How are the heart rate zones divided while running with the watch?

The heart rate zones of the watch can be divided into Relaxed, Light, Intensive, Aerobic, Anaerobic and VO2 max.
For example, if a user is 25 years old, the maximum heart rate = 220 - current age = 220 - 25 = 195, and if the heart rate value measured by the watch lies between 50% - 60% of the maximum heart rate, the watch will take it as the light zone. If it lies between 60% - 70%, it's the intensive zone, and so forth, and that's how we determine to divide HR zones.