Coros Heart Rate Monitor review: Armed with information

The Coros heart rate monitor is for people who don’t trust the reliability of the heart rate data coming from their sports watch, but also don’t like wearing a chest strap-style monitor to more accurately measure effort levels during HIIT classes and runs.

It joins the likes of the Polar Verity Sense, Wahoo Tickr Fit and the MyZone MZ-Switch in moving heart rate tracking to the arm and while Coros is in the name, you can use it with other Bluetooth sports watches, smartwatches and gym equipment that support external heart rate sensors.

It sits around the same price as the competition and takes a slightly different approach to design, but does it deliver where it matters most? Here’s my full review.

Design and comfort

• Weighs 19g
• Worn on bicep
• Water resistant up to 30 metres

The Coros heart rate monitor takes more design cues from armbands like the Wahoo Tickr Fit and Scosche Rhythm 24 as opposed to the dinkier (and more circular) Polar Verity Sense, matching up the optical-based monitor to a strap that’s made from a mix of polyester, nylon and spandex.

There’s a small velcro area to secure the strap and then you’ll need to pull it up to your bicep, with Coros saying it’ll work fine for arm sizes ranging from 19-32cm. I had no issues slipping it on and it also didn’t budge or cause any irritation during my testing. It is bigger than something like the Verity Sense but I’d say I prefer this slightly larger form factor, mainly because it makes it more difficult to misplace compared to Polar’s setup.

That optical sensor tracking heart rate in real time is made up of five LED lights and four photodetectors to ensure you get a reliable signal. Unlike using a wrist-based optical sensor, moving that same sort of technology higher up the arm gives the sensor array a better amount of blood flow to get heart rate data accuracy closer to a chest strap monitor. Coros doesn’t, however, specify how close it is to a chest strap in terms of matching that accuracy.

The Coros sensor is packed into a scratch-resistant casing to keep it looking box fresh and carries a waterproof rating that does make it suitable for being submerged in water up to 30 metres. It does have to be charged, of course, and does require a proprietary charging cable to do so, which is always slightly disappointing to discover.

Performance and battery life

• Up to 38 hours battery life
• Works with up to three Bluetooth devices at once
• Wear detection works well

The first nice thing to know about this armband monitor is that it offers what Coros refers to as wear detection, which basically means it recognises when you’re putting it on so the sensor can turn on and get ready to track. It’s worked every time I’ve used it and makes the process of using the monitor more effortless than similar-style monitors.

It uses Bluetooth connectivity to pair to devices and unlike Polar, Wahoo and Scosche armband monitors, it doesn’t include additional ANT+ connectivity, which is a shame. It also doesn’t have any sort of storage, so it’s really about replacing the heart rate data from a device that might deliver less accurate data.

It will let you use that Bluetooth connectivity to pair up to three compatible devices simultaneously making it ideal for indoor cyclists who want to hook up to multiple pieces of connected kit at the same time.

Like other heart rate monitors you can pair this one to most devices that support the ability to connect to external sensors. I’ve successfully paired it with watches from Garmin, Polar, Amazfit and Coros itself without issue, and I’ve also had no problems using it with connected rowing machines and fitness apps like Strava.

In terms of the accuracy of the sensor, I’ve been very satisfied with what it’s delivered on the whole. On runs, general gym workouts and paired to indoor equipment it held up very well against a Garmin HRM-Pro chest strap monitor. The true test, though, would be how it handled more high intensity exercise, which is where optical sensors, particularly wrist-based ones, tend to falter. I was happy to see that it tended to match up, or be 1-2 bpm out from a chest strap (screens included), which is a very good showing indeed.

Coros stats for HIIT exercise (right) vs Garmin HRM-Pro chest strap (left)

Coros stats for steady exercise (right) vs Garmin HRM-Pro chest strap (left)

In terms of battery life, Coros says it can last for up to 38 hours off a single charge with 80 days in standby mode. If you’re using it with a Coros watch then you can view battery status on the watch or in the Coros companion app.

I’d say those battery numbers add up. I’ve not had to charge it during my testing, using it on average for an hour’s worth of training at a time. When you’re running low, there’s an LED indicator on the monitor to give you a visual sign that it’s time to grab a charging cable – a cable that I definitely hoped would be a bit longer. When you do hit 0 per cent battery it also takes just under two hours to charge up to full again, so it’s not a snappy charger to say the least.

Verdict

The Coros heart rate monitor armband is easy to use, a good size and comfortable to wear. It delivers really good HR data when compared with a chest strap, based on my tests,s o if you can’t get on with wearing a chest strap and don’t necessarily care about that ANT+ support or the lack of onboard memory, this is a great heart rate monitor to consider.