Health & Fitness
Threshold
Zones anchored to your threshold, not to 220 minus your age.
iPhone ยท Watch
The app
Zones anchored to your threshold, not to 220 minus your age.
Heart-rate zone training for Apple Watch and iPhone, built on lactate threshold rather than the borrowed percentage-of-maximum model most zone apps still use.
The incumbent in this category puts custom zone boundaries behind a paywall and derives them from a formula that was never meant to be precise. Threshold inverts both. Accessibility, dark mode and localisation were in scope from the first commit.
Features
What it actually does.
A lactate-threshold zone model
Live zone feedback mid-workout
Journeys and splits
Accessible from day one
Privacy
Workouts are read from Apple Health on-device and stay there.
StorageOn device
On-device
Apple HealthRead only
HealthKit, on-device
LocationOnly when used
Used during workouts for route and pace
AnalyticsNone
No analytics of any kind.
Third partiesNone
No third-party SDKs, trackers or advertising.