How to add "Estimated Time in Each Heart Rate Zone" info to my custom HKWorkout when viewed in Apple Fitness app?

Hello,

I’m currently developing a fitness app for watchOS that lets a user to manually set a desired heart rate target zone (enter numbers representing the lower and upper boundaries) and start a workout (right now it’s only “Other” type). After that my app monitors user’s heart rate and alerts them when they’re out of zone.

When user ends the workout, the info about this workout appears on “Fitness” iOS app, and user can see the workout data like Workout Time, Active and Total Calories, Avg. Heart Rate. Also user can see Heart Rate chart with info how their heart rate was changing during a workout (see the Figure 1).

Now to the question.

When user clicks “Show More” button above the Heart Rate chart, they can see the same Heart Rate chart and another one, with Post-Workout Heart Rate (see the Figure 2).

But there is no “Estimated time in each heart rate zone” as one can see in the workout’s details that were recorded from Apple’s workout (watchOS “Workout” app, for a workout of “Other” type as well). Please see the Figure 3.

The question is: is it possible to add “Estimated time in each heart rate zone” to workout recorded via my third-party app so it would look like on the Figure 3 in "Fitness" iOS app, and if it's possible, what steps should I undertake to implement this ?

Thanks in advance!

I posted the screenshots in the replies to the post, because otherwise I was not able to submit a post ("sensitive language" warning, I suspect it's because of the ids in the attached screenshot's urls)

Replies

Figure 1, general info about the workout from my app in "Fitness" app:

Figure 2, detailed info about Heart Rate during the workout from my app in "Fitness" app:

Figure 3, detailed info about Heart Rate with heart rate zones during the workout recorded by watchOS "Workout" app in "Fitness" app: