Heart rate variability: Why we are glad to see it in the new Fitbit

We get to know what HRV brings to the party
Heart rate variability needs more love

It's only recently that I've really started to appreciate the value of having a heart rate sensor on my fitness tracker or running watch while I'm out running or grabbing some time in the gym.

Okay, I know a lot of those optical sensors are not great at the moment, but swapping long runs for shorter bursts of heart rate zone training and understanding my resting heart rate has definitely changed the way I've thought about keeping fit and healthy.

Like many, I'd imagine, it's another layer of fitness data that I really needed to get to grips with before it could have an impact. Counting steps and distance is pretty straightforward, but things begin to get more complicated when you start throwing heart rate into the mix.

The latest is heart rate variability. Something that has been introduced to the Fitbit Charge 2 through its new Relax app. The new fitness tracker takes real-time heart rate measurements to measure HRV to help you get the most out of your breathing.

Read this: Fitbit Charge 2 review

After Logitech decided to buy JayBird recently, I remembered about the JayBird Reign fitness tracker, sitting in the office cupboard. Its key feature is the ability to monitor heart rate variability. That's something you can't do on most fitness trackers.

I hold my hands up and admit to not really knowing why that was such a valuable piece of data to be able to glance at everyday. So I hit the books (did some Googling) and now I have a much better idea of why HRV tracking is important and why I hope it will make it onto more wearables in the future.

What exactly is heart rate variability?

So here's a breakdown of heart rate variability. Every heart rate varies and so with HRV, it relates to the measurement of the time interval between heartbeats. Unlike measuring heart rate, which is about the average number of heart beats per minute, HRV focuses on the small fluctuations of the heart. Now those fluctuations can be affected by a whole host of things. According to Polar, that could be age, body position, the time of day and health status. A whole host of mental, physical and emotional experiences can impact on HRV.

Why is it useful to measure or monitor it? Well, for fitness particularly, it's a way of knowing when you're putting to much strain on your body and can be an indicator of whether you're physically and mentally ready to work out again.

So if you're a runner and you've just put in a 2 hour run, it'll be able to help you decide whether you're ready to go again the following day or whether you should take the day off from training. When you're working out, your HRV decreases as you heart rate and exercise intensity rises.

Measuring HRV

In the case of the Jaybird Reign, it's all about recovery. It uses an optical heart rate sensor and a method of taking measurements that you'll also find with a host of HRV monitoring apps like HRV4Training and IThlete for instance.

These readings are always taken in the morning and there's a very good reason for that. That's because the it minimises the variables (stresses) that could impact on the data. That could be running around trying to sort the kids out for school or sitting in traffic for hours.

I put two fingers on top of the Reign's sensor for exactly two minutes and it counts down before delivering me a score and a verdict on whether I'm free to squeeze in a workout during the day. This idea of a perfect HRV score varies for every individual but it's commonly understood that higher is better. Ideally a score above 70 is good. Below that is not great but that doesn't necessarily mean you have to take a day off from the gym.

I scored a 40 but, as the image above shows, the app still suggested I still had enough in the tank to be active. I didn't get enough sleep that night and didn't get in the run I'd intended to, do but did manage a weights session instead.


Over the course of a few weeks, the Reign app would tell me when to take a break on occasions, and while I'd question some of the measurements, it did feel useful to have that data to hand.

I wanted to know how I could improve my HRV and it was no surprise to find out that improving diet, getting the full 8 hours of sleep and generally reducing the stresses in your life definitely help. In the case of exercise, it did help me appreciate that taking a day off is fine and you can still see positive changes in the long run.

The Jaybird Reign is by no means the perfect fitness tracker but I did see value in the ability to measure heart rate variability. It's definitely good news that Fitbit has introduced it to its latest wearable line and I really do hope it's a feature that other next-gen trackers packing heart rate sensors decide to embrace in a big way too.

5 Comments

  • Ryan says:

    Great article Michael. HRV can also be used to measure general stress levels as well. Caeden is launching a product that uses HRV to quantify stress levels, along with a mobile app that takes people through controlled breathing exercises to reduce stress levels. Another interesting use case for HRV beyond overtraining/undertraining. More info: http://www.caeden.com/collections/sona/

  • wiseupshop says:

    Great post. Thanks the information about HRV.

  • Samuel12 says:

    Great post! HRV can also be used for measuring overall heart heath. This will be particularly important to heart patients who need to change their lifestyle to improve their heart health (and prevent having another cardiac event). 

    One of the startups using HRV is Heartisans, who are developing a smart wearable with HRV tracking features. 

    Read more: www.heartisans.com

    Disclaimer: I work for Heartisans

  • Kristilsanders says:

    Great article! We have an HRV wearable company called REVITA5 www.revita5.com where we measure vitality over time!

  • JaneWelltory says:

    Looking forward to test Fitbit Charge 2 HRV. We have tried HRV from several hand wear trackers already (like Mio Fuse), but all of them still don't have enough quality of RR intervals in comparison with straps like Polar. 

    Data can be too dirty to calculate stress or current energy level (that's whet we do in Welltory app). So, will be great to test! 

    HRV can make wearables to the next level, because it's a true mirror of how you feel.

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