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Accuracy of wrist-based heart rate measurement

Optical heart rate measurement from the wrist is an easy and convenient way to track your heart rate. To get the best results, please keep in mind factors that may affect heart rate measurement:

  • The watch must be worn directly against your skin. No clothing, however thin, can be between the sensor and your skin.
  • The watch may need to be higher on your arm than where watches are normally worn. The sensor reads blood flow through tissue. The more tissue it can read, the better.
  • The optical sensor may not provide accurate heart rate readings for swimming activities.
  • Arm movements and flexing muscles, such as gripping a tennis racket, can change the accuracy of the sensor readings.
  • When your heart rate is low, the sensor may not be able to provide stable readings. A short warm up of a few minutes before you start the recording helps.
  • Skin pigmentation and tattoos may block light and prevent reliable readings from the optical sensor.
  • For better accuracy and quicker responses to changes in your heart rate while exercising, we recommend using a compatible chest heart rate sensor such as Suunto Smart Sensor.
  • Heart rate readings may vary based on an individual's physiology, age, and other factors. Some people, because of their physiology, cannot get stable, accurate heart rate readings. Your level of activity may also adversely affect your heart rate reading.


WARNING:
Optical heart rate sensor technology is currently not as accurate or reliable as measuring heart rate from the chest. Your actual heart rate may be higher or lower that the optical sensor reading.