- Non-standard wearing manners such as light leakage caused by imperfect fitting, arm swinging, and slight movement of the watch on the skin can affect the measurement of heart rate signals. Wearing the watch too tightly, raising the arm, and making a fist can also affect blood circulation and thereby affecting heart rate signals.
- The correct way of measurement is to keep your arm flat, relax, still, and make sure that the watch is close to your arm. Notes: With the correct wearing manner, individual differences in skin color, hair, tattoos, and scars may also affect heart rate monitoring.
(The heart rate of people with brown skin and black skin as measured by watch may vary in accuracy, because darker skin colors can absorb green light.)