Wednesday, February 1, 2023

Apple Watch Heart Rate Variability

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What Is Hrv Good For

Measure heart rate variability (HRV) and stress using Apple Watch

The definition of HRV as stated by Harvard Health, is a measure of the variation in time between each heartbeat. Academic journals expand on this saying that the HRV measures changes in time intervals between interbeat intervals of consecutive heartbeats. It is an indicator of how resilient your heart is to changes and a proxy for heart health and stress levels.

If you have watched any movies or shows where a heart rate monitor shows up it may seem like the heart beat is a uniform pattern, but there are minor fluctuations in that rhythmic sound. It is dictated by a combination of your brain and nervous system and is influenced by everything from your diet and environment to sleep and external stressors. Because it touches on such an important part of the body, the heart, and because there are some many critical processes that can influence it changes in heart rate variability can be linked to a huge variety of wellness and health issues.

Hrv In The Apple Watch

Apple introduced HRV readings to the Apple Watch in WatchOS 4 back in 2018 and it remains available on their latest offering, the Apple Watch Series 7 . They are taken automatically, in the background, at suitable times. However, you can also manually collect HRV data by starting a Breathe session in the Mindfulness app.

You wont see the result when you finish the 1-minute breathing exercise, though. The data is ferried over to the Apple Health app. If you tap All Health Data from the apps home screen you should see an entry for Heart Rate Variability.

This takes you to a screen that shows your HRV over time, with optional timescales of a day, week, month, 6-month period or a year. Its a sensible way to relay the data, sitting outside of the regular fitness area and encouraging you to look at trends and averages, not single results.

What Is A Good Hrv Measurement

There are no absolutes when it comes to HRV, only individual trends.

In general, a higher HRV indicates that you are more relaxed and less stressed than a lower HRV does. However, what is an abnormally low HRV for one person can be a high one for someone else. Whoop, a manufacturer of heart rate trackers, has a useful graph on its site showing the middle 50% of values for people at different ages: Its quite a large range.

Instead, what youre looking for is changes in HRV. If your HRV drops lower over a few days, you might be more stressed than normal, not sleeping well, or even getting sick. Or, you could just be working out a bit too hard and needing to take a day or two off.

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Hrv In Garmin Watches

Garmin initially required you to use a chest strap for HRV readings, but not so anymore. With the release of 2021s Garmin Venu 2 we were introduced to Health Snapshot, a 2-minute relaxation mode that spits out a bunch of stats including HRV.

You can find this in Garmin watches with the Elevate v4 heart rate reader tech, like the Venu 2, Fenix 7 and Garmin Epix 2. Some older watches, like the Fenix 6, measure HRV in their stress test modes too.

Garmin opened up heart rate variability recording significantly in 2022. The Forerunner 955 and Forerunner 255 introduced HRV Status, which takes readings overnight and shows you the results as part of a morning report. It is a much more friendly and passive way to try out HRV monitoring. We hope to see these features come to other Garmin watches, like the Fenix 7, in future.

How To Improve Heart Rate Variability

How to make sense of your Apple Watch Heart Rate Variability (HRV) data ...

Methods for increasing HRV include the following:

Intelligent Training. Dont overdo it and push too hard for too many days without giving your body an opportunity to recover .

Hydration. The better hydrated you are, the easier it is for your blood to circulate and deliver oxygen and nutrients to your body. Aiming to drink close to one ounce of water per pound of bodyweight each day is a good goal.

Avoid Alcohol. One night of drinking potentially decreases HRV for up to five days.

Steady Healthy Diet. Poor nutrition has adverse effects on HRV, as does eating at unexpected times.

Quality Sleep. Its not just the amount of sleep you get that matters, but also the quality and consistency of your sleep. Going to bed and waking up at similar times each day is beneficial.

Auto-Regulation. In general, trying to get your body on a consistent schedule is helpful. Your body does things more efficiently when it knows whats coming.

Learn More: 10 Ways to Improve Your HRV

Also Check: How To Avoid Congestive Heart Failure

Other Apps And Devices That Calculate Hrv

If you want more information than simple HRV averages, there are several other apps that can take and analyze HRV, but you may need to pick up an external heart monitor to use them effectively.

The friendliest app out there for HRV tracking that I’ve found is Welltory it breaks down your HRV results into easily-readable areas like Performance , Energy , and Stress . For basic measurements, you don’t even need a proper passive electric chest strap you can use your iPhone’s rear camera instead .

The app is free to use for these basic measurements upgrade to a paid subscription, however, and you can access more detailed measurements from your HRV calculation .

It’s worth noting given all the privacy and political concerns of late that Welltory began as a Russian startup. That said, it’s currently based out of NY and has a pretty straight-forward privacy policy. Given that the data is analyzed on Welltory’s servers, however, I wanted to mention it.

HRV4Training also lets you use either your iPhone’s rear camera or an external heart monitor to measure your HRV, but the $8.99 app is designed specifically for the athletic crowd: It tracks the same metrics as Welltory, but uses a 30-day rolling scale to provide suggestions about your baseline and how you should train from day to day.

The $13.99 SweetBeat HRV uses slightly different formulas than Elite HRV, but has the same pros and cons .

What Should You Do Then

Despite the fact that no third-party app can control the Apple Watch or take an HRV reading, the Breathe app that comes with the Watch, consistently pushes HRV data to Health every time you use it.

Hence, you can, as a matter of fact, trigger an HRV reading using the Breathe app first thing in the morning, and disregard the rest of the data that is automatically collected.

Below we report more practical tips on how to take your measurement and interpret it with respect to your historical data, using HRV4Training.

Also Check: Acute Systolic Congestive Heart Failure

Improve Hrv Accuracy With More Regular Measurements

Some medical experts say measuring heart rate variability from a smart watch is not accurate. On the other hand, many do point to such tracking as being a good first step in making sure your heart health is where it should be. One important step to take, though, is to provide the Health app with plenty of data during consistent times.

Since you wont find anything on your watch that clearly says it will measure your heart rate variability, you will need to rely on other apps to do that for you. For example, the Mindfulness app will trigger data recording for heart rate variability.

Get into the habit of doing breathing exercises in Mindfulness at the same time each day. Open Mindfulness on your Watch and choose Breathe.

Whenever you do this, your Apple Watch automatically measures your heart rate, including your heart rate variability. This gives the Health app on your phone more measurements of your HRV while you are at rest. The more data points you give the health app, the more accurately it will reflect your cardio health.

How Does Heart Rate Variability Work

Heart rate variability and ECG charts from Apple Watch (30bpm to 207bpm)

Your heart beats at a specific rate at all times. That rate changes depending on what you’re doing at the time. Slower heart rates happen when you’re resting or relaxed, and faster rates happen when you’re active, stressed or when youre in danger. There is variability in your heart rate based on the needs of your body and your respiratory patterns. Certain medications and medical devices such as pacemakers can also affect your heart rate variability. Your heart rate variability also tends to decrease normally as you get older.

Whether youre awake or asleep, calm or stressed, your heart has to be able to react to changes in your life and surroundings. But it doesnt know when to react on its own, so it relies on another body system for help.

Parasympathetic vs sympathetic branches and heart rate variability

Your brain and nervous system support your heart. Your senses sight, sound, smell, taste and touch feed information to your brain about everything around you. Your brain has a direct line to your heart, telling your heart when it needs to speed up and work harder.

This direct line to your heart is your autonomic nervous system. This is a part of your brain and a set of nerves that operate without you thinking of them, even when youre asleep. Its divided into two main parts: your sympathetic nervous system and your parasympathetic nervous system.

In general, the sympathetic and parasympathetic nervous systems work like so:

Also Check: What To Do When Someone Having Heart Attack

View And Manage Detailed Heart Rate Variability Data

1. Go to the Apple Health app -> Browse tab -> Heart -> Heart Rate Variability.

2. Now, scroll down to the bottom. Here you should see different sections to manage your data:

  • Show All Data: Tap on it to dive into the details of your recorded HRV data. You can tap on the Edit option at the top right to delete specific data or get rid of all the data at once.
  • Data Sources & Access: It allows you to keep track of data sources and find out the apps that are allowed to read your data.
  • Show All Beat-to-Beat Measurements: As the name itself suggests, it lets you take a close look at all the beat-to-beat measurements.
  • Beat-to-Beat Measurement Data Sources and Access: It allows you to view the beat-to-beat measurement data sources and access.

How Does Apple Measure Heart Rate Variability

The Apple Watch measures HRV by monitoring the time interval variation between heartbeats. Your heart beats at different rhythms at different times when doing different things. Apple captures all this data using the heart rate sensor in the watch to deliver what is called a Standard Deviation of heart measurements. Many researchers have now identified that Apple Watch is very, very good at heart rate monitoring.

Read Also: Acute On Chronic Congestive Heart Failure

Hrv In Fitbit Watches

HRV got added to the best Fitbit watches in 2021. Its not too picky about the device you use, as Inspire, Fitbit Luxe, Fitbit Sense, Charge 4 and Versa 2/3 watches are compatible.

Readings are taken overnight, possibly spurring Garmin to bring us its HRV Status mode a year later. We havent found Fitbits HR accuracy to be quite as good as Apples, or that of the latest Garmin watches. But part of a good HRV algorithm deals in discarding faulty readings, so this may not impact Fitbits scores.

There is an issue, though. Fitbit keeps long-term stat monitoring behind a Fitbit Premium paywall. Its a subscription service that also unlocks guided workouts and nutrition plans. HRV stats are not particularly useful if your data only extends back a week, so if you want to monitor variability effectively youll need a Premium sub.

Heart Rate Variability: Rmssd

Best apps for tracking your HRV (heart rate variability) on iPhone

As features, we will look at rMSSD. rMSSD is a clear marker of parasympathetic activity and the main feature we use for our analysis in HRV4Training, similarly to what other apps do as well. The sports science community seems to have settled on this feature for several reasons. First, because of the clear physiological link, as mathematically rMSSD captures fast changes that are due to how the vagus nerve modulates heart rhythm, and secondly for practical reasons, as it is easy to acquire, easy to compute, less dependent on breathing rate, and reliable over short time windows and less controlled conditions.

You can find a few examples of how rMSSD changes in response to various stressors , in part 3 of our guide. This is an effective way to capture how stress affects your body and how long it takes to get back to normal.

Whatwe expect given the data above is to see extremely close values between the Polar H7 chest strap and Apple Watch data. For the plot below, I computed rMSSD for each time window:

Results are very good considering normal variation in physiology and limitations in data synchronization.

Recommended Reading: Women Having Heart Attacks

How To Use And Improve Your Hrv

Theres more to HRV than just idle curiosity. When you get used to looking at your HRV and you have established a baseline , you can then use it to help you decide what kind of workout you should do.

When you have a low HRV, that suggests your body is under some stress. Maybe you did an intense workout the previous day and your body is still recovering from it, in which case you have earned yourself a rest day.

When your HRV is higher than average, that might mean youre in top form and your body is ready for a more challenging workout like a HIIT session.

If youve been unwell from a cold, for example you might notice that your HRV is lower than usual, and it might be wise to hold off on exercise until it returns down to your normal level.

Remember that HRV is just one metric, and its not infallible. You should use it as an extra indicator of how you are doing. Obviously, if you feel like death warmed over, its not a great idea to do a workout however high your HRV might be.

Go Premium For An Enhanced Experience

Enjoy deeper insight at-a-glance with SleepWatch Premium. With Premium, your Sleeping HRV trends are colored based on how high or low your result is compared to your age group. Sleeping HRV decreases with age, so comparing your Sleeping HRV to others in your age group may indicate whether your internal biology is aging slower or faster than your age-matched peers. Knowing how your internal biology may be fairing today can help you make smarter lifestyle choices sooner rather than later.

With SleepWatch Premium, you can also see how much higher or lower your Sleeping HRV is compared to other users in your age group and compared to other users most like you. If you are not a Premium member yet, consider upgrading your account today to unlock these benefits.

Become a Premium Member Today

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Hrv In Samsung Watches

Samsung uses HRV in its Galaxy Watches, but does not currently let you see the data. It feeds into stress readings, much like Garmin’s old approach.

Third-party apps that claim to measure HRV are available from Samsungs Galaxy Store, but we cant speak to their accuracy. Still, if youre desperate to try out HRV tracking, it is at least somewhat possible with a watch like the Galaxy Watch 4.

What Is A Good Heart Rate Variability Level

Apple Watch: How to force an HRV measurement

In a nutshell, there is no real good or wrong HRV even though, at rest, a high HRV is considered a positive factor. When active, this is just the opposite.

Measuring the HRV is basically getting insight into how your Autonomic Nervous System regulates the autonomic process of the body.

The Whoop wearable and the Oura Ring have collected a huge dataset of HRV data. According to them, a normal HRV can fall anywhere between 20 and 200 msec in adults.

More than a specific value cast in stone, what matters is to check the evolution of the HRV over time. A decreasing HRV trend can mean that your body has difficulty coping with the daily stress and thus could become more prone to diseases.

When analyzing your HRV, always think longitudinally over the course of several days or weeks, and do not worry too much about a low HRV day. Especially if you had a party the previous night, studies showed that alcohol could impact Heart Rate variability for up to one week.

Recommended Reading: Sign And Symptoms Of Congestive Heart Failure

Track Your Heart Rate Variability On Apple Watch With Ease

Thats pretty much all you need to know to track heart rate variability on your Apple Watch. Thanks to its deep integration with the Health app on iPhone, its possible to check the beat-to-beat measurements of HRV. As someone who heavily relies on the Apple Watch to stay fit, I must say that the watchOS 8 device is accurate in terms of recording workouts and presenting in-depth insight into your progress. Whats your take on Apple Watch as a health and fitness device? Share your opinions in the comments section below.

Get More Value From Your Hrv Data

The sticking point is that Apple Watch and the iOS Health app dont give any recommendations or insights into your HRV data like Whoop or Oura.

Its useful to know an upward trending HRV is a good indication of overall health but what about more actionable insights?

Ive used the app Training Today and have been impressed with its recommendations. After allowing it to read your HRV data from the Health app, the app compares your current HRV to your baseline to make a recommendation like taking time for recovery, keep steady but listen to your body, or ready for peak performance.

Training Today calls it a readiness to train score and works on an easy-to-use, color-coded 0-10 scale. Ive found the recommendations to be a really helpful nudge to listen to what my body is telling me.

Training Today is a with in-app purchases to unlock all of the apps features.

Another similar third-party option is HRV4Trainging which runs $9.99 and gives a similar experience to Training Today.

If you happen to have a compatible Bluetooth or ANT heart rate monitor from Polar, Suunto, or others, Elite HRV is another iOS app that gives a more detailed and actionable experience.

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