Only because optical heart rate sensors aren't very accurate under many real world conditions that have nothing to do with the quality of the sensors, other har

Only because optical heart rate sensors aren't very accurate under many real world conditions that have nothing to do with the quality of the sensors, other hardware, or the software. There's a good long history of medical research here, and not a lot of reason to believe that someone is going to develop a medically useful wrist strap based optical sensor.