Can I compute HR zones from hr_samples?

hr_samples from the Activity event are the right input for computing your own zones.

hr_samples from the Activity event are the right input for computing your own zones. Each is a heart rate reading with a timestamp, so set your thresholds and bucket samples by time.

• Apple does not populate hr_zone_data but does send hr_samples, so computing zones from samples is sound.

• Sample cadence is not a fixed interval; it is whatever the device recorded, so derive time-in-zone from each sample's timestamp rather than assuming a fixed rate.

• Polar sends hr_samples and also populates hr_zone_data when the activity carries it.