I've noticed than on some occasions the heartbeat monitor give a result in less than a second, is that normal? To clarify, I'm talking about the heart monitor app, not the ecg app. I don't see how a heartbeat can be measured in less than a second?
Is your watch set to only take manual readings? Else it'll just be showing you what it's currently recording as it records 24/7.
Though for an answer. Watch the green flashy light on your watch. Thats how oftern it checks heart rate. Not every second. So it can get data from a tiny amount of time, then extrapolate that into seconds.
No this happens even when I take a manual reading (by tapping the "Measure" button. Normally it would say "preparing" then start taking a reading which takes about 10 seconds or so. But randomly it takes no time at all, it's just instant.