What Is Heart Rate Variability? - Hanu HRV
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What Is Heart Rate Variability?

What is heart rate variability?

Pretty much everyone knows what their heart rate is. If you don’t, your heart rate is simply the number of times your heart beats per minute. It is a good indicator of your fitness level and your overall health. However, another metric has grown in popularity among medical and health/wellness communities over the last few years.

This metric is your heart rate variability. Your heart rate variability can tell you even more information about your body, how you handle stress, and your overall health. So, what is heart rate variability, otherwise known as HRV?

Your heart rate variability (HRV) is the variation in your heartbeats over time. Even more specifically, HRV is the variation in time between successive heartbeats. Heart rate variability occurs because your heart doesn’t beat like a metronome.

A steady heartbeat, without variability, is a sign of significant problems. Instead, your heart beats in a slightly irregular pattern.

HRV Definition and Image

Heart rate variability is perfectly healthy. It’s your body’s natural response to different environmental and physiological stimuli. HRV is a proxy that measures the human stress response and the autonomic nervous system. It should serve as a guide, not a diagnostic.

Different stimuli constantly bombard you for the 18-ish hours that you’re awake. In each situation, your body reacts slightly differently. Under the surface, without even realizing it, your heart is working to keep your body balanced during these situations. Ideally, an adaptive heart and nervous system regulate blood pressure, stress, and resiliency.

Luckily, your body automatically handles this process, so you don’t need to think about it. Let’s take a closer look at how it works.

What causes heart rate variability?

The Autonomic Nervous System (ANS) is a division of the Peripheral Nervous System (PNS) and consists of three branches: Sympathetic, Parasympathetic, and Enteric Nervous Systems. Although the ENS also plays a role in controlling heart rate variability, for now, we will focus on the sympathetic and parasympathetic branches:

  • The Sympathetic Nervous System (SNS)

    – This system is sometimes known as your body’s Fight or Flight system, which has some truth. Your SNS is activated during moments of extreme stress (ex: a car crash). During events like this, your SNS kicks in to dilate your pupils, increase your heart rate for increased oxygen and nutrient delivery, increase the rate of glucagon to glucose (increased cellular fuel), and more. All of this is a way of getting your body ready for action and sending it into fight or flight mode.
  • The Parasympathetic Nervous System (PNS)

    – This system is sometimes known as your body’s Rest and Digest system. The PNS kicks in when it’s time to relax by enhancing peripheral and gastric blood flow (for digestion), enhancing salivation, constricting the pupils, slowing heart rate, constricting airways, etc. This branch of the nervous system is all about conserving energy. 

The two branches have a fascinating relationship, being both antagonistic and complementary. You can think of the SNS as the gas pedal while the PNS is the brake. Check out the Psychophysiology 101 Pt. 2 article for an in-depth review of these systems.

What is a good heart rate variability?

Heart rate variability is a highly individualized metric. For this reason, there’s no such thing as a “good” heart rate variability. It’s a little bit like how there’s no single “good” weight. A healthy weight for a professional football player would not be considered a healthy weight for a ten-year-old girl.

Essentially, a “good” HRV for you will differ from what’s considered a good HRV for your friends and family. It is important to never compare your HRV to anyone else’s.  

A healthy heart rate variability depends on several factors, including:

  • Genetics
  • Age
  • Fitness level
  • Lifestyle
  • Gender
  • Environment 

Another critical component to understand is that HRV is only “high” or “low” relative to your baseline. Determining your body’s natural HRV is the first step. From there, you can understand how your HRV deviates over time. Once you know your baseline, you can determine if your HRV is low or high (for you).

However, there are generalizations. For example, younger people tend to have a higher HRV than older people. Men tend to have higher HRVs than women. And people who have high cardio-respiratory fitness tend to have the highest HRVs of all. A good example is a professional athlete.

Benefits of a higher HRV

There are plenty of incentives to increase your heart rate variability. Your HRV is associated with both your physical and mental health.

  • Physical benefits – A higher HRV improves your cardiac autonomic nervous system. It reduces all significant cardiovascular risks, such as heart disease, high heart rate blood pressure, and even heart attack or failure.

  • Mental benefits – A higher HRV also drastically increases your mental health and helps your body handle stress better, reducing the risks of anxiety and depression.

With that in mind, let’s look at some factors that impact your HRV.

What affects my heart rate variability?

There are dozens of factors that can impact your heart rate variability. Some factors, like age and gender, are totally out of your control. Other factors, such as hormones, illness, and emotions, can be controlled in some capacity.

Factors you can control

Breathing – Even an act as small as your breathing can significantly impact your heart rate variability. When you take a deep breath in, your heart rate speeds up. When you breathe out, it slows down. This change in your heart rate speed while breathing is called respiratory sinus arrhythmia (RSA).

Health and wellness professionals stress the importance of controlling your breathing. For example, a yoga instructor will instruct you to link your breathing to your stretches to optimize the health impact.   

Sleep – The quality and quantity of your sleep also play a significant role in impacting your HRV. More high-quality sleep tends to lead to a higher HRV. Less sleep, or lower-quality sleep, tends to decrease your HRV.

Stress – Stress is another factor that plays a significant role in your HRV. A lot of this comes down to your daily routine. Do you work in a highly stressful work environment? Or, do you have drama in your life that causes you to stress out? These are both factors that could contribute to changes in HRV.

Fitness – In general, regular exercise can lead to a higher HRV, especially as you increase cardio-respiratory fitness (i.e., VO2 Max). However, it’s possible to overtrain, which can lower your HRV. As with most things, the key is to find a balance that’s right in the middle.

Luckily, all of these factors are under your control. By improving these areas, it’s possible to improve your HRV. But, before you do that, you need to establish your HRV baseline numbers.

How do I measure heart rate variability?

Your heart rate variability is the difference in your heartbeats measured in milliseconds. The best way to determine your HRV is to use a wearable device to track your biometric data.

These types of wearable devices, like Hanu, measure biometric data such as your heart rate and how it fluctuates. The longer you wear your Hanu, the more data points we can collect and the more tailored your score will be. Why is collecting this data so necessary?

  1. It gives you an idea of what causes you to stress during your day-to-day life.
  2. It can reveal long-term trends that may be influencing your HRV. 
  3. You can get real-time feedback that helps you deal with stressful situations at that very moment.

A key point to remember is that your baseline HRV is not as important as how much you can control HRV, primarily through breathing–this is a sign of autonomic control/regulation.

Measuring your HRV is not a fitness competition. You shouldn’t focus on comparing your score against others. Instead, your focus should be on using HRV as a proxy for assessing your stress response so that it can inform training. The end goal is to use HRV as a guide to inform better self-regulation of your stress response. 

An HRV that’s trending upwards can signify that you are improving your overall health (both physically and mentally). It can represent lower blood pressure, less anxiety/depression, and fewer cardiovascular issues. On the other hand, a downward trending HRV can negatively affect your physical and mental health.


A key thing to remember is that baseline HRV (your average number) is not nearly as important as how well you can modulate HRV, at will, when needed. In other words, the more autonomic control that you have, the more resilient you are to stress.

It’ll be easier than you think!

Remember, the entire premise behind measuring your HRV is to improve your stress resiliency. Your HRV is a proxy of efficacy. Monitoring your HRV over time can let you know if you are getting better at handling stress.

It’s worth noting that obtaining data on your heart rate variability has come a long way. Today, the data can be gathered by simply wearing a device that tracks your biometric data. This process can be easily implemented into your daily routine.

At Hanu, we go above and beyond to make the process as simple as possible.

First, we combine dozens of different metrics into a straightforward score. Then we give you real-time feedback on whether your score is increasing or decreasing. If it’s decreasing, then don’t worry. We also provide you with proven exercises that can help you get back on track.

Your heart rate variability plays a crucial role in your mental and physical health. Since it happens automatically, there’s a good chance you don’t even realize the extent to which your heart is working for you–-or giving you warning signs. And while many factors that influence your HRV are out of your control, there are also ways that you can actively improve your HRV.

Make today the day to start improving your HRV, lowering stress, and boosting your overall health.

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