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Polar A370 Review – 24×7 Optical Heart and Sleep tracking

When the Polar A360 debuted in 2015, I wasn’t very impressed with the devices optical HRM- However, in the last two years Polar has released a slew of devices with optical heart rate tracking, and have polished their firmware considerably. So with the new Polar A370, has Polar managed to bring the substance to match their activity trackers style, or is the A370 surviving largely on looks alone? Let’s find out!

Polar A370 Review – 24×7 Optical Heart and Sleep tracking

The Polar A360 was Polar’s first device to carry optical heart rate monitoring. The original review device I received certainly supported that the A360 was generation one software if not hardware. The A360 was a product I dearly wanted to like, felt very much let down by when it came to the headline feature – optical HRM

Since the A360, Polar has launched a series of trackers and watches with great optical heart rate sensors, such as the Polar M600 smart watch, and the Polar M430 (which has the award for my favourite running specific watch so far) showing that Polar really have a handle on their optical heart rate tech… Garmin Fenix 5 pay note!


This year Polar have updated their device with the A370, same gorgeous looks, but now with a few tweaks under the skin – namely better heart rate monitoring, expanded to 24×7 tracking, advanced sleep metrics, and as with the Polar M430, the ability to broadcast optical HR data over Bluetooth. With that in mind, let’s take a good look at the companies new activity tracker in the Polar A370 review!

The Device

Polar draws attention to their colour touch screen right on the box, along with the sleep and HRM features. Whilst the Polar A370 still has a beautiful OLED screen it, is not quite the game change it was as OLED screens have become more common in the sports device world

Polar A370

The Polar A370 remains a very classy looking device, but at the same time not in an over stylish way. The Garmin Fenix 5 and the Fitbit Blaze allow you to easily change straps for different settings, the Polar A370, in black at least, looks good down at the pub, or in the office.

Polar A370

Although there are a range fo six different colours if you wanted to have something a little more daring than black


So what do you get in the box for your £160? Very little is appears, you’ve the got the A370 itself, the paper manual and a USB charge cable. In fact, the box almost seems a little large for the contents!


Looking at the Polar A370 itself, the strap is easily removable if you wanted to swap out to one of the more daring colours. It is at this point that you really get the impression that the Polar A370 isn’t so much of a watch, but a small device that sits in a strap.

Polar A370

That said the process of actually removing the strap could feel a little alarming; you have to “break” the device out of the strap. I always feel that I’m going to over do it

This is something you have to get used to, well, not removing the whole device from the strap, but certainly cracking one end open the cover on the USB port to charge the unit. A port that is internally waterproofed to 30m allowing you to take the Polar A370 swimming

Although the USB port is waterproofed, when you plug the unit in, you do get a brief warning to remind you NOT to charge the unit when the port/unit is wet or sweaty. It is also worth while highlighting that the cover on my unit disappeared after about 3 weeks, as it is relatively easy to knock off when you grab the unit carelessly from charging – which you’ll be doing every 4-5 days – it would have been a real win if Polar had managed to stretch the battery to a week with this update!

The slightly odd thing is that Polar have removed the USB port from the Polar M430, due to issues with corrosion over time. So it is interesting to see that the micro USB port has been maintained on the new Polar A370.


That said, there are a few subtle changes visually between the two units, most clearly that the Polar A370 has a buckle closure, and textured strap, while the A360 had a smooth strap and a push stud closure. While the buckle may be more secure, I did think that the push closure actually looked more stylish!

Continuing to look round the unit, on the LEFT side is a small button, under the rubber, which can be used to wake the Polar A370

Polar A370

The Polar A370 is actually held within the rubber strap by two pieces of hard plastic and two thin bands of rubber which run along the two indentations either side of the device

Polar A370
The when the Polar A370 body clicks into these ends, it fits very firmly. Some what reflected, by my feeling I’m going to put too much pressure on the device when I take the off the strap! Certainly, I’ve no concerns that it would fall out on the run etc.

The screen on Polar A360 is gorgeous. Beautiful colour saturation, response to touch, well animated. One thing that has been clear from the Polar M400 onwards, Polar knows how to choose the best screens for their devices.

Polar A370

Although the OLED screen does look stunning inside, although it can be a bit harder to see on a nice day!

Polar A370

Certainly looking at the appearance of the Polar A370 you can see the “genetic” resemblance to the Polar Loop 2

Polar A370

Finally, on the bottom on the Polar A370, we have the optical heart rate sensor, unchanged from the A360, but also quite dissimilar from the newer circular units on the Polar M430 and M600, featuring two green LEDs, as opposed to their 6



  • Weight: 31.7g
  • Screen Resolution: 80 x 160 touch screen
  • Communication: BlueTooth
  • Smart notifications: yes
  • Sensors:
    • Optical Heart rate
    • Accelerometer
    • GPS dependent on phone – NOT on the unit
  • Battery:
    • 110mAh
    • Four days 24×7 heart rate tracking, if 1-hour use per day
  • Waterproofing: 30 m
  • Activities: Any activity available on Polar Flow can be uploaded
    • Sleep plus tracking
    • Steps and distance
    • Inactivity alert

Polar A370 Manual

The manual for the A370 is available from HERE

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Using the Polar A370

As with every sports watch, today first stop is to download the corresponding app. In the case of the Polar A370, you are looking for Polar Flow – Here for iOS and Here from the Google Play store.


You’ll still need to sign up to Polar Flow, in order to get access and more importantly download the latest updates for the watch before you use it for the first time

It’s really worthwhile pointing out two things, i) Polar is very honest about their estimated sync/update times ii) sync/updates can be a little slow if it says 15 mins, it means 15 mins. Go and grab a coffee


Given the beautiful screen is so bright, its off by default, but the unit responds when you raise your wrist up and instantly powers on – well most of the time!


I found that if you have not told the Polar Flow software correctly which wrist you are wearing it on, the accelerometer doesn’t always play ball and switch the unit on. Which to be honest is pretty much a user issue, not the device!


I actually had real problems getting the unit to update, and then maintain a connection to my phone, but I found that plugging to Polar A370 into my Mac and performing an update over USB seemed to resolve the issues for me.


Once the Polar A370 is setup and installed properly, you can also get the unit to sync with your phone via a long press on the button on the bottom LEFT, which will bring up the syncing logo


Regarding personalisation, the Polar A370 is actually quite limited, there are a few clock faces for you to choose from, as in five, and most are very similar actually. Oddly you don’t access these in the settings, or the Polar Flow app, but by long pressing the screen when the main clock displayed, from there you can scroll through your options.


However, the horizontal clock faces that were one the Polar A360 have now been dropped. It’s vertical from here on down!

Polar A360 review

To actually start using the Polar A37, it normally wakes on a flick of the wrist, or by pressing the bottom LEFt button. With the unit active, all navigation is by swiping up and down through the app carousel. The order being, My Day>> Training>> My Heart Rate>> Setting


Tapping into My Day will display the activity tracking for far, and how far you are towards your goal. It basically gives an overview of your day

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Also, at the bottom of the overview, is the number of inactivity warning symbols you have “generated” through being sedentary during the day. However unlike most Garmin units, and the Apple watch, the Polar A370 doesn’t give you little inactivity nudges during the day.

The Polar A370 monitors your total step count using its internal accelerometer, and as it does so calculates your total daily distance and calorific burn.

Swiping down will allow you the data on the continuous heart rate monitoring from the A370.

Polar A370 24×7 Optical Heart Rate Monitor

On the next tab is an overview of your cardiac rates, including min values over both the night and your min over the day, which is a great way of giving to the more realistic idea of individuals resting pulse.


Also, your max HR is also displayed, which can be very interesting on a day where you did think, at least, you were doing anything particularly active!

For the 24×7 optical HR, the Polar A370 monitors your pulse every 5 minutes during your day to day life, but when doing an activity monitored from the band, the Polar A370 increases the frequency to check the rate every second. Well until the battery drops low, and then when you are alerted to the battery status the 24×7 monitoring is disabled

In spite of the gorgeous screen on the Polar A370, there is limited screen real estate, so it is best is you swap over the the Polar Flow app to see the graphical data. On the graph is highlighted your max and minium (both night and day) heart rates. In addition to tag showing when you were doing workouts


You can also view your day in the Polar Flow app using a clock face, which I find actually a very effective visualisation strategy



Once you have finished with your heart rate, going back to the Polar A370 My Daym if you swipe up from the first page on My Day, you get an overview of how you’ve slept, which is a good point to look at one of the headline features on the new A370

Polar A370 Sleep Tracking Features

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From this overview, you can tap on the tab to dive deeper into your results. You can get even more detail when the Polar A360 with your phone and access the Polar Flow app


Comparing to the Beddit sleep tracker the Polar A370 is genuinely surprisingly close regarding monitoring how long I slept


If we look at the detailed sleep stats from the Beddit, compared to that of the A370, it appears that the Polar A370 is slightly less forgiving than the Beddit when it comes to sleep quality. Or that I tend to flail my arms around more than my body when I’m sleeping!

Polar is very happy for you to know, and then potentially improve your sleep. As sleep is vital to sports performance. As a result about an hour after you have woken, your wrist gives you a quick buzz, to actually tell you how long you have been sleeping


Activities on the Polar A370

A sports band isn’t much good, without the…well sports. Going back to the main app carousel we have Training which allows you to select whichever activity you want to take part in.

Polar A360 review

You can add any of the vast range of activities on the Polar Flow website to the A370

Screen Shot 2017-08-22 at 22.11.36.jpg

Let’s stay with running for a moment. While there is no GPS in the unit, the unit takes your GPS location via Bluetooth from your phone.

Polar A360 review

But if you happen to run out of battery on your phone during a run, you will get a heads up that the phone is no longer connected, indicating a loss of GPS tracking


However the Polar A370 will continue to time, and monitor your heart rate during the rest of the activity until you’ve completed your run

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When you select any of the training modes, the heart rate monitor activates, and you get constant readouts about heart rate zones, calorific burn and overall activity duration. All of the information is rendered in beautiful colour. Beautiful colour it may be, but as you can sometimes see that gorgeous screen does make for the easiest reading. You get heart rate, time and calories directly, along with distance and speed taken from the GPS on your phone

The question at this point, is how accurate is the Polar A370 heart rate sensor when on the run? When you view the run on the Polar Flow app, you get a nice clear breakdown


But the real question is how accurate is the optical hrm? So the effort on the run was compared with the Polar H10 HRM, the 4iiii chest strap, Apple 2 and the Garmin Forerunner 35

Screen Shot 2017-08-19 at 17.22.48.jpg

For the first ten mins of the run, all three optical devices, the A370, forerunner and the Apple watch all over the place. Normally this can be attributed to the devices warming up, but I’d been wearing the A370 all day. However, once things have “warmed up”, we see much better tracking, but disregarding the first ten mins of a 5km jog when it comes to data recording isn’t that great.

Swapping over to a cycle ride instead, how did the optical HRM fair?


Again we see a slight blunting for want of a better word across the HR trace compared to the chest straps. However, the track is overall much better than during the run, which is unusual, as normally things get shaken to pieces on a bike ride. There are certainly two reasonable intensities here, but I wonder if the addition of the ShockStop Stem is reducing movement, and thus improving the output?

Screen Shot 2017-08-19 at 18.03.00.jpg

As a final piece of heart rate tracking is two-fold. You can scroll down through the app to My Heart rate at any time.



This will do as it suggests and display your instant heart rate


As with the Polar M430, you can broadcast the optical HR to another Bluetooth enabled device.

Which is done from the Settings menu at the bottom of the app carousel – which is also where you can switch off the 24×7 HRM if you wanted to save some battery life

Currently, the broadcast HR doesn’t work with Zwift, but this is an issue on the Polar side which will hopefully be addressed in future A370 firmware updates


But I haven’t had difficulty attaching the Polar A370 as a heart rate sensor to other devices or apps, such as the Wahoo Elment Bolt


Although the HR broadcast is either/or. In a sense, you are using the Polar A370 to track your workout, or broadcasting the HR. Not both as is possible on some Garmins.

Smart Notifications

The Smart notifications work in the same way as other Polar devices. You get a small vibration from the unit, and a single screen of info, and it’s for your eyes only – the notifications are that, merely notifications and one way only. You can’t dismiss a call from your phone, nor can you scroll to look at additional information that might be displayed. Which is a shame, as the screen is more than capable of displaying beautiful streams of information and wonderfully responsive, would it have been too difficult to let me scroll through the rest of the message?

At least the nice big cross makes it easy to dismiss from the Polar screen

Polar A360 review

If you long press the side button, it brings up the supplementary screen allowing you to switch Bluetooth off, go into plane mode, or do not disturb, if you’d prefer not to have messages coming through to your wrist



Polar A370 Conclusion


When the original Polar 360 came out, I think the unit needed a little more development time. This year’s update has certainly provided that. The improved accuracy, addition of strong sleep tracking, and heart rate broadcasting has made for a much stronger product.

So many points about the A370 are very minor, such as the min and max hr readings, the ease of the Polar app, and the huge range of activities. But actually they add up to give a very compelling product, which is still, in my opinion, one of the most stylish trackers on the market, and for many people that alone will be a key feature!



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