August 10, 2017


If you’re looking for a good all-around fitness tracker that gives you a good variety of features, then you’ve probably considered the Fitbit Charge 2.

Fitbit’s tracker has a good, diverse set of abilities, including mindfulness and sleep. Fitbit’s recent obsession with sleep is well known, and both its sleep insights and stages provide valuable information on your beauty rest. But now Polar is entering the wellbeing arena with the A370 and its new Sleep Plus technology.


In addition to that, Polar has also brought all-day heart rate monitoring to the A370, going right up against the Charge 2’s continuous heart rate tracking, and following in the footsteps of Gamin’s Vivosmart 3. Then again, Fitbit has features like guided breathing, VO2 Max and automatic workout tracking in its arsenal.

Is that enough to see off Polar? Or does the A370 have something better suited to your needs? Let’s find out.



In the design realm, neither the Charge 2 or the A370 are going to bring you much excitement. In fact, what swings this category might be which design turns you offthe least.

That’s especially true for the A370, which kind of looks like wrapping Laffy Taffy around your wrist. It’s not hideous, but it’s also not pleasing to the eye. However, you may have to opt for a duller color rather than a brighter one, like the orange band we tested.

Regardless of looks, we’ve found the A370 to be quite comfortable to wear. It’s chunky, but it’s not obtrusive. In terms of size it’s actually very similar to Fitbit’s counterpart. As for the Charge 2’s design, it certainly carries over Fitbit’s design ethos with a nice polished body that’ll fit in whether you’re at work or at the gym. Both let you swap out bands, but Fitbit has made more of a conscious push in this.


Where the Polar wins in the design department is the display. It’s a bright, vibrant display, which is much preferred over the Charge 2’s more simple, more monochromatic display. The A370 even uses that color to tell you information in neat ways, like a watch face with bold numbers that fills up with blue as you inch toward your daily goals.

Another area the Polar wins is for swimming. The A370 is waterproof up to 30m, while the Charge 2 is merely “splash proof”, which means you can use the A370 for swimming workouts. That said, Polar warns that the heart rate accuracy may be compromised by the water.

On looks alone, the Charge 2 wins here. With a better variety of bands and a slightly less glaring design, it does a better job of blending in. That said, the Polar definitely has a much better display (though at the price of battery life) and waterproof abilities that make it feel a tad more robust.



One of the A370’s biggest leg-up over its predecessor is all-day heart rate monitoring. The tracker will monitor your heart rate every five minutes when you’re not exercising and every second when you are. The Charge 2, on the other hand, offers continuous heart rate monitoring no matter what you’re doing.

The A370 experience is a little more bare than that on the Charge 2. You can check your heart rate, launch a workout, dive into the settings and, well, that’s pretty much it. There are quite a few workouts to check out, and you can build your own in the Polar Flow companion app and sync them over. Most of them, however, are just changing up the heart rate zones and using GPS.

Speaking of GPS, both devices use connected GPS, leaning on your smartphone to provide the smarts. In our tests, we found the A370 kept buzzing to tell us it had lost GPS connectivity. Annoying.

As for the Charge 2, it’s about as fully featured as you can expect. You’ve got your heart rate tracking and step tracking, but you’ve also got automatic workouts, guided breathing and VO2 Max.

If you want a bevy of different features, the Charge 2 is the best choice here. The variety it offers is convenient, despite the lack of swimming ability. However, if you want something for focusing those runs or bike rides, with an accurate HR monitor for 24×7 tracking, the Polar will suit your needs just fine.



If you’re looking for more in-depth or extreme fitness tracking, neither the Charge 2 or the A370 are going to satisfy your demands. Both devices do fine on the lower settings, but when you turn up the intensity they tend to stumble.

We found that the Charge 2 was more miss than hit when it came to HIIT training. When compared to a Garmin Fenix 3, for example, it lagged an interval behind. The Garmin would have 180bpm while the Charge 2 would still have 115. It also lagged in locking onto our heart rate when compared to a chest-based tracker.

The A370 – for the most part – did a better job of keeping up with the chest strap than its predecessor, the A360. While on one run we had a problem where sweat appeared to be obfuscating the sensor, on others it managed to keep close on highs and averages. It wasn’t perfect on zones, struggling to stay in the highest bracket at times, but it performed fairly well, certainly better than we’ve seen on a lot of other trackers out there.

The big new thing on the Polar though is sleep tracking, with technology that the company is calling Sleep Plus. It breaks your night down into ‘Actual sleep’ and ‘Interruptions’. And, well, that’s pretty much it. It’s a shame there’s not more variation in the analysis, especially when compared to the Charge 2’s offerings.

The Charge 2 uses a combination of accelerometer and heart rate to determine when you’re awake, in deep sleep, REM sleep and light sleep. It can then give you insights on your sleep and the sleep of other Fitbit users every morning. It’s more useful than Polar’s offering and, frankly, makes Polar’s new sleep tracking data feel already antiquated. One of the reasons the A370 doesn’t deliver as much data is that, while it registers heart rate during sleep, it doesn’t harness it to separate your different levels. It’s only using the accelerometer. It’s not bad, but it’s not as good as the Charge 2.

On the whole, it depends on what kind of activity you’re looking to track. We’ve found the Charge 2 a little more mixed in heart rate performance than the Polar, but both are similar in other respects. That said, the Charge 2 is still a better all-rounder, and if sleep tracking is important to you, you’re not going to find a better wrist-mounted option right now.



One of the A370’s best strengths – that display – is one of the reasons its battery life doesn’t measure up to the Charge 2. The A370 doesn’t get bad battery life, it hovered around five days for us, but that color display sucks juice much more than the Charge 2’s monochromatic display, and it shows.

On the other hand, we’ve gotten a very solid week with the Fitbit Charge 2. And that’s with notifications, sleep tracking, continuous heart rate and more working all day, every day. Even better, it only takes about 15 to 20 minutes of charging to get another week of battery life.


On the price front, the Charge 2 is the winner. It goes for $149.95 while the A370 is a more expensive $179.99. The Charge 2, of course, comes with a variety of bands that range from $29.95 to $69.95.



The Fitbit Charge 2 and Polar A370 are very similar in a lot of ways, but it still comes down to what you’re really looking to track. Both are meant to be worn all day, but Fitbit’s is better equipped for overall wellbeing with guided breathing and, perhaps more essentially, better sleep smarts.

If you’re a swimmer then the A370 is your obvious choice, as it’s the only one that’s fully waterproof. If you’re big on running, we’ve also found the A370’s optical sensors a bit more accurate. But the other big consideration is price. The Charge 2 does more for less, as it has a larger variety of features for a cheaper price.

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