are these things even accurate? How can it take accurate blood pressure? Heart rate? Etc? I understand they can estimate calories burned and such- but even that wouldn’t be accurate as your pace while excising usually speeds up and drops over the course of the exercise time- Does a ‘smart watch’ monitor the speed and adjust it’s calculations for lost calories?
The pulse rate monitors are pretty accurate, mirroring the technology you see in the fingertip monitors.
So far, they cannot do blood pressure, but they are quite accurate for heart rate. They can also do blood oxygen levels but are not certified to do so, thus Apple does not allow their own Apps or third party Apps to do that yet. Caloric usage can be fairly accurately estimated by motion and speed or heart rate. . . and the smartwatch does indeed adjust its calculations for caloric usage based on what the user is doing based on motion and heart rate.
Until a smartwatch can compress a blood flow until it stops and starts with pressure, there is literally no way for it to accurately measure blood pressure. The battery capacity inherent in any wearable and space available for such battery power density would not lend themselves to the power to drive a pressure cuff pump. It will probably require a break through in sphygmomanometer technology and/or remote sensory technology before we would be able to test BP without compression. Proposals have been made that would require an injectable sensor be installed within an artery which could measure the difference pressure between the systolic (high pressure) and diastolic (low pressure) of the pumping action of the heart, which could be read by an external wearable technology device, but that strikes me as a bit too invasive just to gain a little convenient immediate information for non-medically necessary usage a wearable watch or other device would provide a user.
That being said, the Apple Watch has, in several instances, saved the lives of users who noticed that after exercise, their heart rates did not return to normal rates as they should. In at least one instance I am familiar with, this involved a teenage athlete, who had he not noticed the elevated heart rate through his Apple Watch and gotten immediate medical attention, would not have survived the condition.