How is Heart Rate Measured?

If you're using an Apple Watch, Paddle Logger can show your heart rate for the duration of your trip. Your heart rate is also used to estimate the number of calories burned.

We rely on the data that the Apple Watch's heart rate sensor records. Apple Watch uses green LED lights paired with light‑sensitive photodiodes to detect heart rate. 

Multiple factors can affect the heart rate sensor's accuracy, such as:

• Skin perfusion (how much blood flows through your skin), if you have poor circulation or are cold you may find the reading inaccurate
• Having a tattoo on the area covered by the sensor, this can block light from the sensor reaching the skin
• Irregular movements
• Sunlight interfering with the sensor
• Not having the right fit, having your watch too tight or too loose can lead to inaccurate measurements
• Ensure the sensor is on the top of your wrist, some people prefer to wear their watch with the face on the inside of their wrist but this will not record accurate heart rate data

External Heart Rate Monitors

You can connect your Apple Watch to external heart rate monitors such as Bluetooth chest monitors. Bluetooth accessories must be paired with your Apple Watch and not with the Paddle Logger app. 

1. Put your external Bluetooth heart rate monitor in Pairing Mode following the instructions it came with
2. On your Apple Watch, tap Settings > Bluetooth. Your Apple Watch will search for nearby Bluetooth accessories
3. Choose your Bluetooth accessory
4. If prompted, input a PIN or passkey