Fitness trackers and smartwatches have become so advanced that we now expect them to give us detailed information on our heart rate by default. The optical heart-rate sensor was once a unique feature that commanded a premium, but now even budget bands track your beats per minute while you work out.
Now these devices are moving beyond basic heart-rate-monitoring during workouts. Any Apple Watch running watchOS 5 can tell you when your heart rate is too high or too low when you’re not exercising, which could be a sign of a serious health issue.
