By Elvis Goren, KOMODO

There is a lot of misconception about heart rate variability (HRV) online and in prominent medical papers. If you search “ What is HRV “ you will see two things. First you’ll see some vague articles from Harvard health, WebMD and Johns Hopkins. However, it is not in the interest of big pharma and big medicine to promote HRV because heart rate variability gives individuals true health independence.

The second thing you will see is articles and product placement from some of the top HRV device companies. Here you will see the fireworks, trying to lead you to purchase their products. But there must be an in between; The Truth.


In technical terms, heart rate variability is the time difference, in milliseconds, between each successive heart beats. Our heart beats aren’t static. Think of the Queen song “We Will Rock You” which is the same beat on and on. Our heart rates are more like “Flight of the Bumblebee.” So from beat to beat to beat, HRV is measuring the change between 2 heart beats as compared to the prior two (see chart below)

What Is HRV heart rate variability
What is HRV (Heart Rate Variability)


So what does this all mean? Essentially, a high heart rate variability is a good thing. It means your overall health, heart, stress level is optimal. A low HRV means the opposite. 

HRV is like your body’s check engine light, an MRI into your internal health, a measure of your stress level, the overall health and wellbeing of your body. It’s truly an incredible tool if you know how it works, and have knowledge of the technology behind it.


Here’s something you won’t read everywhere. Not all HRV is built the same. There are different ways to acquire HRV and one is more accurate than the rest


There are two types of algorithms devices use to display the end result, your HRV score. SDNN simply records your heart rate (BPM), takes an average throughout the day (usually a 24-hour period) and displays your HRV result in the form of milliseconds. This is done by Apple and Fitbit because it’s easy, but not as accurate as the next method. More on that here.

RMSSD actually records the time difference between beats in real time. A more complex (and accurate formula) that is used by companies like Whoop and Komodo’s AIO Smart Sleeve. More  on that here.


No that we’ve talked about the algorithm, let’s talk about the input method. Where is the device acquiring the heart signal from. Almost all companies use the optical sensor because of its versatility and ability to show other information. However, it is much less accurate that an electrocardiogram.

The AIO Sleeve is the only company that extracts HRV value from an ECG / EKG. To get an idea of the difference: a standard optical sensor uses 50 samples per second, whereas ECG uses a minimum of 300 samples per second. This is how often the sensor feeds data to your smartphone. This is quite significant, and is the reason all professionals prefer to work with ECG.


The only person who knows the answer to this question is you. An 80-year-old with a heart condition and a 28-year-old athlete will have different ideas of what is a good heart rate variability. You will first need to establish your average heart rate variability, or baseline and go from there. Spending a few weeks monitoring your HRV throughout the day will give you a sense of where you’re at. Only then can you break down your daily routine and begin optimizing and increasing your HRV.


Many factors will affect your HRV. It takes time to establish what your baseline is, understand your body and begin making the necessary changes. Here are the areas you will want to consider as they all have an affect on your health.

1. Heart Rate Variability and your diet

food sensitivity and heart rate variability - HRV

As mentioned before in the example with the burger, every individual has a unique reaction to different foods even though they aren’t consciously aware. You should check you HRV before and after meals to see how that food affects your body. And it could be different day-to-day depending on how much stress you’ve put your body through that day. So if you eat the same foods every day, and you notice that on Wednesday your HRV dipped significantly after a meal, you should analyze what you did that day and why your body reacted differently. Perhaps you had a fight with a friend, got called in to HR at work or broke up with a significant other. Yes, these things can all contribute to high stress that will inevitably affect everything else you do that day

2. Heart Rate Variability and exercise 

Lots of professional sports teams use HRV as a tool to optimize player performance and recovery. But you don’t need to be a pro to use it. You can use it if you’re doing cross fit, yoga, cycling, even walking your dog and doing lawn work. It’s truly a universal tool. When you exercise, your HRV will automatically decrease. This is because working puts your body under a great amount of stress. But that’s ok. This is good stress. However, if that stress from the workout follows you all day long, that’s not good.

HRV is used to gauge how well one recovers from stress, in this case, it’s exercise. If you are fully recovered and your HRV is back to it’s baseline within 1-2 hours, that’s good! It’s a sign of a healthy functioning body that recovers quickly from training. If your HRV stays the same and doesn’t change for hours upon hours, that’s not a good sign. Maybe you went to hard at the gym or on your bike ride. But with HRV, this could have easily been avoided.

Are You Ready?

Another way we use heart rate variability with activity is readiness. If you know you HRV baseline, or your average, and you notice it’s much lower before heading out on your run, you might want to think twice. Exercising and straining your body when HRV is below it’s average definitely does more harm than good. Could be a sign to take the day off or just do light activates. If HRV is well above your average, you’re good to go! But remember, constantly straining your body when you see a low HRV will not only negatively affect a single day, but could ruin an entire week if it becomes a pattern. Again, HRV gives you control over your own body, and destiny. Cool, right?

3. Heart Rate Variability and Sleep? 

Ok, so yes, many fitness trackers already come with sleep monitoring that you can view on an app. But it’s only tracking how you move at night to determine whether you are in deep sleep or not. While this is good, it doesn’t give us a complete picture. I mean what good is the Mona Lisa without her head, right? 

Measuring HRV before bed and when you wake up gives us true indication of sleep quality and whether one is fully recovered from the day before. If some days are better than others, pay attention to what it is your doing on good sleep days vs. bad ones. Notice your nighttime routine. Are you on your phone a lot? Did you eat before bed? Did you consume alcohol? See what happens to HRV in the morning if you don’t do these things and optimize your sleep.

4. HRV and Stress

Perhaps the most researched topic with respect to heart rate variability is stress and anxiety. Over and over again, clinical research shows a direct correlation between HRV and mental stress. Of course you can’t prevent stress completely, but having visual representation of your stress level is huge. You can identify exactly what things in your life are causing stress and you can look to improve in those moments. Surely you’ve heard people say, “just take a deep breath” when in a tense situation to urge one to calm down. Well, there’s real science behind it. 

Deep breathing exercises have been shown to greatly increase heart rate variability, and thus reducing stress. In a case study conducted using the AIO Smart Sleeve, 50 users measured their HRV before a stressful situation and after, while doing deep breathing. There was an average of 2.2 rise in HRV (out of 5 stars), which is quite significant. 

Warning: do not attempt breathing under water

The Ice Man

Maybe some of you are familiar with Wim Hof, creator of the Wim Hof breathing method. He is well known for immersing himself into ice baths for a record amount of time, and swimming under a sheet of ice in the arctic while only wearing goggles and a pair of trunksHow can he do that? When your body is exposed to that level of cold, your autonomic nervous system (ANS) is fighting like crazy to stay in balance. Deep breathing counteracts the negative affects on your ANS. Now not everyone can do this. But Hof has such exceptional control of his breathing that it almost completely wipes out the stressors that occur from being under such cold temperatures.


Although it’s not a widely used biomarker at this point in time, one thing is for certain; many researchers and clinical studies validate the use of HRV for every day living. According to World Health Organization (WHO)stress if the health epidemic of the 21st century, and heart rate variability might be the only tool that give us insight into the stress and mental health of an individual. While it’s maybe a couple years away from becoming the gold standard for health assessment, there’s still ways to use it now to improve your life. 

In our next blogs we will bring up all the amazing research and show you how you can use it to improve your health.


  1. Excellent read, I just passed this onto a colleague who was doing
    some research on that. And he actually bought me lunch since I
    found it for him smile Thus let me rephrase that: Thank
    you for lunch!

  2. I read this paragraph completely concerning the resemblance of most
    up-to-date and earlier technologies, it’s remarkable product.

  3. Thats not true about the sample rate on current devices with ppg sensors lie Fitbit and Garmin. Some are 50 samples…some go up to 100 but still not close to the accuracy of ECG/ekg samples rate

  4. We’ve been using HRV with our patients at the Cleveland clinic and its wonderful. The best preventative tool out there, lets you see potential heart complications before they occur. an awesome predictor. We used many in the past, might need to give AIO a try.

  5. Our group at UCF actually works on validating HRV devices for professional use. We work with NASA and their pilots also for training purposes and I know they very adamant about using these devices to measure performance and readiness. I’ve seen them use several products, including the AIO Sleeve among several others. Specifically to test autonomic function and optimize their readiness for “long-distance” travel.

  6. heart rate variability is a game changer. I seen people at the gym using all of these fancy wearables to I decided to buy one. And once you read about it, wow. really neat stuff!

  7. We use HRV technology / wearable devices at a nursing home here in Texas with some 400 patients. It’s a game changer for sure! ECG and BPM is one thing, but with heart rate variability and being able to get warning notifications of low readings is great. Highly recommend this for anyone trying to simply live a healthy lifestyle

  8. I’m glad people are finally starting to realize the importance of heart rate variability. My mother had a stroke about a year ago and the doctors told her she was very susceptible to another one and/or other health scares. the Dr was on the front line of HRV technology and gave her a chest strap to wear daily and if it dropped significantly, we should go to the ER. countless times this technology helped, and potentially saved her life. People who doubt this technology are crazy. eventually it will catch up with society and help more people.

  9. Great articles! Hey I have the version 2 of the AIO Sleeve, how can I extract the ECG data from the app onto my computer and into a file? or is there some other way I can do this?

  10. Started reading up on this stuff a little more and it sounds great. This gave me the final push and I gave in and bought one :)…let’s hope it works!

  11. I know Apple is kind of already working on an HRV feature for their iWatch, I’ve tried the app they have now and it doesn’t make much sense. I can imagine what the market will be like once they figure it out but in meantime, great to see that products like these exist. Really a much better indicator than steps and all that other crap.

  12. I couldn’t refrain from commenting. Well written!
    It is the best time to make some plans for the long run and
    it’s time to be happy. I’ve learn this publish and if I may just I wish
    to suggest you few interesting issues or tips. Perhaps you can write next articles
    regarding this article. I want to read more things about it!
    I have been surfing online more than 3 hours today, yet I never found any interesting
    article like yours. It is pretty worth enough for me.
    Personally, if all website owners and bloggers made good content as you
    did, the net will be much more useful than ever before.

  13. I am sure this article has touched all the fitness viewers, its really really
    nice paragraph on using HRV to build a better day.
    Just purchased one of your Sleeves to try.
    Does your site have a contact page? I’m having a tough time locating it but, I’d like to send you an e-mail.
    Any way, great blog and I look forward to seeing it develop over time.

  14. HRV application is not only for training and exercise. There’s so many more uses and applications to every day life like diet and stress. People really need to know these things

  15. I recently started tracking my heart rate variability and it has helped in my training no end. In the past I would have ‘manned -up’ and just pushed through being tired and then most likely injured myself now using HRV I can back off and know when I’m actually overtraining and get a much better performance over time! Highly recommend fitness enthusiasts follow this approach

  16. Agree this is a great tool. I’ve been using since they were made available on the market, brands like AliveCor and Qardio…. tough to use at first but as you learn and wearables become better, definitely worth it whether your active or not

Leave a Reply

Your email address will not be published. Required fields are marked *

Post comment