Questions · answers
Frequently asked questions
Three sections: what the demo does, the physiology it rests on, and how the watch → prescription → music → watch loop actually runs. Fitness guidance only — not a medical device.
The demo
Trying it without a watch
What the live demo generates, and how close it is to a real session.
- What does the live demo actually do?
- It runs the same engine as a real session, without a watch. You set VO₂max, age and resting heart rate, pick a goal, and the engine returns a six-phase prescription — prime, ramp, load A, float, load B, restore — with the target heart-rate band and the music settings (BPM, energy, texture) for each phase. You can export it as PDF or JSON, or share it with a revocable link.
- Do I need an Apple Watch or Fitbit to try it?
- No. Without a device you enter your numbers by hand and the engine estimates the rest. Connecting Apple Health or Fitbit simply replaces those manual numbers with your measured VO₂max, resting heart rate and recent workouts.
- Is the music in the demo AI-generated?
- Yes, and it is labelled as such on every screen that plays or generates audio. Each generated track carries an inaudible watermark and an audit record so it can be attributed and registered for rights management.
- Can I choose how I want to feel instead of picking a zone?
- That is the intent of the goal presets. Rather than choosing a playlist, you choose the shape of the session — steady endurance, intervals, a calorie target or a distance target — and the engine derives the zone, BPM range, block structure and where the intensity peaks land.
The science
VO₂max, zones and why music paces effort
The formulas behind the prescription, in plain language — and the limits of what they claim.
- Why is VO₂max the number the whole product is built on?
- VO₂max is the strongest single measure of cardiorespiratory fitness, and cardiorespiratory fitness is consistently associated with long-term health outcomes in large cohort studies. It is also a number your watch already estimates, which makes it a practical input rather than a lab-only value.
- How are my heart-rate zones calculated?
- Maximum heart rate is estimated with the Tanaka formula (208 − 0.7 × age), and the five zones are derived from heart-rate reserve — the span between your resting heart rate and your estimated maximum. That is the same arithmetic a coach uses on paper, so the zones you see here line up with the zones in your training plan.
- Where does an estimated VO₂max come from if I have never done a lab test?
- Two routes. Your watch computes an estimate from outdoor walking and running: Apple Watch Series 3 and later writes VO₂max samples into HealthKit, and Fitbit exposes an equivalent Cardio Fitness Score. Alternatively, a resting-heart-rate estimate (roughly 15 × estimated maximum HR ÷ resting HR) gives a usable starting figure from two numbers you already know.
- How does music influence a workout at all?
- Music paces effort. Tempo acts as an external cue for cadence and perceived exertion, so a track whose BPM tracks your target zone makes it easier to hold that zone without watching a screen. Instead of assembling a playlist that happens to sit near the right tempo, the engine generates audio at the tempo your prescription calls for and moves it as your heart rate moves.
- Is any of this a medical device or medical advice?
- No. VO₂max.One is fitness guidance, not a diagnostic or therapeutic device, and nothing here should be used to make a clinical decision. If you have a cardiac condition, are on rate-limiting medication, or are returning to training after an event, speak to a physician before following any prescribed intensity.
How it works
Measure, generate, move, adapt
The closed loop from watch to audio, plus permissions, storage and accountability.
- What is the closed loop?
- Measure, generate, move, adapt. Your watch measures heart rate, pace and VO₂max; the fitness engine turns that into an intensity prescription; the music engine generates audio that matches it; you train, and the new biometric data from that session feeds back into the next prescription. Nothing is a fixed playlist, so every session is informed by the one before it.
- What happens in real time during a session?
- Your live heart rate is sampled continuously. Tempo tracks a cadence-locked multiple of your target band, energy scales with how far into the zone you are, and texture opens or thins out as intensity rises and falls. If you drift below the target band the music pulls forward; if you overshoot, it eases so you settle back down.
- Which metrics do you read from my watch, and can I revoke that?
- Read-only scopes: heart rate, VO₂max or Cardio Fitness Score, resting heart rate, and optionally workouts, body mass and sleep. Nothing is ever written back to Apple Health or Fitbit. The device manager shows connected status, last sync and every granted permission, and revoking there clears the metrics immediately.
- Where is my data stored?
- Session history, goals and connection state live in your browser on this device. The only thing that leaves the browser is a share link you create yourself — and you can revoke it at any time, which invalidates it for everyone who has the URL.
- How is the generated audio kept accountable?
- Every generation writes an append-only audit row that binds the physiological prescription ID, generation timestamp and audio ID, hash-chained to the row before it. Metadata is injected into the file (ID3 plus watermark) so the track can be matched by YouTube Content ID and attributed correctly downstream.
Still curious?
The fastest answer is a session.
Generate a six-phase prescription in the browser, or connect your watch first and let the numbers come from your own physiology.