Training with wrist-based heart rate
Heart rate training
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.
Measuring heart rate with your M430
Your Polar M430 has a built-in heart rate sensor that measures heart rate from the wrist. Follow your heart rate zones directly from your device, and get guidance for the training sessions you've planned in the Flow app or web service.
To measure wrist-based heart rate accurately you need to wear your M430 snugly on top of your wrist, just behind the wrist bone (see the picture on the right). The sensor on the back must be in constant touch with your skin, but the wristband should not be too tight to prevent blood flow. For most accurate heart rate measurement, we advise you to wear your M430 for a few minutes prior to starting the heart rate measurement.
If you have tattoos on the skin of your wrist, avoid placing the sensor right on it as it may prevent accurate readings.
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!
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 a better measurement of your heart rate.
When you're recording a swimming session with your M430, water may prevent the wrist-based heart rate measurement from working optimally. But the M430 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 the M430 when swimming because Bluetooth doesn't work in water.