Hi all, We are a university research group developing a heart-rate-based physical activity score. We need heart rate at 20-second intervals or better, recorded passively (24/7, without the user starting a workout), and read via HealthKit. Apple's support page says that Apple Watch Series 12 and Ultra 4 measure heart rate continuously, as often as every 5 seconds. Our questions: Are these continuous measurements stored as HKQuantitySamples (heartRate) in HealthKit, so a third-party app can read them at that resolution? On older models, what is the typical interval of passive heart rate samples in HealthKit? During a workout (HKWorkoutSession), what is the typical interval of stored heart rate samples? Any experience or official guidance is very welcome. Thank you!

Interval of passive heart rate samples (in HealthKit)

Hi all,

We are a university research group developing a heart-rate-based physical activity score. We need heart rate at 20-second intervals or better, recorded passively (24/7, without the user starting a workout), and read via HealthKit.

Apple's support page says that Apple Watch Series 12 and Ultra 4 measure heart rate continuously, as often as every 5 seconds. Our questions:

Are these continuous measurements stored as HKQuantitySamples (heartRate) in HealthKit, so a third-party app can read them at that resolution?
On older models, what is the typical interval of passive heart rate samples in HealthKit?
During a workout (HKWorkoutSession), what is the typical interval of stored heart rate samples?

Any experience or official guidance is very welcome. Thank you!