Interval Training Timer for iPhone & Apple Watch
How do I set my max heart rate? Go to Settings and toggle “Manual Override” under Heart Rate Max. If you don’t override it, the app estimates your HRmax from your age using the Tanaka formula (208 - 0.7 × age).
Why isn’t my heart rate showing during the workout? Heart rate data requires an Apple Watch paired and running the companion app. Make sure you’ve granted HealthKit permissions when prompted during onboarding.
Can I change the interval durations? The 4x4 protocol uses fixed 4-minute intervals and 3-minute recoveries. You can adjust warm-up and cool-down durations in Settings.
Where is my workout data stored? All workout data is saved to Apple Health on your device. The app has no server, no accounts, and no analytics. Your data never leaves your device.
The app crashed or something isn’t working. Please contact us using the email below with a description of what happened. Include your iPhone model and iOS version if possible.
For bug reports, feature requests, or questions: alicedevwin@icloud.com