How Apple Watch measures your heart rate

Apple Watch is the smartwatch millions are waiting for to arrive. Packing several amazing features, Heart Rate monitor is one of the many health-centric options integrated in the Apple wearable.

Many smartwatches, smart bands and smartphones integrate heart rate monitor feature to gauge the heart rate but there is no accurate way so far. Apple Watch attempts to get a near accurate estimate of the heart rate. A freshly published Apple Watch support page shares details on how the Watch measures heart rate.

The heart rate sensor in the Watch uses a complex method called Photoplethysmography to measure heart rate every 10 minutes. This technology on Watch is implemented though green LED lights coupled with light-sensitive photodiodes. So every 10 minutes, the green LED lights blink at the rate of hundreds of times per second, it calculates your heartbeat through the blood flow in your wrist.

Alternatively, the Infrared light also measures heart rate every 10 minutes and only in case of inadequate reading, the sensor switches to the green LED lights.

The adequate heart rate reading and data also depends on how the watch has been worn on the wrist. Apple advises to wear the Watch snug on your wrist and not let it hang around loosely. However, the sensor may still struggle even in case of irregular wrist motions and skin perfusion in different environments. For instance, working out with weights in a room with low temperature may not necessarily give accurate reading.

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