Build Workout Zone Coaching With HealthKit

This article provides a technical guide for developers on how to implement workout zone coaching with HealthKit in iOS 27 and watchOS 27. It explains how HealthKit now supports heart-rate and cycling-power workout zones directly, allowing apps to track time spent in each zone per workout or per activity. The article covers using HKWorkoutZoneGroup, HKWorkoutZoneConfiguration, and zoneDurations to build per-activity zone insights, helping runners understand intensity, recovery, and plan adherence. It includes code examples and references to Apple's WWDC26 session and documentation, focusing on practical implementation rather than theory.