Garmin Forerunner 935: Product Review

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I bought my Garmin Forerunner 935 when I realized that the battery of my four-and-a-half-year-old Forerunner 620 was giving up the ghost.  Over Memorial Day weekend, it had taken me through the Patch Sprint and the post-race self-extrication, well over six hours.  Six months later, a 10 km ski race at Gore just about drained the battery.

The Garmin Forerunner 935 is a big step up from the Forerunner 620.  It took me a couple of weeks to realize I was fully immersed in wearable technology.  In addition to the de rigeur heart rate, distance, and elevation gain, it tracks sleep, stress levels, steps, calories burned, and more.  For example, I chose not to send notifications about text messages and phone calls to my Forerunner 935; I don’t want the distraction.

When setting up the device, you can load workout types – running, cycling, nordic skiing, indoor cycling, and many others.  This is a lot easier than the Forerunner 620, where you had to select the activity once your workout was finished and loaded to Garmin Connect.

Although the 935 uses wrist-based heart rate, I prefer to use a chest heart rate transmitter. The 935 recognized the external chest strap automatically.  With the old Forerunner 620, one had to pair the chest strap to the device before the first use.  With the 935, I’ve used both wrist-based heart rate and the chest strap during workouts.  During a hill-bounding workout, the wrist based heart rate lagged my perceived heart rate and may not recorded my actual high heart rate for the day.  The chest strap has consistently given a more accurate reading.  

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One of the screens available on the Garmin Forerunner 935

Manufacturers of wrist-based heart rate devices would have you believe that they’re just as accurate as chest straps, but articles in Trail Runner Magazine and on BikeRadar tell a different story. The American College of Cardiology feels the same way.  The bottom line seems to be that for casual use – hanging around the house, walking etc. – wrist-based heart rate is reasonably accurate, but has intensity increases, accuracy drops off.

PRO

What does the Garmin Forerunner 935 do well?  With a chest strap, it tracks heart rate accurately.

The Forerunner 935 uploads data immediately after I save the workout. The old Forerunner 620 was often challenged transferring data either via Bluetooth or Wifi.  With the clear instructions in the downloadable owner’s manual I was able to change displays to my preferences.

The battery life is great.  I’m charging this every eight days or so.

CON

For me, the 935’s primary weakness is the way it sets heart rate zones.  You plug in your maximum hear rate, and it has five heart rate zones.  Warmup starts at 50%  of max, and zone five is 90-100% of max.  However, its heart rate zones don’t correlate with those developed by the exercise physiologist that administered my last VO2 max test.

One of the workouts the Garmin Forerunner 935 tracks is strength.  You’re able to start and stop sets, and add exercises afterwards from a long dropdown list on the Garmin Connect app or the website.  Only problem is, the two times I tried it, the 935 didn’t track reps accurately.  In one strength session, it only tracked reps accurately in two out of 27 sets.  It’s far from a deal-breaker for me, and I appreciate Garmin’s effort to provide a complete range of workouts.  They just need to tweak it a little.

Conclusion

If you want more bells and whistles, such as playing music from the watch, or being able to make payments, Garmin has other options. But the Garmin Forerunner 935 is a comprehensive, straightforward tool for the endurance athlete.