The heart rate monitor on the Active2 is abysmal at best. I specifically purchased this to monitor my heart rate during exercise and daily activities. During exercise, the Active2 most times drops the heart rate which is extremely frustrating. If that isn't bad enough, the actual accuracy of the heart rate monitor is quite poor. I had a instance of tachycardia, that was nurse verified at 153bpm, but my good old Active2 said my heart rate was 93bpm during the whole episode.
I've have worn a pulse oximeter and an Apple Watch at the same time to compare to my Active2. The Active2 was at least 40bpm different than both the Apple Watch and pulse oximeter. Quite honestly its embarrassing at how poorly this watch tracks heart rate.
I have loved my Samsung phones, but the experience with the Active2 makes me want to look into Apple products.