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Best ways to monitor your heart rate with a smartwatch

How to get the most out of the heart-rate monitor on your Apple Watch, and other smartwatches and fitness trackers

Best ways to monitor your heart rate with a smartwatch

Wearables are getting serious about health, and the ability to track your heart rate is becoming the norm.

Long gone are the days when wearables – smartwatches and fitness trackers – were little more than souped-up pedometers.

Health and ‘wellness’ features, such as heart-rate monitoring, are now more of a priority for people buying wearables than sports and fitness features, says research company Mintel.

But why measure your heart rate? Can you rely on your wearable to track it accurately? Which wearables offer more sophisticated heart health features? And how can you use your wearable to get the best out of it? Read on to find out.

Or, head straight to all the best smartwatches from our tests to see which come out on top.

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Why monitor your heart rate?

If you have any concerns about your heart, you should, of course, see your doctor. Assuming your interest is more casual, a heart-rate-monitoring wearable can be a big help in helping you get the most from your workouts.

By monitoring your heart rate, you can make sure you’re pushing yourself hard enough during bouts of high-intensity exercise and recovering enough afterwards.

Longer term, keeping an eye on your heart-rate patterns can help you notice what may be causing spikes during everyday life and tell you a lot about your cardiovascular health.

Interested in other ways wearables can track health metrics? Read five ways wearables can help you stay healthy.

Wearables that collect data on your heart rate can also give you more accurate feedback on other aspects of your health – for example, your sleep, calorie burn, stress levels and VO2 max (an estimate of the maximum amount of oxygen that you use during exercise – and therefore, a measure of your aerobic fitness).

That’s not to say a wearable that tracks your heart rate accurately will track these other things accurately too per se, but it’s designed to.

Find out more about measuring blood oxygen in our guide to pulse oximeters and COVID.

Cheap fitness trackers for heart-rate monitoring

If you don’t want a smartwatch, and you’d rather just have something lightweight that you can slip on your wrist and forget about, there are plenty of fitness trackers offering heart rate monitoring.

Fitbit Charge 4 heart rate monitor (£108)

Fitbit Charge 4

At less than 26g, the Fitbit Charge 4 is lightweight enough to keep on your wrist day and night. The strap felt a little stiff at first, but became much more comfortable over time. 

It has nice set of heart rate monitoring features including 24/7 heart rate monitoring, Active Minutes (a measurement that combines data on your resting heart rate, workout heart rates and age) and the ability to tell you what zone you’re in: whether you’re in the fat-burning zone or not, for example.

The heart rate monitor works continuously in the background every second when you’re working out and every five seconds the rest of the time. Fitbit also says the 24/7 heart rate monitoring helps it to track calorie burn more accurately.

Huawei Band 4 Pro heart rate monitor (£45)

Huawei Band 4 Pro

For something cheaper, check out the Huawei Band 4 Pro. Its smart features are basic but it has a surprisingly good range of fitness features – of which heart rate monitoring is one – for such a cheap device.

It too will monitor your heart rate 24/7 and will show you for each workout graphs of your average heart rate, maximum heart rate and heart rate zone, and the tracker will buzz to warn you if your heart rate exceeds those values.

We do see big differences in how accurately wearables can measure your heart rate, though. Some manage this very poorly, or else only manage it in some conditions – for example, struggling during low-intensity exercise, but getting more accurate at higher intensities. These include wearables that are dirt cheap as well as those at the more expensive end of the market.

Apple Watch and other smartwatches with advanced heart rate features

Increasingly, wearables are coming with more advanced heart-rate features, including alerting you if they detect a symptom of a dangerous condition.

Taking a heart-rate reading with an Apple Watch

Apple is leading the way as the Apple Watch Series 4 was the first to offer ECG (electrocardiogram) readings directly from your wrist, via an electrical heart-rate sensor.

The sensor measures the electrical signals in your heart to check for atrial fibrillation, or AFib (irregular heart-rate rhythms), which puts you more at risk of stroke. You can download readings into a PDF to share with your doctor.

It also has an optical heart-rate sensor (light from the sensor penetrates the skin to estimate heart rate). This measures your heart rate throughout the day and calculates various metrics for you, including the average heart rate while you’re walking, your Heart Rate Variability (HRV) and heart rate during a workout, and Breathe (guided breathing) sessions.

You can also check your heart rate at any given moment by opening the Heart Rate app, and you can turn on the option to get notifications if your heart rate goes above or below a chosen beats per minute (BPM).

The Apple Watch Series 6 and Series 5 also offer all of these features, while earlier models have some, but not all (not the ECG feature, for example).

However, Apple Watches are also very expensive. Read our reviews of the latest Apple Watches – the Apple Watch Series 6 (from £379) and Apple Watch SE (from £269) – to see if they impressed us overall.

Or head to our page on Apple watches compared to see which, if any, is right for you.

Other smartwatches for tracking heart health

If you don’t want to spend that much, or you’re not an iPhone user, there are other watches available with heart health features.

Fitbit Sense smartwatch

The Fitbit Sense (£130) has a number of heart rate features to rival Apple. It has standard heart rate monitoring, it can take ECGs and it combines your heart rate data with skin temperature sensor readings to report on your stress levels.

The Withings Move ECG is the first analogue watch with an ECG feature – and, at £108, it costs a fair bit less than an Apple Watch. 

And the Withings Scanwatch (above; £208) is a hybrid smartwatch offering notifications for atypical heart rate, ECGs, detection for sleep apnoea (a condition in which your breathing stops and starts, often associated with high blood pressure, heart failure or a stroke).  

As we said before, these are not medical devices, so you shouldn’t rely on them to notice something. We asked Dr Heather Morgan, lecturer in applied health sciences at the University of Aberdeen and a specialist in digital health and fitness tracking, for her opinion.

‘It could be a great feature in helping to prevent stroke: there have been a few cases where the Apple Watch has picked up an issue as a ‘pre-screening’ tool and the number of inaccurate diagnoses seems low . But it’s not something you can use to track, monitor or manage a heart condition.

‘It tells you that you either have AFib or you don’t, but not what kind it is, or what treatment you might need. Medical advice is always required and, once a condition been diagnosed and is being medically managed, the feature is useless.’

They’re more like interesting toys for the worried well, you could say.

Specialist heart health wristwatches: Omron HeartGuide review

Some wearables go beyond this, making heart health their USP.

The Omron HeartGuide (£499) is one such device. It’s being marketed as the world’s first clinically validated wearable blood pressure monitor: it has clearance from the FDA – the US Food and Drug Administration.

It can monitor your blood pressure, steps, distance, calories and sleep, and it displays some (limited) notifications from your smartphone.  The HeartGuide can also measure your heart rate, but only when you ask it to measure your blood pressure.

As you’ll know if you already routinely measure your blood pressure, blood pressure and heart rate are two different indicators of heart health: heart rate is the number of times your heart beats per minute and blood pressure is the force of your blood moving through your blood vessels. So the Omron can’t tell you what your heart rate is during a workout. 

If you need to take your blood pressure often, you don’t need advanced smart features and you’re not particularly fashion-forward, then this could sound like a sensible (if expensive) purchase. It could also appeal if you suffer from ‘white coat syndrome’ in a clinical setting and want to see what your blood pressure is like in everyday life at home.

You’ll need nimble fingers to take it on and off, though, which you’ll need to do each time you want to do the washing up. It can survive being splashed with water while you wash your hands, if you’re careful, but it can’t survive being submerged in water. And it feels heavy and cumbersome, even on a sturdy male wrist. We tried the medium, the only size currently available – and we dread to think what a large would feel like.

Note that you shouldn’t use the Heart Guide if you’ve had a mastectomy. Traditional blood pressure monitors can carry similar warnings.

Also, you’ll need to check with your doctor how often across the day you should be checking your blood pressure. Omron says you shouldn’t do so more often than is necessary, in case of bruising. If you’re only going to do so once a twice a day, there’s no need to have something so weighty perpetually on your wrist.

See our initial thoughts on the Omron HeartGuide smartwatch.

If you’re primarily interested in monitoring your blood pressure, head to our blood pressure monitor reviews. We’ve tested a number of Omron blood pressure monitors, as well as those from other brands.

There are also a number of apps you can download from the app store, such as Qardio. You pair these with a blood pressure monitor to get stats on your smartwatch or smartphone, which acts as a dashboard or diary.

How to make sure you’re tracking your HR accurately

There are a few things you can do to give your wearable the best chance of tracking your heart rate accurately.

  • Make sure your smartwatch or tracker is sitting snugly but comfortably on your arm, with the sensors flat against your skin above the wrist bone
  • Keep the smartwatch or tracker clean (following the manufacturer instructions, to avoid damaging it). Sweat can also interfere with readings
  • If you have poor circulation or you just feel cold, warm up a little before taking a reading
  • Smoking or drinking alcohol before taking a measurement can cause your heart rate to differ from your normal readings. Try taking a measurement again later.

Tattoos and heart-rate sensors

A number of manufacturers also say that having tattooed wrists can interfere with heart-rate monitoring. Optical heart-rate sensors may be thrown off by the ink, pattern, and saturation of some tattoos, which block light from the sensor.

If you have one heavily tattooed wrist, wear your wearable on the other one if it’s clear for everyday use. In general, you should wear your smartwatch on the non-dominant hand, for greatest accuracy.

If both are tattooed, or you’re a serious sportsperson, use a chest belt.

Chest belts are usually more accurate than wrist-worn heart-rate monitors (whether worn on either hand).

However, you probably wouldn’t choose to wear a chest belt when resting or during low-intensity activity, such as pottering about the house. And, in any case, a chest belt will be more accurate when you’re working out than resting, because it needs humidity (sweat) to capture your heart’s electrical signals. 

Discover the most and least accurate smartwatches and fitness trackers for heart-rate monitoring, as well as tracking steps and distance. Or see all our smartwatch reviews and fitness tracker reviews.

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