Wrist-based heart rate measurement

Your watch measures your heart rate from the wrist with the Polar Precision Prime™ sensor fusion technology. This new heart rate innovation combines optical heart rate measurement with skin contact measurement, ruling out any disturbances to the heart rate signal. It tracks your heart rate accurately even in the most demanding conditions and training sessions.

Although there are many subjective clues as to how your body is doing during exercise (perceived exertion, breathing rate, physical sensations), none of them are as reliable as measuring heart rate. It is objective and affected by both internal and external factors—meaning that you will have a dependable measure of your physical state.

Wearing your watch when measuring heart rate from your wrist or tracking your sleep

To measure wrist-based heart rate accurately during training, when using the Continuous heart rate and Nightly Recharge features or while tracking your sleep with Sleep Plus Stages make sure that you wear the watch correctly:

  • Wear your watch 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 watch should not be able to move on your arm. 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.
  • For most accurate heart rate measurement, we advise you to wear your watch for a few minutes prior to starting the heart rate measurement. Also it's a good idea to warm up the skin if your hands and skin get cold easily. Get the blood going before starting your session!

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 them as they may prevent accurate readings.

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 if you’re looking for supreme accuracy in your training. Your watch is compatible with Bluetooth® heart rate sensors, like Polar H10. The Polar H10 heart rate sensor is more responsive to rapidly increasing or decreasing heart rate, so it’s the ideal option also for interval type of training with quick sprints.

To maintain the best possible performance of the wrist-based heart rate measurement, keep your watch clean and prevent scratches. After a sweaty training session, we recommend that you wash the watch under running water with a mild soap and water solution. Then wipe it dry with a soft towel. Let it fully dry before charging.

Wearing your watch when not measuring heart rate from your wrist or tracking your sleep/Nightly recharge

Loosen the wristband a bit for a more comfortable fit and to let your skin breathe. Wear the watch just as you would wear a normal watch.

Every once in a while it’s a good idea to let your wrist have a breather, especially if you have sensitive skin. Take off your watch and recharge it. This way both your skin and your watch can have a rest, and be ready for your next training event.