We ran a marathon with the Apple Watch Series 5 – but was it up to the challenge

Is the Apple Watch good enough for running a marathon? That was the simple question I wanted to answer when running the Loch Ness Marathon.

Serious runners love their GPS running watch, but until recently that meant forking out for something like a Forerunner 245 Music or Polar Ignite. But the Apple Watch is now a seriously powerful fitness device, with an excellent heart rate monitor and bags of features aimed at runners.

We've had the Apple Watch Series 5 to live with for a few weeks now and already done our fair bit of running with it. But this test would take things up a notch.

I get asked a lot by keen runners weighing up whether to go for the Apple Watch or a dedicated Garmin sports watch, Polar or Suunto. Now's the time to really put that to the test.

So with the medal and the sore legs to prove it, here's what happened when the Apple Watch Series 5 got the marathon treatment.

The setup

So before we get into all things race related, I'm going to explain how exactly how this test was going to work and the kind of things I'd be looking for.

I'd be using an Apple Watch Series 5 GPS/LTE model on my right wrist and a Garmin Forerunner 945 on my left, connected to a heart rate strap. I was keen to see how the Series 5's optical heart rate sensor fared against a chest strap over such a long distance.

I would be focusing on the accuracy of the GPS tracking and the reliability of those core running metrics. Would it match the distance markers on the course? Did it accurately record the pacing of the run and aspects like splits and elevation?

And of course, the experience of using an Apple Watch as a running watch – setting up for race time, customising screens, the ease of glancing at your data during a run and of course, battery life.

While the Apple Watch does offer support for a whole bunch of third party run tracking apps, I chose to use Apple's own Workout app to track the runs and its Activity app to review data post run. I didn't stream music from the Watch or make use of the cellular connectivity.

There was a lot to explore and as anyone that has run a marathon knows, getting prepped happens a few days before race day.

Before the big day

While I'd put in serious running time with previous Apple Watches, I wanted to get fully acquainted with the latest one before race day, so I took it for a few runs ahead of time.

One of the neat things the Apple Watch does is fill in the gaps when GPS gets patchy – as it often does, especially around tree cover. And while the Apple Watch app has plenty of data about my running, I made sure to get a couple of steady runs in before the big day so it could learn my gait.

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I was using the Workout app to track runs, which in outdoor run mode displays as many or as few metrics as you want. If you're running with music, you can swipe right to view your controls and it's a swipe left to end the workout.

I still find it annoying that you can't press the Digital Crown or the Action button to end a workout, especially when you're scrambling over a finish line. It's the easiest and quickest way to do it and it's a shame Apple doesn't support it right now with its native Workout app.

Heading into the Workout app settings inside of the Watch iPhone companion app and there's a decent array of things you can play with, including the type of metrics you can display and whether the screen displays single or multiple metrics during a run. I decided to go with duration, heart rate, rolling pace, average pace and distance.

There are some other settings to highlight here as well. You can choose to turn on running auto pause (I didn't), and more interestingly, a power saving mode. In this power saving mode, you will disable the always-on display, mobile data, and heart rate monitoring during workouts.

Now before I get more into battery life performance later, I should state that I didn't turn this mode on and here's why: I wanted to track heart rate for this race. Like many people, I wanted the heart rate data on my wrist, so I could check I wasn't pushing too hard – particularly in the early stages.

So it meant that always-on display stayed on, but for race day I decided to minimise other factors that would impact on the battery life. I chose to have display brightness set to considerably less than half way, my iPhone wasn't connected during the race and no other apps were running. LTE connectivity was not set up either, to further strip back that Watch experience.

On the start line. It's race time

After a long bus ride up into the Highlands, I'm stood with thousands of other runners in freezing cold temperatures with a bin bag and an old hoodie over my race kit.

As far as the Apple Watch is concerned, there's nothing I really need to do apart from wait until it's time to start. The Apple Watch locks onto GPS automatically, unlike most running watches, so there really is no stress on the start line. Tap on the workout app, tap Outdoor Run, wait for the three-second countdown and it's time to get those feet moving.

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The first thing I notice on glancing down at the Series 5 is that it still has one of the best screens in smartwatches. It's super sharp, easy to read and overall just a lovely display to look down at.

In race scenarios, I'm generally most concerned about time, distance, heart rate and pace. But I was also interested in having the rolling mile data on the Series 5 that lets you see your split for the proceeding mile. It was a nice way to see if you'd sped up or dropped off and actually helped ensure I was keeping my pace more consistent.

The next thing to notice is the satisfying vibrating buzz you get when you've eaten up another kilometre of the course. It's not doing anything groundbreaking from a running watch perspective, but the combination of the little vibration and audible ding just does the job of making you aware of your progress.

Crucially, distance accuracy was totally in line with the distance markers on the course – so there were no complaints about accuracy.

From a comfort point of view, there's also no cause for concern here. Using one of Apple's sport bands, it didn't at any time feel uncomfortable to run with nor was there ever a reason to play around with or move it. Apple own's bands are clearly well made and I've made no secret that of the smartwatch makers who do make their own bands, Apple's are up there with the best.

Houston, we have a battery problem

Aside from checking in how I was doing at different stages of the race, there wasn't many other reasons for me to interact with the Watch. I wasn't listening to music while my iPhone remained in my bag many miles away at the finish line. But late in the race there did come another reason for me to raise my wrist.

Going back to the morning, I had charged the Watch overnight to ensure I had 100% of battery to play with for the day. It was an early start getting up at 5.30am and I put the Apple Watch on at around 6am. By the time I had got to the start line at around 9am however, the battery had dropped down to 65%.

As explained earlier, I had set up my Watch to minimise potential battery issues. Even with the always-on display mode, I made pretty minimal interactions with the Apple Watch in the morning. I probably went as far as to check the time, but that was really about it.

At about the 38km point a message flashed up on the screen to say that the battery was running low and was prompted to turn on Apple's power saving mode. In doing that, I'd be disabling the run tracking. With 4km to go, I decided to risk it to see if it would make it and dismissed the notification to see if it could get me to the finish line. It died with around 10 minutes of my race left. For a comparison, my Forerunner took about a 20% dent in a battery life tracking the entire race.

Apple states that tracking an outdoor workout with GPS is around 6 hours. If you're using LTE/4G, then that drops down to 5 hours. It bases that GPS battery performance on testing done when not connected to an iPhone.

It was for that reason that I decided not to run with my iPhone as well. I did opt against putting it into that power saving mode that would've disabled the always-on display and the heart rate monitor. But those were features I wanted to have access to and I imagine other runners would want access to them too.

The GPS battery drain seems in line with Apple's quoted figure – but I didn't account for such a dent before starting the race.

Had I managed the watch to be 90-100% from the start line, I'm confident that the entirety of my 3 hour and 44 minute race time would've been recorded.

With the power of hindsight, I should have brought an Apple Watch portable charger with me to make sure the Apple Watch was topped up.

Race done, time for the data

It's only once I've managed to shower up and get it on its charger that I can review what data it did manage to record.

The quickest way to find that out from the Watch itself is by selecting the Apple Activity app. Of the 42km race the Series 5 had managed to capture 41.24km of it.

Mapping compared: Apple Watch Series 5 (left) and Garmin (centre and right)

As the screenshots above show, the mapping on both watches was identical. While the Apple Watch didn't track the entire race, the GPS tracking was spot on up to that point.

When it was time to dig into those running metrics, I wanted to see what it recorded in the way of lap/split times, which you can see below. Scrolling through those numbers, while there's a 4-5 second difference in those times, everything is well within the margin for error.

Split times compared: Apple Watch Series 5 (left and centre) and Garmin (right)

Average pace

Apple Watch Series 5: 5.13 min/km

Garmin Forerunner 945: 5:19 min/km

Average cadence

Apple Watch Series 5: 178spm

Garmin Forerunner 945: 180spm

Elevation gain

Apple Watch Series 5: 266m

Garmin Forerunner 945: 262m

Elevation max/min

Apple Watch Series 5: 305m (max)/-1m (min)

Garmin Forerunner 945: 279.6m (max)/26m (min)

Again, that average pace reflects what we found for the individual splits in terms of the difference from what the Garmin and the Apple Watch recorded.

It's the same with the average cadence data and elevation gain. The minimum elevation data though seems a little off on the Apple Watch and it's not really obvious why it would post a minus reading here.

Heart rate performance

By keeping heart rate monitoring turned on, it clearly had an impact on battery life performance, but it did give us an insight into how that HR sensor setup performed on a tough, unforgiving course with big hills throughout the course.

Essential guide: Using heart rate on the Apple Watch

As a reminder, I had the Garmin watch paired to a Garmin chest strap, a setup I've used to test the heart rate monitor performance of other watches. The Series 5 produced an average reading of 159BPM compared to the 158BPM the chest strap recorded.

The heart rate graph in the Activity app also suggests a similar 177BPM max heart rate reading to the chest strap.

Should you run a marathon with an Apple Watch Series 5?

My answer to that is yes. However, next time I would have to turn on that power saving mode - or think about turning the watch off until reaching the start line and getting the full five to six hours of data tracking.

Some runners may not want to sacrifice features like the always-on display mode, leave the phone behind, or take that hit of heart rate.

The Apple Watch Series 5 is certainly still a smartwatch that performs very well as a running watch, more so than other smartwatches. It's a lovely watch to wear, the screen is great and based on the data it recorded, it clearly does a good job of tracking those key running metrics.

Just be prepared to get that set up right before you get on that start line.