Troubleshooting optical heart rate measurement

Are you wearing your Polar device correctly?

To be able to get reliable heart rate measurements from your wrist, make sure that you wear the Polar device correctly:

  • Wear the Polar device on top of your wrist, at least a finger’s width up from the wrist bone (see the picture below).
  • Tighten the wristband firmly around your wrist. The sensor on the back must be in constant touch with your skin and the Polar device should not be able to move on your arm. Movement between the Polar device and your skin can interfere with the readings.
  • A good way to check that the wristband is not too loose is if you push the wristband lightly up from both sides of your arm and make sure the sensor doesn’t lift from your skin. When pushing the wristband up you shouldn't see the LED light shining from the sensor.

During training you should slide the Polar device further up from the wrist bone and wear the wristband a bit more tightly to try to minimize any extra moving of the device. Give your skin a few minutes to adapt to the Polar device before starting a training session. After the training session, loosen the wristband a bit.

If you have tattoos on the skin of your wrist, avoid placing the sensor right on it as it may prevent accurate readings. Also, if your hands and skin get cold easily, it's a good idea to warm up the skin under the sensor.

What type of sport are you doing?

In sports where it's more challenging to keep the sensor stationary on your wrist or where you have pressure or movement in muscles or tendons near the sensor, we recommend using a Polar heart rate sensor with a chest strap to get better measurement of your heart rate.

Swimming: When you're recording a swimming session with your Polar device, water may prevent the wrist-based heart rate measurement from working optimally. But Polar device will still collect your activity data from your wrist movements when swimming. Note that you can't use a Polar heart rate sensor with a chest strap with Polar device when swimming because Bluetooth doesn't work in water.

Indoor cycling: Because the indoor bicycle is stationary and your hand is not moving, signal artifacts resulting from gripping the handle bar at the pedaling rate may be falsely identified as heart rate. Move your device up a few centimeters as wearing it higher on your wrist may improve the heart rate signal. For optimal heart rate measurement, use a Polar H10 heart rate sensor which measures heart rate very accurately during indoor cycling.

Are the heart rate signals unusually high or otherwise abnormal?

Adjusting the wristband tighter around your wrist may help. Possible causes of abnormal heart rate readings during exercise might be:

  • In cold weather the blood vessels in the skin constrict, less on some people and more on others. The optical heart rate sensor may have difficulty to detect the variations in the intensity of your blood flow if the effect of the cold weather is greater on your veins.
  • If a certain sport profile constantly displays too low heart rate readings, check if you have set the sport profile to display heart rate in percentages of your maximum heart rate (HR%) instead of beats per minute (HR). For more information on how to edit sport profile settings, see the user manual for your Polar device.
  • Polar products are not designed to detect arrhythmia or irregular rhythms and will interpret them as noise or interference. In most cases the Polar training computers work fine for persons with cardiac arrhythmia, but in some cases (many abnormal heart beat intervals) arrhythmia may cause incorrect heart rate readings.


Have you given the Polar app permission to use sensors?

To turn the Polar app's sensor permission on and off:

  1. Swipe down from the top of the home screen to access the Quick settings menu.
  2. Tap the settings icon.
  3. Tap Apps & notifications.
  4. Tap App permissions.
  5. Tap System Apps
  6. Scroll the list to find and tap Polar.
  7. Tap Sensors to toggle between turning them on (the switch is blue) and off (the switch is gray).

OH1 does not detect my heart rate, what can I do?

To maintain the best possible performance of the optical heart rate measurement, keep your OH1 clean and prevent scratches. The measurement is based on tiny changes in light intensity, and even a small amount of dirt on the sensor at the back of the device can reduce its performance. Similarly, scratches on the sensor can scatter the light from the LEDs into unwanted directions and weaken the device’s performance.

Movement between the OH1 and your skin can interfere with the readings. That is why it’s important that you wear the armband snugly on around your forearm or upper arm, not around your wrist. Try out different locations on your forearm or upper arm to find a location that consistently finds your heart rate. The OH1 must be touching your skin but not so tightly that it prevents circulation or feels uncomfortable.

Activities that involve irregular hand movements, such as racket sports, make it harder to get an accurate heart rate reading from your arm. When playing these sports, you can switch the handedness of the OH1 and change it to the non-hitting hand. If you perform activities that cause extreme pressure on your arms, such as weightlifting or pull-ups, your heart rate may be more difficult to detect from the arm.

In cold conditions, blood circulation on the skin may become too weak for the sensor to get a proper reading. You can solve this by warming the skin on your arm or by doing some exercise to increase skin temperature.

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