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Frequently Asked Questions

Flux Workouts is an AI-powered iOS fitness app that generates personalised strength, hypertrophy, and powerbuilding workouts. Below are answers to common questions about the app—sourced from app behaviour, technical spec, and release notes.

1. What is Flux and who is it for?

Flux is an AI-powered iOS fitness app that generates personalised, science-backed workout plans. It's built for lifters who want smart training guidance without a personal coach. The app:

• Generates workouts based on your goals, equipment, energy, and recovery
• Tracks progression with evidence-based methods (e.g. double progression, linear progression)
• Adapts over time using your history and preferences
• Manages fatigue and recovery
• Can sync with Apple Health (sleep, HRV, heart rate) when you enable it

You choose your training goal (Strength, Hypertrophy, or Powerbuilding), how many days per week you train, and your gym's equipment; Flux suggests and adjusts workouts accordingly.

2. What's the difference between the Free and Pro tiers?

Free tier includes:

• Basic workout generation
• Progression tracking
• Workout history
• Simple readiness (subjective recovery only)
• Local data storage

Pro tier adds:

• ML-powered exercise selection (enjoyment and performance predictions)
• Plateau interventions (e.g. Joker Sets, Drop Sets, goal shifts)
• Advanced recovery (muscle + systemic + sleep, and HRV/RHR when HealthKit is on)
• Training strategy periodisation (e.g. volume accumulation, intensity peaking, deload)
• Superset recommendations
• Weekly Check-In reports and coaching directives
• Cloud sync and backup
• Pro app icon

ML features (enjoyment/performance predictions, advanced recommendations) also require calibration to be complete so the app has enough data to personalise.

3. How does workout generation work? Why this focus/duration/energy?

When you tap Generate (or use the suggested config), the app:

1. Uses your selected or default gym to filter exercises by equipment.
2. Picks a focus (split) — e.g. Push, Pull, Legs, Upper, Lower, Full Body — by rotation and, for Pro users, any Weekly Check-In directive.
3. Assesses readiness from your subjective recovery score, fatigue state, per-muscle recovery, and (if Pro + HealthKit) sleep, HRV, and resting heart rate.
4. Selects exercises (compound then accessories) using your preferences, equipment, and Pro ML when calibrated.
5. Sets sets, reps, weight, rest, and RIR from your goal, experience, and progression history.
6. Optionally groups exercises into supersets (Pro).
7. Checks duration against your time budget and trims if needed.

So the suggested focus, duration, and energy come from: your profile, last sessions, recovery, and (for Pro) check-in directives. You can still change focus, duration, and energy on the config screen before generating.

4. What is "calibration" and when does it end?

Calibration is the initial learning phase where the app collects enough workout data to personalise recommendations. During calibration:

• The app uses a balanced strategy and doesn't yet use full ML exercise selection or strategy periodisation.
• Weekly Check-In reports are generated, but coaching directives are not (insufficient data).
• Calibration is considered complete once the app has collected enough workout data (the app will show progress in the meantime).

Once calibration is complete, Pro features like ML exercise selection and check-in directives can fully activate.

5. What is "readiness" and what affects it?

Readiness is a score that influences how much volume and intensity the app prescribes. It's built from:

• Subjective: The recovery slider (1–10) you set when configuring a workout.
• Systemic fatigue: Your recent training volume and fatigue.
• Per-muscle recovery: How recently each muscle was trained and how much load it had.
• Sleep: Quality/duration (and HealthKit sleep when enabled).
• HRV and RHR (Pro + Apple Health): Heart rate variability and resting heart rate improve the score when available.

Low readiness reduces suggested volume (e.g. fewer sets, higher RIR, longer rest) and can suggest a recovery or deload session instead of a full-intensity workout. The app never forces you; you can still change energy and focus and generate.

6. How does Apple Health (HealthKit) integration work?

If you turn on Apple Health Sync in Profile → App Settings:

• The app can read: sleep, resting heart rate, heart rate variability (HRV), VO2 Max, date of birth, and biological sex.
• The app can write: workout sessions (Functional Strength Training) and active energy burned.

Readiness uses sleep, HRV, and RHR when available (Pro + HealthKit) to refine recovery. Weekly Check-In (Pro) can use historical sleep/HRV/RHR for trend and correlation-style insights. You can disable Health Sync anytime in Profile.

7. How does progression work? What are "double" and "linear" progression?

• Double progression (default): You first build reps within a range (e.g. 8–12) at a given weight. When you hit the top of the range consistently, the app suggests adding weight.
• Linear progression: When you hit your target reps (and RIR), the app suggests adding weight next time.

Targets and step sizes come from your goal (Strength / Hypertrophy / Powerbuilding), experience level, and gym increments. If you significantly change weight during a workout, the app may prompt: "Use X kg next time?" — accepting updates the baseline for future prescriptions.

8. What is RIR (Reps in Reserve) and why does the app ask for it?

RIR is how many reps you felt you had left in the tank (e.g. 2 RIR = could have done 2 more). The app uses it to:

• Calibrate how hard you're actually working.
• Decide progression (e.g. add weight vs retry same prescription).
• Improve future targets and readiness.

You're asked to enter RIR (or RPE) after sets where it matters. The app uses this to learn your effort accuracy over time.

9. What is the Weekly Check-In and is it only for Pro?

Weekly Check-In is a Pro feature. You choose a check-in day (default Monday) in Profile → Weekly Check-In. On that day, a report is generated that includes:

• Last week: Sessions completed vs planned, volume/sets, enjoyment, PRs, adherence.
• Health & recovery (if HealthKit is on): Sleep, HRV, RHR trends and correlation-style insights.
• This week: Current phase, what to focus on, session expectations.
• Coaching actions (when applicable): e.g. "Prioritise Lower Body", "Lighter intensity this week".

Those coaching directives can influence the suggested focus and energy on the Dashboard. You can always change focus and energy on the config screen, or turn off Weekly Check-In in Profile.

Free users see a locked toggle with a "Pro Feature" message.

10. If I reinstall the app or get a new device, do I lose my data?

If you're signed in and have used cloud sync (Pro):

• Synced to the cloud: Profile, fatigue state, muscle fatigue, calibration state, workout history, exercise preferences, gyms, and check-in reports. After reinstall, the app restores these from the cloud.
• After restore: The app may relearn things like pacing and duration from your history.
• Local-only state: A few settings may reset and will adapt again as you use the app.

With Pro and sync, your important data comes back after reinstall.

11. Why does the app suggest a different gym or focus than I want?

The suggested gym and focus come from:

• Your default gym and last used gym.
• Split rotation (e.g. Push → Pull → Legs).
• Volume balance (e.g. if you've missed "Lower Body" often, the suggestion may prioritise it).
• For Pro: Weekly Check-In directives.

This is only a suggestion. Before generating, you can change gym, focus, duration, and energy on the config screen.

12. I keep removing or swapping the same exercise. Does the app remember?

Yes. If you remove an exercise from a workout multiple times, the app treats it as a dislike and deprioritises it in future generation. Swapping an exercise is also recorded and used to prefer the exercise you chose instead.

13. Why is the estimated workout duration different from how long I actually take?

The estimate uses:

• Exercise count, sets, reps, rest, and warmups.
• Your experience level.
• Learned behaviour per gym: over time the app learns how your actual session length compares to its estimate and adjusts future estimates.

Early estimates can be off. They improve as you log completed sessions.

14. What are supersets and when do I get them?

Supersets are two or more exercises performed back-to-back with minimal rest. Flux (Pro) can recommend superset pairings that:

• Don't overlap muscle groups (e.g. pairing a push with a pull).
• Have similar set counts and sensible rest.

Superset suggestions appear in the workout preview and in the active workout flow. You can still edit or ungroup exercises.

15. How do I get support or send feedback?

Use the in-app Contact option or email [email protected]. For privacy and data handling, refer to the app's privacy policy and terms.

Quick reference

Topic	Where to look in the app
Goals & frequency	Profile → My Details
Gyms & equipment	Profile → Gyms
Pro / subscription	Profile → Flux Pro, paywall
Weekly Check-In	Profile → Weekly Check-In (Pro)
Apple Health	Profile → App Settings → Apple Health Sync
Progression type	Profile → Progression (Double vs Linear)
Focus / energy	Workout config screen before generating

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