I replaced my Forerunner 55 with a Forerunner 165 two weeks ago and since changing watches my heart rate readings have been very high. For example, on an easy run last week, my heart rate suddenly increased from around 150 to over 200 and stayed that way for over 10 minutes (see image below). I was running at an easy pace downhill when my HR increased and I felt completely normal and could easily have held a conversation. On today's tempo run on the same route, I was working much harder and when I reached the same downhill section my heart rate jumped again, hitting a max of 230 bpm! I contacted Garmin support last week and they told me that the sensor on my old watch was inaccurate and that the higher readings on the 165 were correct. This seems insane - surely my HR can't reach 230 without me noticing anything?
I should add that I am a 51 year old female, running around 25-30 miles per week, usually slowly. Over the past 3 years with my old watch my max heart rate has hit higher numbers before, on a few occasions above 200, but only for a few seconds during very long hilly runs. My resting HR is usually around 45 and seems to be the same on the new watch as the old one.
Has anyone else experienced this issue? I'm wondering whether the watch detects my footsteps as I run downhill on that particular stretch, rather than my heart rate? However, my cadence is around 170, so far lower than the HR recorded.
I was initially worried about my heart health after contacting the Garmin team, but with numbers as high as 230 I'm thinking it's more likely to be a problem with the watch. It's really messing with my HR zones and VO2 max!