Can Apple Watch provide complete data on the heartbeat for thousands of seconds during the workout or when using the "Breathe" app?
When I exported data from Apple Health it shows the following data. The rows 195, 196 & 197 are measurements taken through the "Breathe" app.
Thank you for your answers,
What is the API question?
Heart rate data from my Apple Watch Series 4 are very inaccurate, as was the case on my earlier watches. For a while now I've been using the Watch's Workout app while running and comparing that with workout data from an iPhone app that uses a Polar H10 heart monitor strap. For example, on yesterday's run the Watch recorded an average heart rate of 148 bpm, whereas the Polar device data was for 123 - which is almost certainly accurate (I'm 72 with heart issues so don't go very fast). I have several years' worth of data from monitor straps (starting with Garmin), so I know what my heart rate should look like: it's understandably declined over the years as I've aged.
Most heart monitor straps record every heartbeat and transmit its time interval as milliseconds, along with the current heart rate (actually a moving average of the intervals in bpm) to a tethered smart device. Most modern straps use Bluetooth LE and therefore can be read by the Watch Workout app, your app and/or an iPhone app.
Best wishes and regards, Michaela
Sorry, in my previous answer I didn't explicitly answer your question about the Watch providing complete data for heartbeats for thousands of seconds. Some time ago I looked at the heartbeat data in the Health repository on the phone (as reported from the Watch) and more recently at heartbeat data in workouts on the phone: there appears to be no "complete" dataset, only periodic (every few seconds) data points. This perhaps is understandable given that for an hour's exercise there could be 5-10 thousand heartbeats, requiring a lot of storage and processing on the Watch. This lack of complete data, and my observed inaccuracies in the Watch's heart rate reports, is why I can't reply on the watch data and must use a third-party heart monitor chest strap.
In my case, with arrhythmia issues, my phone app, using realtime input from the chest strap, can alert me during a run when arrhythmia stars to occur and/or when my safe heart rate maximum has been exceeded. I'm also able to then share the data with my medical advisors.
Once again, best wishes and regards, Michaela
PS - I gather that you're in Europe (Czech Republic?): in which case I wish you well in these troubled times.
Your app should not be displaying heart rate with three decimal point accuracy in its UI, regardless of how the data is stored in HealthKit.