Informs the optional resting-heart-rate VO2 estimate. We treat this as a low-confidence input, especially outside well-trained populations.
About & Methodology
Where the estimate comes from
Vitality Arc is a wellness estimator built from public formulas, published research, and product heuristics. It is designed to show a plausible range, not deliver a diagnosis or an exact forecast.
Important context
Some parts of the app come from widely used public formulas. Other parts, especially future trajectories, risk windows, and coaching targets, are research-informed approximations built for consumer planning.
What is directly formula-based
These are the parts of the app where the math comes from a known public formula, test equation, or published standard.
Used when a user does not know their measured maximal heart rate.
Informs the MET values used for activity thresholds and readiness guideposts.
Supports the use of the Cooper test as a practical field estimate, while also highlighting that field tests carry more error than lab testing.
Informs how we think about age- and sex-adjusted cardio guideposts.
What informs the guideposts
These papers and guidelines do not map one-to-one onto the whole product, but they inform how we think about cardio fitness, steps, strength, and general activity targets.
Informs our weekly activity framing and the general recommendation to include both aerobic and muscle-strengthening activity.
One of the reasons VO2max sits near the center of this estimator.
Supports grip strength as a useful optional strength input and explains why we treat it as a high-signal consumer metric.
Supports using daily steps as a practical everyday health signal.
Adds more support for daily steps as a practical movement signal.
Helps frame why grip is clinically interesting, but also why age context matters.
Part of the rationale for making future trajectories bend more sharply at older ages.
A reminder that heart-rate-based VO2 estimates have important limits and can drift in older adults.
What the app does not claim
Not a diagnosis
The app does not diagnose disease, screen for illness, or replace a clinician.
Not an exact lifespan prediction
The charts are meant to show plausible direction and reserve, not certainty about how long you will live.
Not lab-grade testing
Wearable data, field tests, and self-estimated inputs are useful, but noisier than direct clinical measurement.
Not finished science
This product will evolve as the underlying research review and calibration work improve.