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Polar Grit X review: A superb sports watch

Our Rating :
$308.68 from
£299.99 from
Price when reviewed : £390
inc VAT

The Polar Grit X delivers great sports tracking and analysis but just falls short on polish and features


  • Light and comfortable to wear
  • Superb sleep tracking
  • Easy to use


  • Routing is basic
  • Touchscreen is sluggish
  • Unreliable sync

On first impressions it would be easy to dismiss the Polar Grit X. Its display is dull, its touchscreen is sluggish and it looks – well, nondescript would be the kindest way of putting it.

But this is a sports watch with hidden depths and it’s only once you start using it for the purposes for which it is intended – running, cycling and working out in general – that you realise it’s a serious contender in the sports wearables game. This is a watch that deserves to be considered as a serious rival to the market-leaders.

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Polar Grit X review: What you need to know

The Grit X is the tougher, rougher (MIL-spec tested) version of the Polar Vantage V and Polar Vantage M we looked at last year and it adds a number of new features intended to benefit those whose interests lie in outdoors activities.

There’s now route planning and turn-by-turn route guidance plus support for Strava Segments. Automatic “Hill Splits” make it easier to track your performance when you’re going uphill or downhill. And a food and water intake alert system ensures you keep your body fueled at the right time during workouts longer than 90 minutes.

These go hand in hand with features you may be familiar with from Polar’s Vantage range of wearables. These include continuous heart-rate tracking, GPS support, plus a compass and barometric altimeter, which the watch uses for its hill split feature. There’s long battery life, too, with the Polar Grit X offering up to 40 hours of full GPS and heart rate usage per charge.

The only feature the Grit X lacks compared with the pricier Polar Vantage V, in fact, is Recovery Pro, a recovery advice feature that lets you know how long you should rest before working out again.

Polar Grit X review: Price and competition

The Polar Grit X is a premium sports watch and costs £390. In this price bracket, there’s plenty of tough competition, notably from market leader, Garmin.

The Garmin Fenix 6 Pro, although more expensive, offers stacks more features, including music playback support and onboard maps, plus a host of serious training tools and awesome battery life. It is, however, nearly £200 more expensive than the Polar Grit X.

Closer in price and features to the Grit X and our choice at this price is the Garmin Forerunner 945, which goes for around £500 and is our favourite serious sports tracking watch. It comes with many of the features the Fenix 6 Pro includes but in a lighter, cheaper package. And if you don’t want to spend this much, the Garmin Forerunner 245 Music is another killer sports watch from Garmin. It comes with music storage, too, and has most of the features any runner would want for a mere £270.

Polar Grit X review: Design

The Polar Grit X isn’t much to look at. Its reflective colour LCD display is dull compared with the best smartwatch displays and the watch case itself is fairly plain. It has a plastic body topped with a stainless steel bezel and is available in three colourways: all black, silver with a green strap and silver with a white strap.

What the Grit X lacks in aesthetics, however, it more than makes up for in terms of practicality. The watch is sturdy and lightweight and doesn’t stand so proud of the wrist that it’s difficult to tuck under shirt cuffs. It’s also pretty comfortable to wear for long periods, which is crucial because Polar’s continuous heart rate monitoring and superb sleep tracking means it’s designed to be worn all the time.

And although the touchscreen doesn’t work all that well – it felt laggy and slow to respond just like the polar Vantage V – the Grit X’s five large circular buttons (two on the left, three on the right) work brilliantly for navigating the various features and functions, especially while exercising.

Combine this with water resistance down to 100 metres and excellent screen readability in outdoor light, and you have a watch that’s as well-suited to sports tracking as any other on the market. It’s a sensibly designed watch – not fussy or flashy but it does the job admirably well.

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Polar Grit X review: Sports tracking and new features

As you’d expect of a high-end sports watch, the Polar Grit X is brimming with sports tracking and analysis features and, for the most part, these mirror those found on the Vantage V. This includes Polar’s innovative Running Power feature, which aims to provide a live estimation of the amount of work you’re putting into a run, so you can train consistently, even when you’re toiling up hills.

You also get comprehensive sleep tracking and this is among the best I’ve seen on any fitness wearable. Not only does the Grit X track the various sleep stages – light, deep, REM and interruptions – but it also uses the heart rate monitor to track heart rate variability and your average breathing rate during sleep. The idea is to provide advice on how well you’ve recovered from your training exertions overnight and whether today is a good day to train, take it easy or take a complete rest.

This feeds into Polar’s FitSpark training system, which automatically recommends daily workouts across three main categories (Supportive, Cardio and Strength) depending on your recovery levels, general fitness and training history. These are detailed on the watch, complete with stickman animations in some instances – with supporting video content on the Polar Flow website. The idea is that, by following Polar’s recommendations, you avoid overtraining and potentially injuring yourself while balancing your training load so you improve your overall fitness level.

As you’d expect, there’s plenty on the sports tracking front here, too, and for most types of activity, from regular road running and treadmill pounding, to cycling. There’s also pretty comprehensive swim tracking built-in, with not only lap counting and stroke detection for indoor swimming (it will recognise freestyle, backstroke, breaststroke and butterfly), but also outdoor swimming tracking. It’ll even track your heart rate while you’re in the water, a feature many rival wearables don’t offer.

It’s the endurance and trail-based type of activity, however, that the Grit X is targeted at, especially with its set of new features.

The first of the new features is the on-device routing, which supports turn-by-turn features and route planning. This is an area in which Polar has been lagging behind rival Garmin for some time, so it’s good to see some improvements; it looks, however, as if it still has some way to go to match Garmin’s on-watch mapping.

First up, creating and transferring a route is fiddly. You first plan your route using the (non-Polar) Komoot app, which synchronises your routes with the Polar Flow app. Then, when the watch synchronises with your phone, the route is transferred for use. It’s a bit of a faff, made worse by the Grit X’s unreliable sync system (which I’ll discuss in more detail later).

The execution of route guidance on the watch isn’t all that impressive, either. It’s essentially breadcrumb trail navigation with added prompts at turning points with a wiggly line drawn on screen and sat-nav style “turn left” or “turn right” instructions issued every now and then. It’s a long way from the full-colour maps you get on a top-end Garmin.

And if that wasn’t bad enough, the Komoot app you need to use for planning these routes is only free for the first area you download. You have to pay for any areas you subsequently travel to. It’s not expensive, at £2.99 for single regions (e.g. Grenoble), £7.99 for region bundles (e.g. Isѐre) or £30 for the whole world, but a little galling when you’ve already spent so much on the watch in the first place.

One positive of the routing feature, although only for Strava Premium subscribers, is that you can also preload any favourite Strava Segments along your route. The Grit X will then alert you to these as you approach them.

The Grit X’s other new features are more successful. The Hill Split function uses the watch’s built-in barometric altimeter to automatically detect and deliver stats on the uphill and downhill sections, both while you’re running/riding and afterwards in the Polar Flow app. It isn’t as advanced as Garmin’s Pace Pro feature, which takes into account uploaded course data to give you advice on upcoming undulations, but it’s a useful extra metric nonetheless.

Polar’s Fueling feature is the last of the major new features and probably the best of the lot. It’s used for rides and runs longer than 90 minutes where you may need to top up on food and drink along the way. To set this up you enter the duration of the event and an estimate of its intensity (by heart rate zone), then add the amount of carbs (in grams) contained in each serving of your chosen gel. Once you’ve done this, the Grit X will remind you exactly when you need to top up. If your run or ride turns out to be more or less intense than your initial estimate (based on live heart rate data) the watch automatically adjusts these feeding times so you don’t run out of juice at the crucial moment.

In addition to this, you can also set up manual feeding alerts and drink alerts, to remind you to take on water and food at preset intervals.

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Polar Grit X review: Performance

So how well does this all come together? In most ways, very well. I’ve found the optical heart rate reader as good as any wrist-borne monitor I’ve used. Using a combination of red, orange and green LEDs, it has matched the heart rate reported from the MyZone MZ-3 belt I’ve been using as a reference to within a beat or two, and it reports very similar average, maximum and minimum values for each run as well.

And GPS accuracy was very good, too. You can choose between a combination of GPS and Glonass or GPS and Galileo systems and there’s Assisted GPS, too, to help you get a quick positional lock. Overall, I’ve had no major issues.

Moreover, in the past month I’ve found the Grit X a fantastically easy to use and reliable exercise companion. The screen that looks so insipid indoors is crisp and readable in daylight and, although the touchscreen is laggy, the large, clicky buttons – which give a light dig of haptic feedback when you press them – make navigating the UI so easy I barely noticed.

The Zone Lock feature, also found on the Vantage V and M, I’ve found particularly useful. This allows you to manually set a heart rate or power zone to ‘lock in’ as you exercise, and the watch will then alert you when you stray outside that zone. And I’m a big fan of the Polar Flow app and web portal, which present your stats and training data in a clear, clean and more modern fashion than Garmin’s rather ugly Connect UI.

Finally, battery life is good, although not quite as stellar as the 40 hour GPS usage figure might suggest. I’ve found the Polar Grit X tends to last four to five days between charges with moderate GPS usage (around three to four hours) and continuous heart rate monitoring enabled.

Alas, there are elements of Polar Grit X that don’t quite cut the mustard. I found synchronisation with my iPhone, for instance, to be extremely patchy and frustratingly unreliable. The watch is supposed to automatically sync every hour to keep battery demands to a minimum but it frequently failed to do even this. You can manually kick off a sync, which is simple enough, but I frequently had to toggle Bluetooth on and off or restart the app to get it to work.

And although I found GPS to be on the money when it comes to distance and accuracy, the way it behaves when you lose signal is slightly bizarre. Instead of guessing your position based on your previous speed, whenever it loses signal it holds your position at that point, then jumps ahead when it gets a lock again.

The result is that, if you go through a tunnel during the course of your run or ride or under a wide bridge, your pace drops off dramatically, only picking up again when you re-emerge. That’s annoying if you’re running strictly to a certain pace or power zone and it can easily knock you out of your stride if you don’t realise what’s going on.

Polar Grit X review: Verdict

It’s these small annoyances – and the rather basic nature of the new routing feature – that makes it difficult to recommend the Polar Grit X over its main rivals.

That’s not to say you should dismiss the Polar Grit X out of hand. It’s a superbly easy to use sports watch and has some unique features, such as running power estimation and automatic food intake alerts.

Plus, Polar Flow offers a ton of analysis and is presented in a much clearer, more attractive way than Garmin Connect, in my opinion. At the price, the Polar Grit X is definitely worth a look. It’s an excellent all-rounder.

However, Polar still has some way to go to catch up with Garmin whose sports watches remain the gold standard at around this price: namely, the Forerunner 945, which delivers more features and advanced tools; and the Forerunner 245, which offers most of the features a runner needs in a package costing £100 less.

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