ELi5: How do those metal bits on the handles of cardio equipment measure your heart rate through your hands?
In: 8
As a fellow with dry hands: they don’t.
They use the bit of moisture most people have on their hands to measure resistance from one hand to the other. Along that path is your heart and its beating changes the resistance so by measuring it over time the device can tell your heart rate.
But if your hands are dry then they can’t get a good electrical connection and don’t read anything.
Blood conducts better than tissue due to the water in it. Those pads measure your skin resistance, which varies with your heartbeat