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I can tell you that it just counts beats per minute. It won't record arrhythmias or anything like that. Even at bpm, it's only an approximation as the watch is not FDA approved as a medical device. If that's what you're asking.
 
Right after she tapped the crown it briefly displayed the heart rate before going to the home screen. So it appears to be a software glitch to me.
 
you would probably be better with a bluetooth strap on your chest connected to your iphone than using the watch optical reader.
 
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