Device: Garmin Forerunner 965
Software version: 26.08
Issue: Incorrect wrist-based heart rate readings during running
Since updating to firmware 26.08, my Forerunner 965 has been consistently showing significantly higher heart rate values during running activities. The readings are usually 15–25 BPM above my real effort.
Example from today:
- Distance: 8.5 km
- Pace: ~6:00 min/km
- HR shown: 160–166 BPM for most of the run (this is unrealistically high for this pace)
- Terrain: downhill start, flat track, uphill finish
- The HR only seems realistic during the final uphill section; the rest of the run is clearly overestimated.
Before version 26.08, wrist HR was accurate and consistent.
Troubleshooting already tried:
- Restarted the watch
- Tightened the strap
- Cleaned the sensor
- Repeated runs with the same result
It looks like the optical HR algorithm is stuck at higher values and does not react properly to changes in intensity.
Please forward this to the development team. Is a fix planned in an upcoming firmware update?
