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.

Note that the reliability of the measurement, especially in cold conditions, depends on the blood flow in the area that the sensor is located in. The blood flow is affected by the skin temperature of your hands and wrist area, and therefore you can help the measurement by keeping your fingers and palms warm and your wrist covered.

If you have tattoos on the skin of your wrist, avoid placing the sensor right on them.

If you've followed the instructions above and are still having trouble, you can try wearing the device on your other wrist to see if that helps.

What type of sport are you doing?

Swimming: When you're recording a swimming session with your Polar device, it’s important to wear the device snugly on your wrist (even more snugly than in other sports). This way you can ensure the best possible accuracy of your heart rate data. Although water may prevent the wrist-based heart rate measurement from working optimally, you can still monitor your average heart rate and heart rate zones during your swimming sessions, get accurate calorie burn readings and the benefits of the Smart Coaching features.   

The Polar OH1 optical heart rate sensor is an optimal solution for recording your heart rate during your swimming sessions. It allows you to store your heart rate data in its internal memory and then sync the data with the Polar Flow or Beat app afterwards. The Polar OH1+ product package includes a swimming goggle strap clip that you can wear against your temple to measure your heart rate accurately while swimming.

Note that you can't use a Polar heart rate sensor with a chest strap with the Polar device (A360, A370, Ignite, M200, M430, M600, Vantage M, Vantage V, Grit X) 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.

Strength training: If you perform activities that cause extreme pressure on your wrists, such as weightlifting or pull-ups, your heart rate may be more difficult to detect from the wrist. Move your device up a few centimeters as wearing it higher on your wrist may improve the heart rate signal.

Racket sports: Activities that involve irregular hand movements, such as racket sports, make it harder to get an accurate heart rate reading from the wrist. When playing these sports, you can switch the handedness of the tracker and change it to the non-hitting hand.

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, the Polar OH1 optical heart rate sensor is a great alternative to wrist-based optical heart rate measurement. You can wear the Polar OH1 on either your forearm or upper arm allowing you to try out different locations to find a location that consistently finds your heart rate. When you’re looking for the best possible accuracy for example for sprints, interval and strength training, we recommend using a Polar H10 heart rate sensor with a chest strap.

Regardless of the sport, you can always use the device to monitor your average heart rate and heart rate zones during training, get accurate calorie burn readings, and use other Polar Smart Coaching features.

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:

  • 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 devices 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.

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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