The Polar A370 isn't particularly flashy, but it's good at what it does.
It excels as a sports watch for training and tracking workouts, thanks in part to an accurate optical heart rate monitor.
It tells you how different activities affect your body, whether you complete an easy recovery run or a cardio-intense fitness class.
And sure, it offers all-day activity tracking and notifications from your phone for good measure.
Yes, there are better and sleeker all-day fitness trackers out there, but not at the A370's price point ($149.95).
If you're primarily looking for a sports watch to be your companion while training, it'll make you very happy.
Honest, Objective Reviews
Daxdi.com is a leading authority on technology, delivering Labs-based, independent reviews of the latest products and services.
Our expert industry analysis and practical solutions help you make better buying decisions and get more from technology.
Design, Comfort, and Battery Life
The Polar A370 is nearly identical in style to the device it replaces, the A360.
Both are waterproof and have a rectangular face with a micro USB slot on the back for charging (hooray for non-proprietary chargers!).
The A370 weighs the same, too, at 1.1 ounces for size S and 1.3 ounces for M/L. You can swap the same silicone bands ($24.95 each) onto either device, with Polar now offering new color options: ruby red in S only, and for M/L only, deep blue, orange, and petrol.
Those are in addition to the more classic black and ivory white.
One slight change to the A370 is a new strap closure.
It's a tricky little loop that you thread the loose end into, which, albeit an improvement over the prong closure from the A360, is a hassle because it's simultaneously tight and slippery.
It's not the most attractive fitness tracker, with a somewhat clunky look compared with the more elegant Fitbit Charge 3 ($149.95 at Fitbit) .
And its 160-by-80 pixel touch display isn't the sharpest, though it's perfectly serviceable.
The rectangular face takes some getting used to, as it felt clunky the first few days I wore it.
I still don't like wearing it to bed, which is a shame because the A370 uses Polar's new Sleep Plus analysis (more on that in a bit).
I do like that on the customizable face, you can choose a display that shows the time in a large white type that fills with color as you get closer to meeting your daily step goal.
The screen shows good responsiveness, and there's a single physical button on the outer edge, covered by silicone, for waking up the display, connecting to Bluetooth (press and hold), and backing out of menus.
Using the A370 is highly intuitive.
It takes little effort to figure out how to change the settings and navigate the screens without a manual.
On a full charge, the A370 can handle 12 hours of activity when using the GPS via a connected mobile device.
Otherwise, you can expect to get four days of battery life with normal use, which includes 24/7 heart rate monitoring and one hour per day of activity tracking.
That's markedly better than the battery life of the Apple Watch, which still doesn't even promise to last a full 24 hours.
Granted, the Apple Watch is a smartwatch, not a fitness tracker or sports watch.
In the latter category, however, Garmin remains the company to beat, with many of its best devices lasting nearly a week with typical use.
That's close to how long many Fitbit devices can go without recharging, too.
What Do You Want to Track?
The Polar A370 has plenty of activity tracking options, from everyday steps to weight lifting sessions.
With a few taps of the screen, you can record a run, walk, cycling activity, strength training session, and group exercise.
The A370 also has generic options for indoor and outdoor exercise.
I like that before you start, the watch shows two icons to indicate whether it has detected your heart rate and received a GPS signal from your phone (for outdoor activities only).
The A370 has all-day activity tracking as well, counting your steps, heart rate, calorie burn, distance traveled, active time, and how many long periods of inactivity you have in a day.
There's one big hitch with daily activity tracking: You can't set your own goals.
Polar creates them for you based on your lifestyle, history, and progress.
The benefit is that Polar creates goals that are achievable but not too easy.
The disadvantage is that you have little agency in setting your goals, aside from entering information about your lifestyle (which you can change at any time).
Most other fitness trackers allow you to set and adjust your goal however you want.
Undoubtedly, some people will feel frustrated by Polar's insistence on setting your goals, while others won't think twice about it.
Sleep tracking is included, too, using enhanced analysis from Polar's new Sleep Plus system, only available in the A370 and M430 ($139.99 at Amazon) .
You view your sleep data in the Polar Flow app (available on Android, iOS, and on the web).
The data and graphs provide insight into your night, showing not only bedtime and wake time, but also interruptions, total sleep time, and sleep continuity (a one to five score essentially rating the severity and frequency of sleep interruptions).
In your Polar Flow account, you can also rate your sleep to keep track of how you personally feel, which can be more important than what the numbers show.
Polar offers a few excellent features and options for fitness enthusiasts, such as training programs you can load onto the watch, feedback about activities, and a fitness test.
If you're into interval or circuit training, you can create quick-access programs on your watch with custom timers and goal settings for your workouts.
For example, you can create a workout goal based on time, distance, or calorie burn so that the watch alerts you when you've hit it.
Or you can create interval timers to guide your workouts.
Another advanced feature that I find useful across Polar trackers is a summary of what good a workout or a day's worth of activity does for you.
The Polar Flow app has reminded me that a day spent walking and not being sedentary helps extend my life expectancy, for example.
After a tough workout, the app might tell you that you've improved your sprint speed and the nervous system of your muscles.
A slow jog will probably turn up as having recovery training benefit.
Fitness buffs will also get excited about Polar's five-minute Fitness Test for measuring VO2max and your aerobic fitness level compared with other people similar to you.
You need the Polar H10 ($87.95 at Amazon) chest strap heart rate sensor to do the test, so factor in an extra $75 if it sounds appealing.
You can use the H10 in conjunction with the watch for other workouts, as the chest strap is a better device for recording heart rate during certain types of activity.
I took the Polar A370 outdoors for a few runs and walks, and I did a more controlled treadmill walk test to get a sense of its accuracy.
In all, the Polar A370 performs accurately.
When using my phone's connected GPS, my route and distance matched up with Google Maps fairly precisely.
For one of my runs, I turned off the phone's GPS, and the A370 recorded the distance as being about 0.3 miles longer than it was on Google Maps.
Heart rate readings were where I expected them to be for different activities.
For the treadmill test, I walked one mile while wearing the Wahoo Fitness Tickr X ($79.99 at Amazon) chest strap to record my heart rate.
Having previously done dozens of one-mile walks while counting my steps, I know my stride puts me right at the average of taking about 2,000 steps per mile.
The Polar A370 clocked me at 1,971 steps and 0.96 miles, which is well within the range of accuracy I hope to see.
The heart rate readings lined up to the Tickr X's output, too, giving even more credibility to the device's accuracy.
In real-time, the A370 heart rate readings kept pace with the Tickr X better than any other tracker I've recently tested, with almost no lag time and never straying more than about 2bpm.
Fit for Workouts and Training
The Polar A370 excels as an accurate sports watch with some lovely features for training and daily fitness tracking.
Is it beautiful? Not exactly.
Does it pack in a bunch of smartwatch features? Nope.
But for $149.95, it's a worthwhile device for fitness enthusiasts who want heart rate monitoring, on-watch training sessions, and don't mind pairing a phone when they need GPS.
Definitely consider it if you're in the market for a watch to use while training.
If you're looking something slightly less specialized, the Fitbit Charge 3 is our favorite entry point into the world of fitness tracking for more casual users.
The Bottom Line
The fairly priced Polar A370 isn't the most attractive fitness tracker, but it records training sessions and daily activities with aplomb.