The Apple Watch has attracted many users due to its health-monitoring features, especially the ability to track heart rate.

Apple's wearable can monitor your resting heart rate and alert you if it rises above a certain level - and the new Apple Watch Series 4 will add the ability to monitor for low rates and irregular rhythms, and (with the forthcoming launch of a separate app) to run ECG scans.

If you've been diagnosed with a heart condition such as cardiomyopathy (or, in my case, PPCM - Peripartum/Postpartum Cardiomyopathy), tachycardia or atrial fibrillation, you might be wondering whether the Apple Watch will be able to help you monitor your condition and help you stay healthy.

Even if you don't have a diagnosis, there have been cases of people whose lives have been saved because the Apple Watch detected a change in their heart rate that concerned them enough to seek the opinion of a doctor. Apple even highlighted such case studies in a video during its September 2017 launch keynote. Heart rate tracking is very much of interest to Apple.

But if you have a heart condition, will the Apple Watch help you monitor it, or will it just cause more concern? And is it reliable enough to place your life in the hands of a wrist watch?

The heart rate notifications that warn you if your heart rate goes above 120 bpm is available only on Apple Watch Series 1 or later, so if you have a first generation Apple Watch you won't be able to access all the heart rate tracking features. And you'll need to update to watchOS 4 or later too.

How to check your heart rate with Apple Watch

If your Apple Watch fulfils the criteria above it can display your current heart rate, resting heart rate and walking heart rate.

Your watch can also notify you if it detects a dramatic rise in your heart rate while you are inactive. By default it can alert you if heart rate goes above 120bpm despite being inactive for 10 minutes, although you can change the bpm at which you are alerted, or turn the feature off. We'll look at amending the settings here.

There are a few ways to see your current heart rate:

  • Press the Digital Crown on the side of the watch, scroll up or down until you see Heart Rate, and tap it.
  • Press the side button to view the dock containing your favourite apps (these can be most recently opened, or ones you have chosen to appear here). We explain how to add apps to the Dock here.
  • You can also access heart rate directly from the watch face if you've got the right complication. By default the Modular face, the Simple face, Motion, and the Kaleidoscope face offer a Heart Rate complication but you can also add the Heart Rate complication to other Watch Faces. We explain how to add Heart Rate to the Watch Face here.
  • Alternatively you can raise the Apple Watch and say "Hey, Siri, what's my heart rate?"

How do you view your heartbeat on Apple Watch?

You can watch your heart rate in real time if you open the Heart Rate app, or if you add Heart Rate to your watch face.

You can also view your current, resting rate and your walking average.

How to use an ECG on Apple Watch

The Apple Watch Series 4, which has electrodes in the Digital Crown dial and new electric heart sensors in the underside, is therefore able to offer an ECG function - although this won't be available until the launch of a separate ECG app later in 2018.

Once this is available, you'll be able to trigger the ECG by placing a finger on the Digital Crown. A circuit will be completed across your body, from fingertip on one hand to the wrist on the other, and the watch will thereby take an ECG reading.

Make sure you update to iOS 14.3 to get Apple's new and more accurate ECG app.

How to add the heart rate to your watch face

You can add a Heart Rate complication to your watch Face. Some watch faces include Heart Rate by default while you can add it to others in the customisation settings. Some Watch faces can't accept complications unfortunately.

The Modular face, the Simple face, Motion, or the Kaleidoscope face all offer Heart Rate as a default option.

However, you can add Heart Rate to many other watch faces, assuming they have Complications as an option. You can do so in the Watch app on the iPhone or on the Watch itself:

In the Watch app on your iPhone:

  1. Open My Watch and choose a Face from those available.
  2. (If you don't see a Face you like you can create one on the Watch, here's how).
  3. Tap on that Face to be taken to the edit options.
  4. Swipe down the page and if Complications are available you will see them.
  5. There may be more than one position available for Complications, choose the location that you'd like the Heart Rate Complication to live (if you have the option of more than one).
  6. Scroll through the list until you find Heart Rate.
  7. Scroll down and choose Set as current Watch Face.

How to measure heart rate on an Apple Watch

On your watch:

  1. Press on the current watch face.
  2. Find the face you like and tap on Customise.
  3. The areas where you can add Complications will be highlighted, tap on one.
  4. Scroll through the options using the Digital Crown.

Now when you wish to see your Heart Rate you need only tap on the Heart symbol on the Watch Face, or if the Heart Rate is displayed you will see it as it was when it was last recorded (every ten minutes as standard).

Some Watch Faces allow you to display more than just the heart icon, in many you can see the whole BPM and when it was last taken.

How to add the Heart Rate app to the Dock

To add the Heart Rate app to the Dock on your Apple Watch:

  1. To access the Dock press the side button on the Watch (the one below the Digital Crown).
  2. If the Heart Rate app is present already it will appear here (you can set it to sort by Recents or Favourites so it may be there if you have been using it).
  3. If you don't see it in the Dock, you can add it by opening the Watch app on your iPhone and choosing My Watch > Dock > Favourites and adding Heart Rate to the list if it isn't already there.
  4. You can edit the list so that fewer apps are in it by tapping on the red spot beside any you wish to delegate, or change the order by pressing on the lines to the right of the app name and dragging it up or down the list.

How to find out what your Heart Rate was in a workout

When you are using the Workout app your Watch will monitor your heart rate continuously during and for three minutes after your workout.

After your Workout you can view the stats on the Watch:

  1. Open the Heart Rate app on the Watch.
  2. Scroll to the Activity and you can see the average BPM.
  3. If you'd like to find out more press and hold on the Activity until it takes you to a page showing a graph, here you will see your High as well as information about your recovery.

You can also view the information on your iPhone:

  1. Open the Health app on your iPhone.
  2. Tap on Heart Rate.
  3. Swipe across until you find your Workout.

How to change the BPM that you are alerted at

When you start up the Heart Rate app for the first time you get the option to turn on a feature that will alert you if your heart rate rises above 120 bpm if you have been inactive for 10 minutes (it won't alert you in the middle of exercising).

If you want to keep an eye on your heart rate turn this on.

The default is 120bpm, but you can set a threshold between 100 and 150 beats per minute. Here's how:

  1. Open the Watch app on your iPhone.
  2. Tap on My Watch.
  3. Tap on Heart Rate.
  4. Tap on the number next to Elevated Heart Rate and choose the heart rate at which you wish to be notified.

Could an alert go off in a scary movie? On a fairground ride?

It shouldn't go off unless the heart rate is still above 120bpm after ten minutes. The watch will keep monitoring to see if the rate stays elevated.

After you run for a bus, an algorithm will check the rate when you've been still for a little while.

How does the Apple Watch measure your heart rate?

The watch has two ways of measuring your heart rate. Depending on whether you're active or not, the watch will uses a green light or an infrared light.

When you're active, such as during a workout, the watch checks your heart rate by shining a green light on to your wrist. Because your blood is red it absorbs green light, so when the green light is shone on your wrist your watch is able to detect whether there is more or less blood flow. There will be more blood every time your heart beats, therefore your watch can gauge how rapidly your heart is beating.

How to measure heart rate on an Apple Watch

The green lights are also used in Breathe sessions, to calculate walking average and Heart Rate Variability, and if you trigger the heart rate app to take your heart rate.

More power efficient infrared lights are used to obtain heart rate data at ten minute intervals throughout the day.

The sensor in the Watch can detect between 30 and 210 beats per minute.

How to check blood pressure on the Apple Watch

While the watch can't check your blood pressure you can link it to various apps and equipment that can do so.

From the Health App on the iPhone choose Health Data, Blood Pressure.

The following apps can be used to Track Blood Pressure:

  • QardioArm blood pressure monitor with the Qardio heart health app.
  • Withings' Wireless Blood Pressure Monitor with its companion iPhone app.

The health app on your iPhone can take data you input, data gathered by your watch, and data gathered by peripherals and third-party apps.

How accurate is the Apple Watch heart-rate monitor?

Apple notes that "some anomalies may appear in the displayed data, resulting in occasional heart rate measurements that are abnormally high or low." Every now and then you may see an odd figure - this doesn't necessarily mean that there is anything wrong.

Apple has some advice for improving accuracy. It suggests that you:

  • Make sure that your watch is a good fit. It should be "snug but comfortable", according to Apple.
  • Apple also recommends keeping your Apple Watch and bands - and your skin - clean and dry.
  • If it's cold there might be less blood flow, which could affect the reading.
  • If you have a tattoo the ink could block light from the sensor.
  • Irregular movements can affect the sensor - you might get a better reading when running than when playing tennis for example.
  • We'd recommend allowing your watch some time to gather data before relying on the information.

Apple recommends that if you can't get a consistent reading you should connect your watch to an external heart rate monitor.

As for how accurate the Apple Watch is at measuring your heart rate, medical research seems to suggest it at least reasonably accurate:

A study, published in JAMA Cardiology in October 2016, tested the Apple Watch, Fitbit Charge HR, Basis Peak and Mio Alpha wristbands and found that the Apple Watch and Mio Fuse performed the best, with about 91 percent accuracy while the others fell below 80 percent accuracy.

Scientists at Stanford have also claimed that the Apple Watch is the most accurate of six wrist-worn trackers tested (including the Samsung Gear 2, MIO Alpha 2, PulseOn, Microsoft Band, Fitbit Surge, and Basis Peak). Apparently the Apple Watch had the smallest margin of error (2%) out of the devices tested.

In addition, SonoPlot founder Brad Larson compared an Apple Watch to a dedicated heart-rate monitor and found that the results were identical.

However, if accuracy is important, perhaps you are cardiac patients who needs to keep your heart rates within a certain range, you may need a medical-quality chest-strap monitor.

How to view your heart rate data

You can view Health Data in the Health app on your iPhone:

  • Open Health.
  • Tap on Health Data.
  • Tap on Heart.

Here you can view you Heart Rate high and low, Resting Rate, Walking Average, Workout, Breathe, and Elevated Heart Rate Notifications.

You can also check Heart Rate Variability, which measures the variation in time intervals between one heart beat and the next. We explain this in more detail below.

You'll get more accurate date after you have been using the watch to monitor your heart rate for a while.

What is Heart Rate Variability on the Apple Watch?

The ability to measure Heart Rate Variability (HRV) may be important to you if you have an arrhythmia.

HRV indicates the fluctuations of heart rate around an average heart rate.

The higher the score the better - it's a marker of how well your body can bounce back after a stressful situation, so the fitter you are the higher the score is likely to be.

A low HRV could suggest stress or inflammation. But HDR can also decrease with age - so don't compare yourself to someone else. It's the trend over time that is important here.

What is a normal heart rate?

According to the Mayo Clinic, a normal resting heart rate can anything between 60 and 100bmp, although the lower the number the more efficient the heart function and the better the cardiovascular fitness.

Can the Apple Watch be used to detect heart conditions

During Apple's presentation of the newest Apple Watch during the 9 September keynote the company showcased a number of examples.

It seems that every week another story breaks about someone whose life has been saved by the Apple Watch.

The Watch has detected pulmonary embolism, blood clots on the lungs, as per this Telegraph article.

In this case a Macworld US contributor outlined how his watch alerted him to blood clots in his leg.

In another case a builder was rushed to hospital after his watch detected an abnormal heart rate of 210bpm: a sign he was having a heart attack.

And here is a case of someone whose atrial fibrillation was detected by the Apple Watch, allowing him to avoid a stroke.

Apple has announced a partnership with Stanford for The Apple Heart Study. The study will use data from the Apple Watch to monitor arrhythmia (irregular heart rhythms, including those from potentially serious heart conditions like atrial fibrillation). You can participate in the study with Stanford by downloading an app from the App Store. Information on how to participate will be posted here.

Update January 2021: Interestingly, a study has shown that the Apple Watch can detect COVID-19 before you know you have it

So should you use your Apple Watch to monitor your heart?

The data gathered by your Apple Watch might not be accurate enough to make a diagnosis, but it does seem to be accurate enough for at-home screening and to warn people if they are at risk.

If you're at all concerned about your heart health, we'd recommend using the Apple Watch. But a diagnosis would have to come from a doctor's office, obviously.

In other news, Apple's patented a way to measure Blood Pressure from the wrist - read about that here: Apple patents way to measure blood pressure from wrist.

There are reports, as of January 2020, that the iPhone 12 can interfere with pacemakers. Read: iPhone 12 MagSafe can interfere with pacemakers.