart rate variability: a review. Medical and biological engineering and computing. 2006 Dec 1;44(12):1031-51.
- Thayer JF, Sternberg E. Beyond heart rate variability: vagal regulation of allostatic systems. Annals of the New York Academy of Sciences. 2006 Nov;1088(1):361-72.
- Vrijkotte TG, Van Doornen LJ, De Geus EJ. Effects of work stress on ambulatory blood pressure, heart rate, and heart rate variability. Hypertension. 2000 Apr;35(4):880-6
- Tharion EL, Samuel PR, Rajalakshmi R, Gnanasenthil G, Subramanian RK. Influence of deep breathing exercise on spontaneous respiratory rate and heart rate variability: a randomized controlled trial in healthy subjects. Indian J Physiol Pharmacol. 2012 Jan;56(1):80-7.
- Shearer A, Hunt M, Chowdhury M, Nicol L. Effects of a brief mindfulness meditation intervention on student stress and heart rate variability. International Journal of Stress Management. 2016 May;23(2):232.