Polar A370: Essential guide to the heart rate monitoring fitness tracker

Polar has officially unveiled the A370, the fitness tracker sequel to the Polar A360 that aims to right the wrongs of its predecessor and throws some new features into the mix as well.

Set to rival the likes of the Fitbit Charge 2 and Garmin Vivosmart 3, Polar's latest effort is going big on sleep monitoring and will still measure heart rate continuously throughout the day and night to better assess your fitness levels.

The verdict: Polar A370 review

If you want to know what to expect from the Polar A370, read on for our breakdown of the key features, pricing and when you can get your hands on it.

Polar A370: Design

The wrist-worn wearable looks a lot like its predecessor with its interchangeable silicone wristband that's available in small, medium and large and a similar slim glass colour touchscreen display. It's waterproof as well, so you can take it for a swim and at 13.5mm thick, it's as bulky as Fitbit and Garmin's flagship fitness trackers.

That capacitive touchscreen display manages to squeeze in a not so impressive sounding 80 x 60 pixel screen resolution, but if it's anything like the A360's screen it'll be suitable for glancing down at to review your stats.

Behind the display lies Polar's own optical heart rate module, which operates like most other light-based sensors. We weren't blown away by the heart rate tracking powers of the A360, but Polar does say it has improved performance particularly for high intensity activities. So now when more vigorous activity like running or walking is recognised by increased movement of the wrists, the '3D accelerometer' will measure heart rate at a higher resolution. The idea is that this should hopefully lead to improved accuracy.

Polar A370: Activity tracking

It packs in all of the same tracking features as the A360 so that includes counting steps, measuring distance and recording active time. It also offers inactivity alerts to keep you moving during the day and a useful Activity Goal option showing you how you can hit your daily fitness target.

In terms of heart rate based features, there's 24/7 heart rate monitoring taking resting heart rate readings at five minute intervals. There's also support for dedicated heart rate based training, the ability to view HR max information and a heart rate based fitness test. The latter does require having a compatible Polar chest strap though.

The big new addition is Polar's Sleep Plus intelligent sleep system that still harnesses accelerometer based tech to detect sleep duration, timing and quality of sleep based on position and wrist movements. The algorithm element of the system however uses polysomnography, a reference measurement, which is the test used to assess sleep in science and medicine.

The hope is that Sleep Plus can help provide much more accurate sleep detection. Users will be given a sleep continuity score on a scale of 1-5 to show how continuous their sleep was. You'll also be able to rate your night's sleep the following morning.

Polar A370: Dealing with data

When you need to review you data for the day you'll need to download the Polar Flow app (iOS and Android) or you can go old school and sync to a PC or a Mac. There's decent third party app support here as well letting you share data with Apple HealthKit, Google Fit, MyFitnessPal and MapMyFitness.

Data captured is synced to the Polar Flow app and combined with activity data and heart rate data aim to provide a more complete picture of your overall state of fitness. It will also provide further insights through Polar's Smart Coaching to offer advice on how to improve sleep and overall fitness.

Polar A370: Other features

One of the A370's nicest features is the ability to use the A370 as an external heart rate monitor for third party apps and other Bluetooth devices. You can also pair it with Polar's Balance smart scale and it'll work with Polar's H10 heart rate chest strap if you're yearning for more reliable HR accuracy.

You can still piggyback off your phone's GPS to track runs and it also offers indoor run tracking using the onboard accelerometer to measure distance, a feature that also rolled out to Polar's upcoming M430 sports watch. There's smartphone notification support too giving you a buzz when someone is trying to get in touch.

Polar A370: Battery life

The A370 receives a very minor battery upgrade moving from a 100mAh to a 110mAh battery, which should be good for up to 3 days of activity tracking. That also factors in 1 hour of training per day taking advantage of the continuous heart rate monitoring.

We found that the A360 could manage around five days, so it sounds like a conservative estimate in terms of how long the A370 can stay powered up before you're reaching for that micro USB charging cable. At least there's no proprietary cradle that you have to keep close by when it does power down.

Polar A370: Price and release date

The Polar A370 is going on sale in June and is available to pre-order now from the Polar website for . That's around the same price as the A360 when it first launched and puts it firmly in Fitbit Charge 2 and Garmin Vivosmart 3 pricing territory. If you want to buy some additional bands, those will cost you an extra per band.

The bigger push on sleep tracking is an interesting move from Polar, particularly when Fitbit has also made moves recently to improve the way its trackers record your bed time. What we really want to know is if those heart rate sensor problems have been resolved. There's clearly plenty of room for improvement and we're hoping that the A370 is a fitness tracker that delivers the goods this time.