If you’re a serious downhill skier, hiker, mountain biker, swimmer, or trail runner, you should definitely check out the latest addition to Polar’s multisport GPS watch lineup, the $429.95 Grit X. It offers everything the $279.95 Polar Vantage M does—including continuous heart rate tracking, overnight recovery measurements, and training guidance—plus outdoor-specific features like refueling advice for long training sessions and events, route planning, and uphill and downhill stats. It’s a niche product designed for serious outdoor athletes, but if you fall into that camp, this fitness tracker can really help you level up your training, earning our Editors’ Choice.
Design and Specs
The Polar Grit X comes in white in size small/medium (fits wrists measuring 5.1 to 7.4 inches), or black or green in medium/large (fits wrists measuring 5.7 to 8.4 inches). I tested the small/medium white model.
The watch feature an 1.2-inch color touch screen with a resolution of 240 by 240 pixels, plus five physical buttons. Together, the touch screen and physical buttons make it simple to navigate the interface.
On the right side of the Grit X, an OK button that lets you confirm selections sits between up and down arrow buttons that let you move through lists. On the left side, there’s a dedicated button that lights up the screen, above a back/menu/sync button.
The light button is helpful; when pressed, it illuminates the screen for a few seconds before turning off automatically. Indoors, the screen is pretty dim without the extra light on, but you can still read it. Outside, the screen is easy to read without the light.
The Grit X is rugged yet stylish. It’s waterproof to 328 feet, beating the Vantage M, which is rated to 98 feet, though both are safe to swim and shower in. It has a stainless steel bezel and case, a glass fiber reinforced polymer back cover, and a laminated Gorilla Glass lens with an anti-fingerprint coating.
Polar says the watch has passed several US military-grade tests ensuring it can withstand extreme temperatures, drops, and humidity, but warns that temperatures below 14 degrees Fahrenheit can affect battery life and performance.
The band is comfortable silicone, with a texture printed on the front that kind of makes it look like fabric. The bottom side of the strap that touches your arm is smooth. If you want to change the look, Polar offers compatible silicone, textile, and leather bands ranging from $29.95 to $49.95. The watch is also compatible with standard 22mm quick-release watch bands.
The small/medium model weighs around 2.2 ounces, which is a bit heavier than the 1.5-ounce Vantage M and the 1.7-ounce Coros Apex, though it still feels pretty light and comfortable on my wrist.
Overally, I like how the Grit X looks. It’s bulky, measuring 0.51 inches thick, but it has a nice classic watch design. The buttons on the side give it a sporty feel, but the watch face and bezel have a sophisticated look. I can’t see myself wearing it for a dressy occasion, even with a different band, but it looks good with athleisure and casual outfits, which is what I wear most of the time.
Polar says the Grit X can last up to 100 hours (just over four days) thanks to a suite of power-saving features. With the GPS running, you’ll get up to 40 hours of battery life. After my first 24 hours of testing, during which I tracked two roughly 25-minute runs with GPS plus a yoga session, the watch still had 79 percent battery life. All told, it lasted 110 hours before the battery got down to 9 percent and it said it needed to be recharged.
To access the Grit X’s power-saving settings, press the bottom left button, select Start Training, then press the light button. Here, you can change the GPS recording rate to every minute or two, instead of every second, or turn it off altogether. You can also disable heart rate monitoring and turn on a screensaver. These features are good for endurance events and long training sessions.
In comparison, the Coros Apex can last up to 24 days with normal use, 24 hours in full GPS mode, and 80 hours in a battery-saving mode called UltraMax, in which the GPS switches on for 30 seconds every two minutes (the rest of the time, it uses motion sensors and machine learning algorithms to track you).
To get started, just plug the Grit X into the included USB charger, which magnetically snaps into place. When the watch wakes, it will ask you to select your preferred language and whether you want to complete the setup process on your phone, computer, or the watch itself. If you opt to set it up via your phone, as I did, you’ll need to download and open the Polar Flow app (available for Android and iOS).
When you open the Flow app, it automatically recognizes the watch and prompts you to start pairing. Just accept the Bluetooth pairing request on your phone, then confirm the PIN code on the watch by pressing OK.
Navigating the Grit X
To access the main menu, tap the lower left button. From here, you can use the up and down keys or the touch screen to scroll through your options: Start Training, Settings, Fitness Test, Timers, Fueling, Strava Live Segments, and Serene.
I especially like the Serene feature, which guides you through a stress-relieving breathing exercise. By default, the exercise is three minutes with five-second inhales and exhales, but you can set it for two to 20 minutes, and change your inhale and exhale duration.
The Strava Live Segments feature lets you compete with other people for the best time running or cycling predefined sections of a road or trail. To use this feature, you need a Strava Summit Analysis pack ($5 per month after a 30-day free trial).
In Fueling, you get access to a feature called FuelWise that lets you set time-based reminders to eat and drink during long training sessions. You can also set a Smart Carbs Reminder that calculates the amount of carbohydrates you’ll need to refuel based on your estimated session duration and intensity, training background, and physical details like your age, gender, heart rate, height, and weight.
The Fitness Test is fantastic. The watch has you lay down and relax for about five minutes while it measures your heart rate. After that it tells you your VO2 Max, a measurement of the maximum amount of oxygen your body can use during intense exercise. The first time I tried taking the test, it failed because the watch was too loose. I tightened it and tried again. This time it worked and told me my VO2 Max was 50, or Elite.
In the Settings menu, you can enable and disable continuous heart rate tracking, do not disturb, flight mode, inactivity alerts, smartphone notifications, vibrations, and more. You can also swipe down from the watch screen to quickly access alarms, do not disturb, and flight mode, or swipe up to view your notifications. In testing, the Grit X did a good job alerting me when I had phone calls and displaying smartphone notifications from apps like Coinbase, Slack, and Spotify.
From the watch screen, you can press the up and down buttons to view your Cardio Load Status, current weather, FitSpark daily training guide, heart rate, Nightly Recharge sleep recovery measurement, latest training sessions, and progress toward your activity goal.
On each of the watch screens mentioned above, you can click the OK button on the right side of the Grit X for more details. In weather, for instance, you can see current humidity, rain totals, wind direction, and wind speed, plus a handy two-day forecast. Cardio Load Status tells you whether you are detraining, maintaining, productive, or overreaching, based on your previous training. FitSpark offers two to four different workout options each day, based on your fitness level, training history, and Nightly Recharge recovery stats. When you click into your latest training sessions, you can scroll through a list of your workouts to find the one you want to reference, then view all of your stats for it.
Training With the Grit X
The Grit X makes it easy to track your workout. Just press the menu button on the lower left, select Start Training, then scroll through the options and select the type of workout you’re going to do. There are options for body and mind, cycling, downhill skiing, hiking, mountain biking, multisport, other indoor, other outdoor, strength training, swimming, running, trail running, and walking.
To end a session, press the menu button again, then hold it down for three seconds, and the watch will automatically save your stats. If you mess up and start tracking a session when you didn’t mean to, then end it right away, the Grit X will ask if you still want to save your data, a nice feature that prevents you from having to deal with incorrect data or manually deleting it.
I first used the Grit X to track a 24-minute run/walk with my dog. My test unit was initially set to the metric system, but I discovered you can easily change the units to imperial in the Settings menu.
After a run, you can view a lot of metrics on the watch itself, including your altitude, average and best lap time, average and max heart rate, cadence, calories burned (and how much of that was carbs, protein, and fat), Cardio Load (the strain on your cardiovascular system), heart rate zones, Muscle Load (the strain on your musculoskeletal system), pace, Polar’s Running Power measurement, Power Zones, and Speed Zones.
Measured in watts, the Running Power metric helps you monitor how much you worked your muscles during a run. The company uses a proprietary algorithm to calculate this metric based on your altitude gradient and speed captured by the device’s barometric and GPS sensors, as well as your weight.
Like other wrist-worn wearables, the Grit X measures your heart rate optically, meaning it detects your blood flow through the skin on your wrist. To get the most accurate reading, the company recommends wearing it at least one finger’s width away from your wrist bone. You should tighten it so the device can’t move on your arm and the sensor on the back is touching your skin at all times.
Polar says you may want to pair your Grit X with a traditional chest strap heart rate monitor when playing racket sports that involve moving your hand around a lot, swimming, and training in the cold. When playing racket sports, you can also increase the accuracy of the Grit X’s heart rate measurements by moving the watch to your non-hitting hand.
After my first run, I was scrolling through the watch and happened upon the FitSpark training guide, which advised me to stretch out. I decided that was a good idea, and did a yoga session, which I also tracked on the Grit X under the Body and Mind category.
Route Planning, Hill Splitter
To help you prepare for an outdoor adventure, Polar has partnered with third-party mapping and route-planning provider Komoot to bring route guidance to the Grit X. Designed for bikepacking, hiking, mountain biking, and road cycling, the Komoot feature helps you find a suitable route according to your ability and available time. The watch then guides you through your selected route, offering turn-by-turn instructions.
Hill Splitter is another one of the Grit X’s differentiating features. It uses barometric altitude data as well as your GPS-based distance and speed to automatically detect uphill and downhill segments and report on your ascent and descent performance. By default, Hill Splitter is available when you track a cycling, downhill sport, or running session, but you can add it for any sport that uses GPS and barometric altitude via the Flow app or web service.
After starting a session, you can use the up and down buttons to scroll to Hill Splitter to view details of your ascent and descent. In downhill sports like skiing and snowboarding, you even get a pop-up with details about your performance after finishing a hill. After ending a session, the training summary will show the number of downhills and uphills you traversed and your distance.
Polar Flow App Features
The Polar Flow app is an excellent companion to the Grit X, offering even more useful insights that can assist your training. There are sections for Activity, Training, Nightly Recharge, and Sleep.
In the Activity section, you can view your stats for the day, week, or month. It shows your active time, calories burned, distance traveled, progress toward your daily goal, step count, and more. In this section, you can also see your highest and lowest heart rate of the day, and at which times they occurred.
In the Training section, Polar keeps a record of your workout history, and you can click into each session to view a detailed summary of your stats, graphs of your calories burned and heart rate throughout your workout, and a map of your route.
Training Load Pro aims to help you determine how often you should work out, based on how your training sessions have strained your body. It shows a value for Cardio Load, Muscle Load, and Perceived Load, which is based on your assessment of how difficult the workout was on a scale of one to 10.
For runs, you’ll see a Running Index score, a measurement of training efficiency based on your heart rate and oxygen uptake. Polar says that for women in my age range, a Running Index score between 38 and 42 is considered Good, a score between 43 and 46 is considered Very Good, and anything higher than 46 is considered Elite. For one 26-minute run on the beach, the app said my Running Index score was 38, or Good.
At night, the Grit X tracks your deep, light, and REM sleep, plus any interruptions. The app shows a graph of your sleep cycles so you can see how they fluctuated throughout the night, and exactly when and for how long you were in each stage of sleep.
It also gives you a daily sleep score from one to 100, based on how your shut eye compared with “indicators of a good night’s sleep according to current sleep science.” Polar says a typical sleep score is around 70 to 85. On my first night tracking my sleep I got a 72, and on my second night I got a 71.
After tracking your sleep for three nights, the Grit X fills in your Nightly Recharge status, showing how your body was able to recover from training and stress during the night based on information it collects about your sleep and autonomic nervous system. The watch and app first reported my Nightly Recharge Status on a Saturday morning, after I drank probably a bit too much red wine the night before. Interestingly, it said my status was Very Poor and advised me to “take it easy today by resting or training very lightly.” I took its advice and did a 30-minute yoga session.
The next night, my Nightly Recharge status was OK. It told me I was “good to go” for exercise, and advised me to check out the FitSpark feature for training guidance. On Monday morning, after a solid night sleep, my Nightly Recharge status was Good, meaning my autonomic nervous system was able to calm down more than usual while I slept. The app advised me to “go for it,” and said, “remember that if your body tells you to slow down, listen to it.”
Comparisons and Conclusions
Given its price, in-depth metrics, and outdoor features, the Grit X isn’t for the average person who wants to track casual runs and workout sessions. There are plenty of more affordable wearables that can help you track your exercise and monitor your health, like the excellent $149 Fitbit Charge 4, which also features GPS and a heart rate monitor, plus NFC for contactless payments and Spotify support.
The Grit X is meant for serious outdoor athletes, particularly those who train in the mountains. Its Hill Splitter, Komoot route planning, and FuelWise features make it a compelling option for anyone who likes to cycle, hike, mountain bike, participate in endurance events, run on trails, ski, or snowboard. The Grit X and its Polar Flow companion app will track your progress, motivate you to get moving, and offer insights to help you train more efficiently. Its long battery life, stylish yet rugged design, and useful outdoor-specific features earn it our Editors’ Choice.
That said, if you’re in the market for a triathlete-friendly multisport GPS watch and don’t need uphill and downhill stats, route planning, and refueling advice for long training sessions and events, the Polar Vantage M offers basically all the capabilities of the Grit X for $150 less. The Coros Apex is also a solid choice, offering excellent battery life and a data-rich companion app.
Polar Grit X Specs
|Display Type||Color Touch Screen|
|Heart Rate Monitor||Yes|
|Battery Life||4 days; 40 hours with GPS|