Data Driven Running: Comparing the Apple Watch and Garmin Forerunner 935 Data
Growing up, I never considered myself an athlete. I never found enjoyment in playing sports. Instead, I preferred staying indoors and spending my freetime in front of a computer. In 2014, that all changed when I signed up for a half marathon and started to train. From the very beginning, I started to track my runs with apps like Nike Run Club and Strava. As smartwatches and connected devices grew in popularity, I began to collect those devices and use those tools to collect even more data on my workouts. Almost five years later, my two go-to devices to track my runs are the Garmin Forerunner 935 and the Apple Watch. Let’s take a look at how the two devices differ!
Simplicity vs. Complexity
Apple ecosystem is known for its simplicity and ease of use, and tracking your workouts and viewing your data from your workouts is simple and easy. For the casual runner, this simplicity is great. Want to know how many calories you burned, distance you ran, and your pacing? Well, that data is easily viewable and presented in an easy to digest fashion.
You get data points on:
- calories (active & total)
- distance
- elevation gain
- total time
- average cadence
- average heart rate
- average pace
- heart rate graphs
- mapping data
To me, this is one of the great features of the Apple watch, but also one of the weaker. Having this high level view is great and informative, but if I wanted to dive in and see more data on my run (for example correlating my heart rate with current pace), its pretty much impossible to do from within the Apple Ecosystem. You can import that data into Strava and use their tools to parse the data and display additional info, but I wanted to compare the watches from within their ecosystem.
Garmin on the other hand drops that simplicity and adds in some complexity to their devices and application which enables users to learn more about their performance.
While Garmin does offer some high level views (like the one in the top screenshot) that gives you a quick snapshot of your performance, the watch does capture more data points and their app presents more of that data to give you a better picture of your workout.
For a more serious runner, this data can be helpful tracking your overall performance. For example, when I’m doing my strides and trying to have sprints where I try to run my fastest and hardest, I can track the changes in my best pace and max speed to see if I’m actually running faster. In addition, I can view that data in a graph where I can see how long I sustain those speeds for and also correlate that performance with datapoints that can reveal my overall effort during the workout. All this data at the end helps me better understand me as a runner.
Mapping and Tracking
Both the Apple Watch and Garmin have built in GPS enabling the devices to track where you’ve ran. Interestingly, the two devices performed differently here resulting in slightly different maps. I suspect this may be due to one of two things:
- The different GPS signal strength per device. I had my Garmin set to GLONASS+GPS while im not sure what Apple does with their watches
- I think the Apple Watch primarily uses my phone’s GPS — if this is true, this can explain some of the discrepancies as the phone’s signal may vary depending on various factors
The screenshots here are from the same run. I wore both watches on the same arm and started them at the same time. If the two functioned the same, the mapping data should be the same and the results of the two races should be relatively close to each other. However they were a bit off by almost .2 of a mile in a 30 minute workout. I decided to take a look at the data and see where they two devices differ.
From a high level, the two maps do look the same. It was nice how the Apple Watch data correlated performance on the map using color coding, while the Garmin presented mile marker points during the run.
As we zoom in and compare parts of the map, we can start to see some of the discrepancies between the data the two devices collected.
Taking a close up look towards the start of the race, you can see that both watches were started at roughly the same place. However, if we see the ending points of each watch, they are quite different. I did stop both watches a the same time so I can’t explain why the map had different data.
Also, if you pay attention at the first right turn I made, the overall shape of both maps are the same however it does feel like the Apple Watch data has a bit less “resolution” and tracked my turns in that area too early possibly resulting in a reduction in overall distance that I actually ran.
In this second close up, it looks like the location data on the Apple Watch seems to quite off. I was running parallel to the freeway so based on that, the Garmin does have the more accurate data here. The Apple Watch thinks I curved into the park and ran back towards the freeway which I definitely did not do.
In addition, there was an area where I made a shart turn. From the looks of it, the Apple Watch undercut my run in that area too, where as the Garmin did a better job in capturing the turn.
In this last comparison, the Apple Watch missed another sharp turn. I had ran past some fences and made a sharp u-turn to make my way back on the dirt track. The Apple Watch seems to have missed that detail as well.
Overall, this is just one dataset to look at and not a conclusion of which device is better or worse. I did take both watches out for a second run together and their data had more parity with each other.
Personally, I have enjoyed both devices. I feel that the Apple Watch is good enough for the casual runner, but excels in tracking non-running workouts like HIIT sessions and strength workouts. On the other hand, the Garmin does excel at running (and probably other workouts that I dont do), I feel that it doesn’t perform well in some of the workouts which the Apple Watch did better in.