Heart Rate Variability- what is HRV and why does it matter?
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What is Heart Rate Variability?
Heart Rate Variability, also known as HRV, represents the variance in time between every heartbeat. So while your Heart Rate measures how many times your heart beats per minute, HRV is the variance in time between those beats.
Why does my Heart Rate Variability matter?
Your heart rate variability is an important expression of how well you are able to deal with and recover from stress, whether that is a physical stressor (like exercise or illness) or an emotional and mental stressor (like anxiety). Increasing your heart rate variability means sleeping better, reducing pain, and improving your overall health and fitness.
What Does My HRV Score Mean?
Your individual heart rate variability is represented by your HRV Score. HRV is typically measured in milliseconds with a higher HRV score indicating better health (see average HRV score graph below).
To understand why a high HRV score is an indication of good health, you have to know that heart rate variability is controlled by the autonomic nervous system (or ANS). The autonomic nervous system regulates involuntary body functions (like digestion, blood pressure, breathing, and heart rate) and is made up of two branches- the sympathetic nervous system ("fight or flight mode") and parasympathetic nervous system ("rest, digest, and recovery mode").
The sympathetic nervous system, commonly known as the "fight or flight" mode, is activated involuntarily when your body perceives a threat. In order to protect itself, the body utilizes the sympathetic nervous system to accelerate breathing, increase blood pressure, and elevate stress hormones like cortisol to make sure you have all the energy and resources necessary to keep yourself safe in a dangerous situation.
The parasympathetic nervous system, the "rest and digest" mode, is the state of relaxation. It decreases your heart rate, slows breathing, and allows your body to return to homeostasis (a natural balance). When you are in a parasympathetic state, your body feels safe reallocating blood flow and energy to restorative functions such as sleep, digestion, and reproduction.
Therefore, a high variance in time between your heartbeats, aka a high HRV score, means that your autonomic nervous system is able to react efficiently by turning on the sympathetic nervous system to deal with stressful situations and then switching to the relaxed parasympathetic state when the threat has passed.
Notice that in the heart rate graph below, there is an even distribution of time between the high's and low's shown (your heart rate increases when you breathe in, and decreases when you breathe out).
A simple metaphor is that your sympathetic nervous system is your gas pedal and your parasympathetic nervous system is the brake — getting "stuck" in either one for too long, especially in your sympathetic stress response, can lead to chronic health issues. Your HRV score shows if your body is able to switch between your "gas pedal" and "brake" to allow your body to function at an optimal level.
There are many ways to improve your HRV which will help with everything from sleep, to digestion, to better mental health.
How to Improve Your HRV
While there is no "right" HRV score for anyone to achieve, it can be helpful to know what an average HRV score is.
But remember, HRV metrics are relative. Learning what an average HRV score is for you allows you to become your own baseline without trying to match a statistic.
You can increase your HRV in many ways, like incorporating exercise and nourishing foods into your routine, but two strategies stand out for measurable HRV improvement:
Breathwork is the practice of intentional breathing that is both incredibly accessible and powerful for changing the state of your body and mind. While breathing can be an automatic result of your nervous system (accelerated breathing in a fight or flight state, slower breathing in a rest and digest state), breathwork gives you the ability to shift your body into a relaxed parasympathetic state by engaging consciously with your breath. You can find easy to follow breathwork exercises here.
Biofeedback uses sensors attached to the body to measure physiological functions, including heart rate and heart rate variability. While biofeedback is typically found in specialized clinics or hospitals, tools like the Flowly: Relaxation Training app allow you to utilize biofeedback for yourself, wherever you are.
The benefit of using HRV biofeedback is that you are able to see your current heart rate and its variation in real time as you work to regulate it. By closing the loop between your mind and body using sensors, you can learn to control your nervous system faster. By seeing your realtime biodata on the screen while engaging in exercises like breathwork or even games, you can learn how to control your nervous system for pain and anxiety reduction, improved sleep and digestion, and better overall health.
TLDR: Your Heart Rate Variability, or HRV, is variance in time between your heart beats and is an important metric for measuring how well your nervous system is able to switch between "fight or flight" (sympathetic state) and "rest and digest' (parasympathetic state).
By increasing your HRV, it's possible to reduce pain, get better sleep, and support your body to become more resilient to stress. You can measure and improve your HRV score by using biofeedback and breathwork, either in a clinical setting or at home by downloading the Flowly app.