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Zenith relies on standard Apple Health permissions. During initial setup, Zenith requests read-only access to categories such as Heart Rate, HRV, Sleep, Steps, Active Energy, Cardio Fitness, and Resting Heart Rate.

If you missed granting permission or want to update access later:

1. Open the Settings app on your iPhone.
2. Scroll down and tap Health → Data Access & Devices.
3. Tap Zenith from the list.
4. Toggle on individual health categories or tap Turn On All.

Daily Strain and Recovery scores require adequate heart-rate and workout telemetry from your Apple Watch or supported wearable.

• Recovery Score: Calculated each morning based on your overnight Resting Heart Rate (RHR), Heart Rate Variability (HRV), and Sleep duration. If overnight sleep or HRV data was not recorded by Apple Health, Recovery may show as pending.
• Strain Score: Accumulates continuously throughout the day based on heart rate zones and active workout energy. If you haven't recorded workouts or heart rate readings today, your Strain score will remain low.

100% On-Device: Zenith does not have developer servers, cloud databases, or remote accounts. All computations take place locally on your iPhone.

Your Health records stay inside Apple Health, while Zenith-specific settings and blood test entries are stored inside your iPhone's protected local app container utilizing iOS hardware encryption.

Zenith estimates Biological Age by analyzing physiological markers from Apple Health (such as VO2 Max, Resting Heart Rate, HRV, Body Fat %, and Sleep consistency) combined with optional clinical blood test parameters (such as Lipid profile, Glucose, hs-CRP, and HbA1c).

Our algorithms evaluate these biological metrics against validated epidemiological baseline distributions to calculate your physiological age gap compared to chronological age.

To enter lab results:

1. Open Zenith and navigate to the Biology tab.
2. Tap Add Lab Result or select a specific biomarker (e.g., Total Cholesterol, Fasting Blood Glucose).
3. Enter the value and test date from your lab report.

Blood test data is completely optional and is saved exclusively in Zenith's local encrypted storage on your iPhone. It is never uploaded to any remote server or third party.

Zenith includes full data control features in the app settings:

1. Open Zenith and tap Settings (gear icon).
2. Scroll to the bottom section labeled Danger Zone.
3. Tap Delete All Zenith Data and confirm.

This permanently erases all local Zenith settings, Biological Age history, and blood test records. Note: This action does not delete original records from Apple Health.

No. Zenith is a personal wellness application designed strictly for general health awareness and lifestyle tracking. Outputs such as Strain, Recovery, and Biological Age are informational estimates.

Zenith is not intended to diagnose, treat, cure, or prevent any medical condition or disease. Always consult a qualified medical professional for health concerns.

Zenith reads sample data directly recorded in Apple Health by your Apple Watch or connected health accessories. Differences between apps can occur due to:

• Different sleep window calculation methods (e.g. In Bed vs. Asleep stages).
• Baseline window periods (Zenith uses a weighted 14-day rolling baseline for HRV and Resting Heart Rate).
• Data source prioritization in Apple Health settings.