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How do I start a workout? — Open Four by Four on your iPhone, tap “Start Workout,” and the app will guide you through the full Norwegian 4×4 protocol. Make sure your Apple Watch is paired and worn.
Why isn't my heart rate showing? — Ensure your Apple Watch is snug on your wrist and that you've granted Four by Four access to HealthKit. Open the Health app → Sharing → Apps → Four by Four and enable Heart Rate.
Can I use Four by Four without an Apple Watch? — An Apple Watch is required for real-time heart rate coaching. The app uses live heart rate data to guide you through each interval.
How are my heart rate zones calculated? — Zones are based on your age using the Karvonen formula. You can update your age in the app's settings to recalculate your zones.
Where is my workout data stored? — All data stays on your device. Workouts are saved to Apple Health and to local storage on your iPhone. Nothing is sent to external servers.
How do I delete my data? — Deleting the app removes all locally stored data. Workouts saved to Apple Health can be managed through the Health app on your iPhone.
Still need help? Reach out and we'll get back to you as soon as we can.