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Heart rate monitors

The Best Heart Rate Monitors Of 2021

Keen on tracking your ticker? Here are the best heart rate trackers to gauge your health or guide your training

Nick Harris-Fry
30 Nov 2021
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Steps once reigned supreme as the go-to metric for fitness trackers, but nowadays heart rate monitoring has become the fundamental feature. It’s a welcome development (although we still think 10,000 steps is a worthwhile goal) because tracking your heart rate allows you to see how hard you’ve pushed yourself in an individual workout by the time spent in each heart rate zone. Most trackers will also provide a measure of your overall fitness over time through your resting heart rate or an estimate of your VO2 max. And 24/7 heart rate tracking can monitor your progress towards the target of 150 minutes of moderate cardio activity a week, approved by the NHS and the World Health Organisation.

These features are appearing on more trackers than ever before, but you won’t find heart rate monitors only on the back of wrist-worn devices. There are also dedicated heart rate trackers available which are worn around your arm or chest.

Of the three places on your body you can wear them, the chest is your best bet if accuracy during a workout is key for you – if you’re doing a HIIT session (either in the gym or an interval run as part of a training plan) or basing your training around heart rate, for example. The readings from chest strap monitors are taken via electrodes, and are more reliable and recognise changes faster than those you get from wrist and armband trackers.

Wrist trackers are more comfortable and convenient to wear, though, and by keeping them on at all times you’ll get info on your resting heart rate – a very helpful measure of your general cardiovascular health – plus more in-depth sleep tracking. Newer fitness trackers are also improving their accuracy during workouts, especially if you have a light, small device that sits snugly against the wrist and have the advantage of a screen to show you how hard your heart’s working. More advanced multi-sport GPS devices can also guide you through heart rate-based workouts.

Some wrist trackers are also now able to use their heart rate monitor to take a medical-grade electrocardiogram measurement from the wrist. This can detect atrial fibrillation – an irregular heartbeat, which is a condition that’s worth getting checked out by a doctor if your device spots it. Trackers need a CE mark to be certified as medical devices in the UK to take an ECG, and only a handful have done this, including the Apple Watch, Withings ScanWatch and Fitbit Sense.

Armband trackers sit between wrist and chest strap monitors. They are optical heart rate monitors, like fitness trackers, but by positioning them on your forearm, upper arm or even around your thigh, you get a more reliable reading than on the wrist. They’re easier to slip on than a chest tracker and generally they are as accurate, but you don’t wear them outside of workouts so you can’t gain the benefits of knowing your resting heart rate or improved sleep tracking.

To help you decide which type and model of heart rate monitor best suits your needs, we’ve chosen the best heart rate monitors out there and outlined what they’re best for.

The Best Heart Rate Monitors

1. Best For Everyday Health Tracking: Fitbit Inspire 2


RRP £89.99

Fitbit epitomises the change in fitness tracking from steps to heart rate, with all but one device in the brand’s current line-up including an optical heart rate monitor. All of Fitbit’s best features are linked to the HRM as well, taking the heart rate information it tracks around the clock and using it to provide easy-to-understand insights into your health and fitness.

In the partner app you can view your resting heart rate over time, which is a solid indication of whether you are getting fitter – you want that number to go down – and also your Cardio Fitness Score. This is Fitbit’s equivalent of a VO2 max measurement and another useful stat that shows your general cardiovascular fitness. In this case, you want the number to go up over time. The HRM also feeds into Fitbit’s sleep tracking, and for both your slumber and Cardio Fitness Score, your numbers are compared with those of other Fitbit users of your age and sex, so you can see how you stack up.

In 2020 Fitbit debuted Active Zone Minutes which clearly tracks your progress towards the weekly target of 150 minutes of moderate cardio.


Time spent in high heart rate zones, as when running, counts double, but Fitbits will also automatically log every time your heart rate moves into a slightly higher heart rate zone, when you’re walking to the shops for instance, and add that to your tally. It also breaks the 150 minutes into 22-minute daily chunks, which helps to make it feel more achievable.

We recommend the Inspire 2 because it’s the cheapest Fitbit with Active Zone Minutes, and it’s great value at under £100. If you’re a committed exerciser, however, you’ll be better served by the Charge 4 (£129.99), which has a larger body and a thicker strap, and which we found tends to return more accurate readings when you’re working up a sweat.

Buy from Fitbit | £89.99

2. Best For Guided Training: Polar Ignite


RRP £174.50 | Polar Ignite review

The Ignite’s slender design means that it’s easy to get a snug fit against your wrist, which results in accurate heart rate tracking even during high-intensity activities, but it’s what Polar does with that data that makes the Ignite stand out.

This starts with the running event training plans offered through the Polar Flow website and app, designed to improve your fitness and speed. Workouts based on heart rate sync to the device for you to follow.

However, it’s at night when the Ignite really comes into its own. It uses its heart rate monitor to track your heart rate and heart rate variability, which is a useful measure of how physically stressed your body is, to record how well you’ve actually recovered during your sleep. The next morning you’re given a rating of how well you’ve slept and how well your autonomic nervous system has recovered, which leads to recommendations for workouts based on your actual readiness to train that day.

Even outside of these features, the Ignite is a solid all-round sports watch that’s one of the very best available under £200. If you’re keen for insight into how you can use heart rate to shape your training it’s undoubtedly your best bet.

Buy from Polar | £174.50

3. Best For Advanced Features: Apple Watch Series 6


RRP From £379 | Apple Watch Series 6 review

Early versions of the Apple Watch were undermined by inaccurate heart rate tracking, but from the Series 4 onwards it carried one of the best wrist-worn sensors. The Apple Watch now tracks heart rate accurately throughout the day and during exercise, even if you do a HIIT session where your heart rate should rise and fall rapidly.

With this new sensor came the ability to take medical-grade electrocardiogram (ECG) measurements, taken by resting a finger tip against the button on the side of the watch for 30 seconds. It can detect signs of atrial fibrillation (irregular heartbeat), a condition which should also prompt a visit to your GP to get a proper medical diagnosis.

The watch will also alert you if your heart rate is abnormally high or low during the day or night, and again, if you’re getting these alerts frequently it’s worth going to the doctor with that info in case it’s a sign of something serious.

Along with these detailed health stats, the Apple Watch will estimate your resting heart rate and VO2 max, both good indicators of your overall cardiovascular fitness, and track how quickly your heart rate returns to normal after strenuous exercise – that recovery time being another good measure of your fitness.

Buy from Apple | From £379

4. Best All-Round Chest Strap: Polar H10


RRP £79.50

The H10 is accurate, comfortable and able to connect to two devices at the same time via Bluetooth, ANT+ and 5kHz, with the latter meaning it can be used for swimming. The battery lasts 400 hours before it needs to be replaced, which means even keen athletes will get through most of a year before having to replace it (a CR2025 replacement costs a couple of quid).

It’s also the most comfortable chest strap we’ve worn, a consideration that shouldn’t be underestimated. We found the buckle-like attachment better than the usual slip and loop you get on chest straps, and haven’t had any skin irritation from the H10 while using it for runs every day for months.

Buy from Polar | £79.50

5. Most Versatile: MyZone MZ-Switch


RRP £139.99 | MyZone MZ-Switch review

The MZ-Switch lives up to its name by being able to track your heart rate from your wrist, arm or chest. It contains an ECG sensor for measurements on the chest – the most accurate position – plus an optical PPG sensor for tracking from your arm or wrist, which many find more comfortable and convenient than a chest strap.

Wherever you wear it, you’ll be earning MyZone Effort Points (MEPs) during your exercise, and these are being earned at a faster rate when you’re working in higher heart rate zones. It’s another way to motivate yourself during HIIT sessions in particular, and some gym chains have partnered with MyZone to broadcast your heart rate and zone to screens during classes to help you work at the right intensity.

The MZ-Switch also boasts an impressive battery life for such a small, rechargeable device, lasting three to six months (the optical sensor uses more battery than the ECG). It connects easily to any device via ANT+ or Bluetooth, and swapping the sensor between the included straps for your chest, wrist and arm is a doddle.

The only real downside here is the price – it’s more cost-effective to buy a separate arm and chest strap tracker if you don’t plan on using the MyZone app and earning those MEPs.

Buy from MyZone | £139.99

6. Best Arm Strap: Polar Verity Sense


RRP £79.50

Our previous favourite arm strap HRM was the Polar OH1, and the Verity Sense is a straightforward upgrade. The battery life is longer at 20 hours (vs 12), the Bluetooth range is twice as big at 150m, it has a bigger memory for storing workouts, and it’s also waterproof to 50m, compared with the 30m of the OH1. The Verity Sense also comes with a clip so you can attach it to your goggles for measurements in the water.

Arm straps offer more accuracy than a wrist-based monitor while being more convenient and comfortable than a chest strap. The Verity Sense slips on easily and in our tests we found it impressively close to a chest strap’s readings in running, strength and cycling sessions.

It connects via both ANT+ and Bluetooth, and the lights system on the device shows the three training modes available. The first is for when you want to pair it to a device like a watch, the second is for recording a workout directly on the Verity Sense itself (which links to Polar’s Flow app to show your readings), and the third is a swimming mode.

Buy from Polar | £79.50

8. Best For Runners And Triathletes: Garmin HRM-Pro


RRP £119.99

If you’re a keen sportsperson the HRM-Pro is the best heart rate chest strap you can get, especially if you already have a Garmin device to link it to. It doesn’t come cheap, but the strap tracks a variety of extra running stats and works in the water, storing your heart rate data from swims to then transmit to the activity record from your Garmin once you’ve finished (Bluetooth does not work well, if at all, under water).

For runners the HRM-Pro records technique stats like ground contact time and vertical oscillation, and if you have a compatible Garmin watch you can see these stats live during your run. Many of them are even colour-coded to let you know what’s good, so you can work on improving your technique without having to focus on individual numbers.

Buy from Garmin | £119.99

9. Best Under £50: Wahoo TICKR


RRP £39.99

Wahoo has recently updated its popular TICKR heart rate monitors: both the standard TICKR and the TICKR X have seen an increase of almost 50% in the life of the CR2032 coin battery they use. That’s up to 500 hours – you’ll have to be an elite athlete to get through that in a year. The more expensive TICKR X (£64.99) adds running dynamics stats like vertical oscillation and ground contact time, but if you don’t feel the need for those extras then stick with the cheaper TICKR, which offers tremendous value. It can connect via ANT+ and Bluetooth, and can be paired with up to three Bluetooth devices at once.

Buy from Wahoo | £39.99

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