Open reThrive and sign in with Apple or Google. Your account is created automatically on first sign-in.
During onboarding, you'll see the data sources screen. Select Apple Health.
Grant all requested permissions. reThrive needs these to calculate your True Age:
Heart rate (for resting heart rate)
Heart rate variability (HRV)
Cardio fitness (VO2max)
Body measurements (weight, body fat, lean body mass)
Activity data (steps, workouts)
Sleep data
After granting permissions, you'll return to reThrive. The app will begin syncing your data immediately.
If you need to change permissions later, go to Settings → Health → Data Access & Devices → reThrive.
After connecting, navigate to your Home screen to see:
Which biomarkers have enough data
Which biomarkers need more data
The This Week section shows if you'll have enough data for next week's True Age update
reThrive needs consistent data from your wearable to calculate True Age.
How True Age works:
Updates every Monday using data from the previous 4 complete weeks (Monday to Sunday)
Requires minimum data across those 4 weeks to calculate
Minimum data requirements:
RHR and HRV: 4+ days with readings across the 4 weeks
VO2max: At least 1 reading across the 4 weeks
LBMI: At least 1 reading across the 4 weeks (lean body mass, or weight + body fat %)
Confidence levels:
Your True Age will show High, Medium, or Low confidence based on data completeness and recency:
High confidence: 24+ days of RHR/HRV, VO2max/LBMI readings less than 1 week old
Medium confidence: 14-23 days of RHR/HRV, VO2max/LBMI readings 1-2 weeks old
Low confidence: 4-13 days of RHR/HRV, VO2max/LBMI readings 2-4 weeks old
If you already have historical data in Apple Health from your wearable, you may see your True Age immediately. Your initial confidence depends on how complete and recent your data is.
If you're starting fresh, wear your device consistently to build up data. You'll see your first True Age once you have the minimum requirements.
Resting heart rate and HRV:
Wear your device while sleeping. Most wearables automatically track these metrics during sleep or rest periods.
VO2max:
Do cardio workouts with your device. Most wearables calculate VO2max from outdoor runs, walks, or cycling.
Lean body mass index:
Either connect a smart scale that syncs to Apple Health or enter Lean Body Mass (or Weight and Body Fat %) measurements manually. If you don’t know your Lean Body Mass, you can use online calculators (like the one here). Make sure your height is set in your profile.
Timeline: Updates every Monday
Once you have enough data across 4 complete weeks, your True Age will appear on your Home screen and Age tab.
Your confidence level (High, Medium, or Low) shows how reliable your True Age is based on data completeness and recency. Confidence improves when you have more frequent RHR/HRV readings and more recent VO2max/LBMI measurements.
Not seeing all your data?
Make sure your wearable is syncing to Apple Health
Check that all permissions are enabled in Settings → Health → Data Access & Devices → reThrive
Trigger resynchronization from Settings → Apple Health in the reThrive app
