Apple Watch ECG won't work when heart rate is high
My Apple watch won't capture an ECG when my heart rate is over about 135 bpm. Could this be by design?
Sometimes after a strenuous hill climb while hiking or cycling, when my heart rate was high, I've tried to use the Apple Watch ECG, but for several minutes it can't get any data that looks remotely like my pulse, which feels strong and regular. Only after my heart has slowed down does the Apple watch start to see a rhythm, and it says it's normal sinus rhythm. To get an ECG while my heart rate was still high, I've tried sitting very still, resting my arms on my lap or a wooden fencepost, ensuring the only contact from my opposite arm is my finger touching the crown, leaving my skin sweaty, wiping the sweat away, and even placing the watch on my knee instead of my wrist, but nothing works. I haven't had any feeling of muscle spasms that might account for the chaotic data trace.
Could it be that the Apple Watch ECG software is designed to detect frequencies over about 135 cycles per minute overlaid on a frequency below about 135 bpm, and therefore it can't work when the heart rate itself is higher than about 135?
