How do polar heart watches work?

Most heart rate watches are EKG (electrocardiogram) based. Either they come with a strap with EKG electrodes that goes around your chest. This picks up the signals and wirelessly transmits the readings to your watch where you can look at it. Another version is where the electrodes are built into the watch. This is a strapless version but you have to touch the electrodes with your other hand to get the signal.

-- Haider

Houston, TX