Help and product guidance

Frequently asked
questions.

Flux Workouts is an adaptive workout planner for iPhone and iPad that uses on-device machine learning to generate personalised strength, hypertrophy, and powerbuilding workouts. Below are answers to common questions—sourced from app behaviour, technical spec, and release notes.

1. What is Flux and who is it for?

Flux Workouts is an iOS adaptive workout planner that generates personalised, science-backed workout plans using on-device machine learning—not chatbots or cloud AI agents. 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. How do the free trial and Lifetime Unlock work?

Flux is free to download with a 14-day app-managed Full Access trial. It requires no payment, starts no subscription and never charges you automatically. During the trial, every feature is available:

• Workout generation, progression tracking, history, and routines
• 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)
• Five strength periodisation models with model-aware workout targets
• Superset recommendations
• Weekly Check-In reports and coaching directives
• Cloud sync and backup

After the trial expires, training features require a one-time Lifetime Unlock or an eligible existing entitlement; there is no ongoing free training tier. Lifetime Unlock is a single non-consumable in-app purchase for permanent Full Access, not a subscription. Apple shows the price for your storefront before you confirm. Purchase and restore remain available after the trial.

Eligible existing paid owners and recognised historical purchasers retain permanent Full Access. Lifetime and Founder Lifetime holders do not need to buy again. Use Restore Purchases with the same Apple Account if your purchase is not recognised.

ML features still require calibration so the app has enough data to personalise. Reinstalling the app does not restart the trial.

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 any Weekly Check-In directive.
3. Assesses readiness from your subjective recovery score, fatigue state, per-muscle recovery, and (with HealthKit enabled) sleep, HRV, and resting heart rate.
4. Selects exercises (compound then accessories) using your preferences, equipment, and ML when calibrated.
5. Sets sets, reps, weight, rest, and RIR from your goal, experience, and progression history.
6. Optionally groups exercises into supersets.
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 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:

• ML personalisation needs enough completed-workout data; your goals and settings still guide the workout prescription.
• 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, 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 (with 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?

Apple Health is optional. You can use Flux without sharing Health data. If you explicitly request access through onboarding or Apple Health Sync in Profile → App Settings, you choose which data to share. With the relevant permissions and available data:

• The app can read data such as 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 through HealthKit to refine recovery. Weekly Check-In can use historical sleep/HRV/RHR for trend and correlation-style insights. The onboarding Reviewed label means the permission request finished—not that every permission was granted. Normal Health Insights refreshes do not start another permission request.

You can disable Health Sync anytime in Profile. This controls sync within Flux; it does not change your system permissions, which you can manage in the Health app.

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.

These load-progression methods are separate from your routine’s periodisation model, including the Linear model.

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. Is the Weekly Check-In included?

Weekly Check-In is included with Full Access during the trial and with Lifetime Unlock or eligible existing access. 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.

There is no separate Weekly Check-In purchase.

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:

• Included in cloud backup: Profile, fatigue state, muscle fatigue, calibration state, workout history, exercise preferences, gyms, and check-in reports. Sign in to the same Flux account to restore data that successfully synced.
• 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.

A workout saved only on your device has not necessarily reached the cloud, especially if you finished offline. Confirm that your data has been backed up before deleting or reinstalling the app; unsynced local data cannot be restored from a cloud backup. Reinstalling does not restart the trial. See offline workout saving.

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).
• 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 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 does Flux handle privacy and on-device machine learning?

Flux is not a ChatGPT-style fitness chatbot. Personalisation uses on-device machine learning trained on your logged workouts, preferences, and recovery signals.

• On-device ML: Exercise selection, progression, and readiness models run on your iPhone or iPad.
• Optional cloud sync: Signed-in users can back up profile, history, and preferences. Workout data is not sold.
• Optional Apple Health: HealthKit sync is user-controlled and can be disabled anytime in Profile.
• Security: Flux adapts from training data you log—not from open-ended AI chat prompts.

See the full privacy policy for data handling details.

16. 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.

17. Which strength periodisation models can I choose?

When generating a strength routine, choose one of five models:

• Adaptive Block: phases shaped by your goals, experience, completed training and recovery.
• Daily Undulating (DUP): Heavy and Volume work across your strength routine, with Moderate sessions where appropriate.
• Linear: a structured six-week path from Volume through Build and Heavy work to Deload.
• Weekly Undulating (WUP): planned waves of Volume, Moderate and Heavy training, followed by recovery.
• Manual: choose an eligible training phase and hold it until you change it, apart from temporary safety recovery.

The model shapes sets, reps, load, rest and effort targets. Managed progression follows completed training rather than elapsed calendar days, with safety deloads when recovery needs attention.

Your routine keeps its model; generate a new routine to change models. Routine Library programmes keep their authored progression, HIIT keeps its timed prescription, and adaptive workout adjustments remain a separate control.

18. Can I finish a workout without an internet connection?

Yes. In Flux 8.5.1, the workout completion screen confirms after your workout and final feedback save successfully on your device. It does not wait for cloud acknowledgement, so losing Wi-Fi does not keep the completion tick spinning after that local save.

If the local save itself fails, Flux explains the problem and offers a retry without repeating completion processing. Signed-in cloud backup can sync later when the app has connectivity. This is not a guarantee of immediate upload while the app is closed or suspended, and local storage is not a replacement for a completed cloud backup.

Internet-dependent services still need connectivity. See the Flux 8.5.1 release highlights for more about the completion improvements.

19. What changed in Routine Details?

Overview brings your workouts and progress together. Settings groups the controls available for that routine. Saved programmes with an available template also have a Guide for their instructions; not every routine has a Guide.

Clearer phase and cycle displays help you see your training position. Planned muscle-volume views reflect the Routine Library phase you are viewing, and Exercise Details can load older completed-workout records as you browse your history.

Quick reference

Topic	Where to look in the app
Goals & frequency	Profile → My Details
Gyms & equipment	Profile → Gyms
Feature access	Profile → Flux Full Access: trial, Lifetime and restore
Periodisation model	Choose when generating a strength routine
Routine controls	Routine Details → Overview / Settings / Guide where available
Weekly Check-In	Profile → Weekly Check-In
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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