When you're training for a marathon, an ordinary running watch might not be enough. As you rack up the miles, you'll need a watch that'll be up to the challenge.
On-board GPS is a key feature for any running watch, and if you're preparing for a marathon you'll appreciate a watch that doesn't just track where you've run, but provides turn-by-turn navigation as well. Unless you're following a very straight path, memorizing long routes can be tough, particularly when you're tired, so a watch that'll keep you on course is a great training partner.
Battery life is also extremely important – a watch for marathon training will need to keep going for hours at a time with GPS enabled. Playing or streaming music will help keep you occupied during long sessions, but will also put strain on the battery – you'll need to be confident that it can go the distance.
The ability to download training plans is also a great addition. Many of the best watches for marathon training allow you to get plans from TrainingPeaks, download routes from Komoot, or create your own. They may also help you plan your fuelling strategy, helping you time your intake of carbs and water to help you stay hydrated and avoid hitting the wall.
With all that in mind, here are our picks for the best watches for marathon training. All of theses watches are ANT+ compatible, so they can use used together with a chest strap heart rate monitor.
Garmin has updated lots of its higher-end watches with solar glass, and the top-end Fenix 6 Pro is no exception. Three hours of sunlight per day is enough to give the battery a real boost (we were particularly impressed by how it extended the life of the Garmin Instinct Solar). With a little sunshine the Fenix 6 Pro can keep going for up to 40 hours with GPS enabled, or up to 10 with both GPS and music. There are also customizable power modes so you can prioritize specific functions to extend battery life in a way that suits you.
As you'd expect from any Garmin watch, GPS is superb, as is elevation monitoring courtesy of the on-board altimeter. We tested the watch on a tough slog in the Alps, and the results lined up with our measured route to within a meter.
Unlike the regular Garmin Fenix 6 (which is still a superb watch for marathon training), the 6 Pro includes a feature called PacePro that helps you optimize your pacing on hilly routes so you don't tire yourself out when the going gets steep. You can also preload the Fenix 6 Pro with your favorite running tunes and podcasts to keep you entertained when you're putting in the miles and turn your training into 'me' time.
The downside, as you'd expect, is that the Fenix 6X Pro Solar is seriously expensive. If you're working towards your very first marathon rather than aiming for a new personal best then it's almost certainly overkill, so read on for some more affordable options that will be a better fit.
- Read our full Garmin Fenix 6 review
If the Garmin Fenix 6 is too expensive for your marathon training plan, the Polar Grit X is a great alternative. While it's not as powerful, the Grit X manages to pack a whole lot of features for distance runners into a small, lightweight package – and for half the price.
Polar is a company made its name in biometrics (specifically heart rate tracking) and this is where the Grit X really shines. Rest and recovery are huge parts of effective marathon training, and this watch offers some of the best insights around – not only monitoring sleep stages, but also tracking the effectiveness of your night's rest, and suggesting activities to help with active recovery.
Polar's FuelWise system calculates the best times for you to take water and carbs on board so you remain suitably hydrated and don't run the risk of bonking, which will be a useful aid if you're not used to putting together your own fuelling plan for marathon training sessions.
GPS proved accurate in our tests, and you can download routes through Komoot so you have a path to follow right on your wrist. There's no support for offline maps, so you won't want to stray off this course if you're unfamiliar with the area, but the watch's turn-by-turn navigation will keep you on track.
Battery life isn't as impressive as that of the Fenix 6 Pro Solar (not surprising considering the lack of solar charging), but up to 40 hours in GPS mode is impressive nonetheless, and is the most impressive of any Polar watch.
- Read our full Polar Grit X review
The Coros Apex Pro is another serious sports watch that's great for marathon training if your budget won't quite stretch to the Garmin Fenix 6 Pro.
The main difference between the original Coros Apex and the Apex Pro is battery life – the Pro can keep running for up to 40 hours with full GPS enabled, putting it on level pegging with most of the other watches in this roundup, and making it a better choice for long training sessions.
The watch harvests a wealth of stats during your runs, and we were particularly impressed by its cadence algorithm, which is extremely helpful if you're working towards increasing your cadence and limiting over-striding.
The app presents all your GPS and biometric data in a way that's clear and useful (if you're making the switch from a Garmin device, it's a similarly well designed experience), and it's compatible with both Strava and TrainingPeaks. There are various training plans available too, which is very handy for working some strength sessions in alongside your runs.
The Apex Pro's high-res color screen is excellent for mapping and navigation. Our only real criticism is that it could be brighter; it can be somewhat tricky to check your stats in bright direct sunlight. We do, however, like the way the digital dial can be used to zoom in and out; a nice feature that's easy to use while wearing gloves, or with sweaty hands.
- Read our full Coros Apex review
If you're preparing for your first marathon, the Garmin Instinct Solar is an excellent choice. Like the Fenix 6 Pro Solar, it uses Power Glass to keep its battery topped up between charges. With the right power-saving settings it could keep going indefinitely, but even with full GPS, a little sunshine will ensure you can keep training for 38 hours.
It has a new chipset and SpO2 monitor, but in terms of running tools it's very similar to the original Garmin Instinct. You can upload routes with point-to-point navigation (though the small screen means there's less detail than you'd get with higher-end watches), and Garmin's TracBack tool will lead you back to your starting point if you decide to embark on an out-and-back training session.
There's no music player so you'll need to rely on your phone, and you can't download additional apps through the Garmin Connect IQ store, but the Garmin Connect app gives you lots of options for exporting and managing your data. It also includes an adaptive marathon training plan, which adjusts its recommendations based on your fitness level and workout history.
Its price has dropped significantly since its release in July 2020, and you can sometimes snap it up particularly cheaply from third-party retailers like Amazon and Wiggle. A good investment, and built to last.
- Read our full Garmin Instinct Solar review
The Polar Vantage V2 is a small upgrade from the original Vantage V, but its new lighter aluminum case and improved music controls make it a much better choice for marathon training.
We found that results from its heart rate monitor were consistent with those from a standalone chest strap, and stats from your training sessions are all clearly presented in the Polar Flow app.
Like the Polar Grit X, the Vantage V2 offers excellent recovery insights through its Nightly Recharge feature, which shows how well you've recovered from the previous day's training session and helps you plan your next one to optimize its effectiveness. There are also performance tests available, so you can see the impact of your marathon training for yourself.
You can download routes through Komoot (though navigation itself is quite bare-bones), and there's support for Strava Live segments to keep you motivated. There's no music app, though – you'll have to play music and podcasts through your phone, though you can use the watch to control playback on the move without digging your phone out of your pocket or backpack.
We found the touchscreen a little laggy in our tests, but we always prefer using a watch's buttons while we're on the move, and these are tactile and responsive.
- Read our full Polar Vantage V2 review
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