I’ve suspected a few times that the Smart Sensor was recording incorrect values. Today I saw it for sure. I read 160 bpm on my watch during the final sprint, and 160 bpm also appears as the peak in the data, but the heart rate graph shows 148 bpm as the maximum. At the corresponding point (marker), it was only 137 bpm.
[image: 1754243175833-screenshot_2025-08-03-19-35-44-304_com.stt.android.suunto.jpg]
That was a total of 700 meters of elevation, and at the end the climb gets even steeper. You can see how the performance increases, but the heart rate even briefly dips into the green zone. And as I said, around that mark I saw 160 bpm in the red zone on the watch live. The previous green tip pointing downwards is also wrong.
What is being recorded, or what do I see on the watch? In any case, it’s not the same thing.
Another example is something I see sometimes. A straight line over 2 minutes followed by a dip in sustained performance
[image: 1754243783136-screenshot_2025-08-03-19-34-03-032_com.stt.android.suunto.jpg]
Am I expecting too much from the technology? But what exactly happens if I see something different on the watch than what’s shown in the recording? Did the watch sensor record while I was seeing live data from the Smart Sensor? I can’t think of any other explanation. It was exactly the kind of situation where an optical sensor is having problems. A cold wind suddenly blew up high, and my skin reacted to the cold.
(Recorded with the Suunto Run)
