I’ve been using a Garmin Fenix 8 for over a year and generally trusted the wrist-based heart rate data during walks, workouts, and recovery tracking.
Today I did a side-by-side comparison that made me question how accurate my wrist HR has been for walking workouts.
I regularly do the same neighborhood walk that includes rolling hills.
Walk 1 (Fenix 8 wrist HR only):
- 3.97 miles
- 1:09:20
- 17:28 pace
- 420 ft elevation
- Avg HR: 110 bpm
- Max HR: 138 bpm
- Zone 3: only 10%
Walk 2 (same route, using Garmin chest strap):
- 4.33 miles
- 1:13:18
- 16:57 pace
- 400 ft elevation
- Avg HR: 122 bpm
- Max HR: 144 bpm
- Zone 3: 27%
What surprised me:
- The route was nearly identical
- I actually walked slightly farther today
- Pace was a little faster, but not dramatically different
- The wrist sensor appears to have underreported my average HR by 12 bpm
That feels like a pretty meaningful difference because it completely changes how Garmin categorized the workout.
With the wrist sensor, Garmin made it look like I was mostly doing very light Zone 1 work.
With the chest strap, it showed I was actually spending most of my time in Zone 2 with meaningful Zone 3 work.
Now I’m wondering how many of my workouts over the past year have been misclassified. My whole motivation for getting the chest strap is due to the watch showing a low HR when I’m sure I was near my max.
For those using a Fenix 8 (or other Garmin watches):
Have you noticed wrist HR being significantly off during walking, hiking, lifting, or interval workouts?
And for people who switched to a chest strap full-time was it worth it?