Depending how seriously you're taking your training, or what school of thought you're part of, having reliable data from one of the best heart rate monitors on the market can be invaluable.
That's because it'll allow you to control the intensity of your training to achieve your desired results, whether that's staying in Zone 2 for a low impact session or opting to take on some intervals.
While many of the best triathlon watches offer very accurate heart rate tracking, they still don't quite reach the high levels of accuracy you can get from many dedicated heart rate monitors, particularly during higher intensity sessions.
So, with that in mind, here's a selection of the best heart rate monitors for running and triathlon.
Best heart rate monitors for running and triathlon
Garmin HRM-Pro Plus
- RRP: £119.99 / $129.99
- Weight: 52g
- Battery life: 12 months (one hour of use per day)
- Connectivity: Bluetooth and ANT
Garmin’s HRM-Pro Plus is the upgrade over the HRM-Pro, but the only difference is around the battery unit.
That seems like marketing gone hyperbolic but it’s an important change for triathletes as the cover is more water secure than its older sibling.
This is damn useful as the Pro Plus stores swim heart-rate data, albeit it doesn’t stay quite as firmly in place as Garmin’s HRM-Swim, which features a wider strap.
When used as a standalone device, it records the basics of steps, all-day heart rate, calories burnt and intensity (in minutes).
With our Garmin Enduro strapped on, we tapped into a whole host of running metrics that are next level.
These include ground contact time and vertical oscillation which, granted, you might use sparingly out of interest more than anything else, but also power, which is becoming an increasingly popular run metric for triathletes.
The HRM-Pro Plus also calibrates for treadmill running by gauging stride patterns at different intensities when running outdoors.
It needs about two hours of pavement pounding to start calibration, which doesn’t need to be in one session.
The device supports Bluetooth and ANT and picked up our Zwift sessions quick-smart (which also means it links with other watches).
All in all, it’s very good, though costly for this genre of training tool.
Verdict: Impressive chest strap maximised by existing Garmin users.
Score: 82%
Polar H10 Heart Rate Monitor
- RRP: £76.50 / $89.95
- Weight: 60g
- Battery life: 400 hours of training
- Connectivity: Bluetooth and ANT
Designed to assist each triathlon discipline, this heart rate monitor from Polar promises particularly precise results to a swimming depth of 30m, though you'll probably have to transfer the data to your watch afterward, as Bluetooth doesn't transmit data in water.
The silicon strap is made with a slip-proof material to help stop it moving around when you're in the water, and it has 400 hours of battery, which means you can take in plenty of metrics to measure your performance over an extended period of time before needing to pop a new battery in.
Accuracy is very good indeed, while Bluetooth and ANT connectivity means you can use this monitor with many different devices.
Verdict: Reliable and comfortable. Read our full Polar H10 review for more.
Score: 86%
Polar Verity Sense
- RRP: £86.50 / $99.95
- Weight: 19g
- Battery life: 30 hours per charge
- Connectivity: Bluetooth and ANT
What’s the point of an arm-based heart rate monitor over a wrist-based monitor, you may ask? Well, there’s certainly anecdotal evidence from sport scientists who work with athletes that they feel it’s more accurate.
That’s significantly down to the compression you can enjoy with an arm strap compared to wrist alternative, which is the ideal when using an optical sensor.
We’ll come back to accuracy but more on the usability first. It has three modes – heart rate, record and swimming – that you switch between via one button, before slotting into the arm band.
Heart rate transmits your bpm to either the Polar Flow app on your smartphone or a compatible device, which are many as it has both Bluetooth and ANT connectivity. We synced it to our Polar Grit and it worked well.
The record feature does as it says: records the session, though this time in the Verity itself, which you can then download to the app afterwards. Simple.
And then there’s the swim mode, which is arguably the greatest sell to triathletes, though note that it’s for indoor swims only.
You choose the pool size on your Polar app and the Verity will do the rest, which really is about monitoring heart rate as it’s not about measuring factors like stroke rate.
It measures heart rate via a goggle clip and your pulsating temple, which we felt proved pretty accurate. Our slight ambivalence is it’s very hard to have a standard to compare against in the swim as it’s notoriously hard to measure.
As per many optical sensors, there’s a slight lag on tougher efforts, especially circuit training, but overall we were impressed. Whether you need an extra heart-rate tool in your armoury remains to be seen.
Verdict: A solid offering, though it might not appeal to all.
Score: 77%
Coros Heart Rate Monitor
- RRP: £69 / $79
- Weight: 19g
- Battery life: 38 hours per charge
- Connectivity: Bluetooth
We were in Bilbao earlier in 2023 for the Science & Cycling Conference and got speaking to acclaimed exercise physiologist Stephen Seiler.
The American, who now works out of Norway, extolled the precision of armband heart rate monitors over wrist-based optical ones.
That made sense, as wrapping the sensor around the fleshier upper arm is far more efficient to block out accuracy-inhibiting daylight than sensors that cling to your bony wrist. Hence, that’s one of the reasons you’d buy this sensor from Coros, albeit accuracy was middling.
Rather neatly, it has a ‘skin sensor’ that detects when it’s snug against your arm. Snug, it’s on; not snug, it’s off! The strap’s a hearty mix of polyester and nylon, and is extremely comfortable.
It’s lightweight and svelte so slips beneath your base layer nicely. Battery life’s around 38hrs, which is up there with its competitors, including arguably the market leader, the Polar Verity (reviewed above).
But it’s against straps like the Verity where the Coros falls short. You see, Coros’ remit is very tight: to broadcast heart rate to an accompanying watch or phone. (It’s Bluetooth, so connects to most watches and phones.)
And that’s it. Which is fine. But too tight a brief when you compare it to the Verity, which stores up to 600hrs of training data for download and subsequent analysis.
The latter also has a swim mode for recording heart rate, distance and pace. The Coros is waterproof, but that’s it – no swim mode.
All in all, it’s fine. But you’d struggle to make a case for it over the Verity, especially as they’re currently the same price.
Verdict: Solid training tool, but more comprehensive competitors out there.
Score: 70%
Wahoo Tickr Heart Rate Monitor
- RRP: £39.99 / $49.99
- Weight: 48g
- Battery life: 500 hours
- Connectivity: Bluetooth and ANT
If you'd prefer a heart rate monitor that sits outside the Garmin or Polar range, it's well worth considering the Tickr from Wahoo, particular if you have other devices from the brand already.
Made to clip on and take off with ease, it has a front snap fastener for simple access with a smooth and slimline design that shouldn't feel uncomfortable at any point of your workout.
Thanks to the LED lights that will flash on when it's in use, there'll be no confusion over whether you've actually turned it on either, so no nasty surprises and disappointments when you go to collect your data at the end of the event.
See our full Wahoo Tickr review for more.
Verdict: A handy, top value training tool for triathletes.
Score: 89%
Kalenji Dual ANT HRM
- £34.99 (UK only)
This slimline device from Kalenji will track all your essential training details while remaining comfortably on your body throughout your intense workouts, thanks to its soft strap.
It's water resistant, so while it's not ideal for swimming, it can withstand some sweat or splashes should the weather turn on your run. It will pair with devices such as your smartphone or triathlon watch via ANT+ or Bluetooth so you can take a closer look at your measurements.
It also has a clever eco-friendly design, with the promise that over 80% of issues that result in a break or fault can be repaired so you can hold onto your device for longer.
What to look for in a heart rate monitor
Accuracy
This is where chest straps continue to rule over the wrist-based heart rate monitors you'll find on triathlon watches.
Chest straps work by dampening the electrodes and pressing them against the skin, which then utilises electrocardiography to detect the heart’s electrical activity.
According to a 2017 study published in the Journal of Medicine and Sport and Exercise, the Polar H7 chest strap proved to be 99.6% accurate when compared to the gold standard of an ECG (electrocardiogram).
The same year, the Journal of American Medical Association Cardiology reported similar with chest straps showing a 99% correlation with an ECG.
These results compare favourably with their wrist-based siblings, which work via a method called photoplethysmography (PPG) to measure heart rate.
Essentially, this involves shining light through the skin to read fluctuations in bloodflow.
These are arguably more practical but less accurate as the results can be skewed by a variety of factors, including letting light into the sensor, skin tone and even moles.
A 2019 study published in the Journal of Sport Science found wrist-based accuracy varied between99% and 86.5%.
Comfort
Most chest straps score highly in the comfort stakes as, at their heart, they’re a soft, breathable, pliable fabric.
Where discomfort might strike is the sensor part. This tends to be a firmer strip of material because it’s cradling the chest sensors.
That’s understandable but, when it comes to comfort, a slightly more pliable material is what you’re after. A Polar H10 chest strap is a good example.
Also look out for the mechanism to clamp the strap in place, which tends to be a clasp or buttons. Just remember that you’ll need it tight enough to record an accurate reading but not so tight that it’s restrictive and uncomfortable.
The best heart rate monitor chest straps will retain their shape over time. Though some lose elasticity, which means they can start to slip down.
Connectivity
Chest-strap heart rate monitors are the data collectors. But you’ll need a watch or smartphone to display the information.
That’s where connectivity comes in, which is via Bluetooth or ANT+.
Historically, Polar relied solely on ANT+ connectivity but the rise of Bluetooth changed all that and now, like all the major HRM manufacturers, they’re Bluetooth applicable. In our experience, both are reliable.
Also note that the sensors employ coin-size batteries that’ll need changing over time.
What's the difference between cheap and expensive heart rate monitors?
The key difference between chest strap monitors is breadth of features.
The majority offer heart rate and might record the data for download later.
However, more expensive chest straps, like the Garmin HRM-Pro Plus, offer much more. This is one of the few chest-strap heart rate monitors to break the three-figure price barrier, which is justified by a suite of features that go beyond recording heart rate.
This includes running dynamics, which measures vertical oscillation, ground contact time, stride length, vertical ratio and more.
These metrics are designed to improve your run form and, vis-à-vis, run speed.
Just note that in the case of the Garmin HRM-Pro Plus you’ll need a Garmin device to display the running metrics.
More expensive chest-strap heart rate monitors tend to be lighter and more svelte, too, which is something to consider if you’re planning so slip yours beneath a form-fitting tri-suit.
Time to invest in a new watch to go alongside your heart rate monitor? Take a look at our list of the best triathlon watches.
Top image credit: Getty Images
