Optical vs electrode heart rate sensors, how they differ
PPG light measurement against direct ECG electrodes.
- Answers
- What is the difference between optical and chest strap heart rate monitors?
- Topics
- apple · data · health · heart · sensors · sport · watch
- Full article on willem.com
- https://willem.com/en/2019-07-15_optical-vs-chest-strap-heart-rate-monitors/
Summary
A chest strap captures your heart's electrical activity through electrode pads, like a hospital ECG: accurate and power efficient. An optical wrist sensor reads LED light refracted off your blood, convenient but more power hungry and sensitive to bright sunlight.
Full text
There are three ways to measure heart rate: manually, counting your pulse for ten seconds and multiplying by six; with an electrode sensor; or with an optical sensor. Electrode sensors capture the electric activity of the heart, the same principle as a hospital ECG. A hospital connects up to twelve pads, a chest strap uses two on a band. Once it has a signal it is accurate and power efficient, which is why hospitals and professional athletes use it. Optical sensors shine green or red LED light into your wrist and analyse the light refracted off your flowing blood, a photoplethysmogram or PPG. The processing costs more power, and bright sunlight can disturb the reading if the sensor is not snug on your wrist. My advice: combine them. Use a chest strap to capture a workout in detail and an optical wearable to follow your recovery in the hours afterwards.