Train for the body you have today.
Fit4i reads your recovery — HRV, sleep, resting heart rate — and your training history to recommend the right workout for today.
- Adaptive workouts
- Apple Health integration
- Recovery-based recommendations
- Nutrition tracking
Built for Apple Health
Reads sleep, HRV, resting heart rate and blood oxygen — with your permission, read-only.
Designed for iPhone
A native iOS app. Works with Apple Watch data via Apple Health, and with Polar devices.
Privacy-conscious
No ads, no data selling, no tracking across apps. Food photos are analysed and discarded, never stored.
Training and nutrition in one app
Workouts, recovery, calories, protein, fiber, water and body weight — one place, one plan.
How Fit4i works
Four steps from raw data to a session that makes sense today.
Connect
Link Apple Health or a Polar device. No wearable? A 10-second morning check-in works too.
Understand
Fit4i compares today's HRV, sleep, resting heart rate and blood oxygen against your personal baseline, and looks at your recent training.
Adapt
The app adjusts today's recommendation — full session, reduced volume, or a recovery day.
Train
Open Fit4i and see what makes sense for your body today — with sets, reps and working weights picked for you.
Your plan should adapt when your body does.
The same program is not the right program every day. Fit4i uses your recovery signals to help adjust today's session — so hard days land when you can handle them.
What Fit4i looks at
HRV
vs your personal baseline
Sleep
duration and quality
Resting heart rate
vs your 30-day norm
Blood oxygen
overnight SpO₂
Recent load
days trained without rest
How you feel
a quick morning check-in
Ready — Full session as planned — a good day to push.
Balanced — Session kept, volume trimmed about 25%.
Recover — An easy day — the plan backs off so you can come back stronger.
Readiness recommendations are guidance for training decisions, not a medical assessment. Recovery-based adjustments are part of Fit4i Pro; a “feeling unwell” flag always eases the day for everyone.
Workouts built around you — then rebuilt every day.
Your program comes from a training engine grounded in sports science — progressive overload, volume waves and planned deloads — not from a fixed template.
Personalised program
Built from your goal, experience level, equipment and schedule — gym, home dumbbells or bodyweight only.
Automatic progression
Weights, reps and sets advance as you get stronger — no spreadsheet required. Free for everyone.
Volume periodization
Training waves build volume week by week, with planned deloads and age-aware recovery — the way a coach would program a cycle.
Short on time?
Tell Fit4i you have 20, 30 or 45 minutes. It compresses rest and trims accessories — your main lift is never touched.
Exercise swaps
Machine taken? Swap any exercise mid-workout for an alternative that hits the same muscles.
Comeback mode
Missed a week or three? The plan restarts gently and rebuilds — no guilt, no injuries.
Works around injuries
Tell the app what hurts and it re-plans around it, swapping or removing risky lifts.
You stay in control
Edit any generated program, build your own from scratch, and swap what you don't like.
One plan, two very different mornings
High readiness
Normal or progressive session — weights move up when you've earned it.
Low readiness
Reduced volume, easier intensity, or a recovery-focused alternative.
These are the app's recommendations — you always decide what to do.
Training and nutrition in one place.
Daily calorie, protein and fiber targets tied to your goal — and they adapt as your weight trends.
Log a meal from a photo
Snap
Take a photo of your plate.
Recognise
Fit4i identifies the foods and estimates portions and macros.
Review
Check the results and correct anything that's off — nothing is logged blindly.
Done
The meal lands in your diary with calories, protein, carbs, fat and fiber.
- Water tracking with a personal daily target
- Supplement logging — whey, gainer, creatine — with proper serving math
- Body-weight trend that recalculates your calorie target
- Food database search plus a photo scan for everything else
Photo recognition produces estimates. Portions and mixed dishes can be hard to judge from a single photo, so you always review and confirm before anything is logged. Photo meal logging is part of Fit4i Pro.
See more than completed workouts.
Fit4i connects your recovery, training load, nutrition and progress — so the picture is whole, not four disconnected charts.
Workout history
Every session, every set, every weight — searchable by week, month or quarter.
Strength trends
Estimated one-rep-max progress per muscle group, with a clear percentage change.
Personal records
New PRs are detected and celebrated the moment you finish a session.
Volume and consistency
Total workouts, tonnage and sets for any period.
Body-weight trend
Log weigh-ins and watch your calorie targets adapt to the trend.
Session debriefs
After every workout: what changed, what progressed, what's next.
Not another workout logger.
Traditional workout tracker
- Records what you already did.
- Uses a mostly fixed plan.
- Leaves intensity decisions to you.
- Keeps nutrition and recovery in separate apps.
fit4i
- Helps decide what to do today.
- Adapts recommendations using recovery data.
- Keeps training, recovery and nutrition connected.
- Makes daily planning easier.
Free to train. Pro to adapt.
Every new account starts with 14 days of Pro — no card required.
Free — forever
- Build and edit your workout program
- Guided logging and full history
- Automatic weight and rep progression
- Fit a session to 20, 30 or 45 minutes
- Calorie, protein and fiber targets
- Water, body weight and supplement tracking
Pro
14 days free- Auto-generated programs from your goal and equipment
- Daily readiness from HRV, sleep and check-ins
- Recovery-driven session adjustments
- Periodized training — volume waves and planned deloads
- Calorie targets that adapt to your weight trend
- Photo meal logging
- AI coach chat
Pro is an auto-renewable subscription managed through the App Store. Cancel anytime in Settings.
Your data works for you. Nobody else.
Read-only Apple Health access
Fit4i reads sleep, HRV, resting heart rate, blood oxygen, steps and energy — only the types you approve, and it never writes anything back.
No ads, no selling, no cross-app tracking
Your health data is used to adapt your training — never for advertising, and it is never sold.
Food photos are not stored
A photo is analysed to estimate macros and then discarded. It is never saved or linked to your account.
Delete everything, anytime
Delete your account in the app (Settings → Delete account) and your profile, workouts, nutrition and health data are erased.
Frequently asked questions
What is Fit4i?
Fit4i is a personal training coach for iPhone. It builds your workout program, adapts it to your daily recovery and available time, handles progression automatically, and keeps nutrition tracking in the same app.
How does Fit4i use HRV?
Fit4i compares your heart-rate variability against your own rolling baseline — not a population average. A meaningful drop, combined with sleep and resting heart rate, lowers your readiness and the app suggests an easier session. HRV is one signal among several, never the whole story.
Do I need an Apple Watch?
No. Fit4i reads data any device writes to Apple Health — an Apple Watch works great, but so do many other trackers. Polar devices can connect directly. And with no wearable at all, a 10-second morning check-in (how you slept, how you feel) drives the same adaptive logic.
Does Fit4i work without wearable data?
Yes. The full training engine — program generation, progression, periodization, time-based adjustments — works without any wearable. Readiness then comes from your subjective check-in instead of sensor data.
Can Fit4i generate workouts for home and gym?
Yes. Programs are built around your equipment: full gym, home dumbbells, or bodyweight only. You can also toggle individual equipment on and off, and swap exercises mid-workout if something is taken.
How accurate is food recognition?
It produces good estimates for common foods, but portions and mixed dishes are genuinely hard to judge from one photo. That's why Fit4i always shows you a review screen first — you check, correct and confirm before anything reaches your diary.
Is my health data private?
Yes. Health data is read with your explicit permission, used only to adapt your training, and never sold or used for advertising. Food photos are analysed and discarded. You can delete your account and all data from inside the app.
Is Fit4i a medical app?
No. Fit4i provides general fitness guidance for healthy adults. It does not diagnose, treat or prevent any condition, and readiness scores are training guidance, not medical assessments. Consult a physician before starting any exercise program.
Can I edit generated workouts?
Yes. Every generated program is fully editable — change days, exercises, sets and reps, or build a program from scratch. Editing is free for everyone.
Which devices and integrations are supported?
Fit4i runs on iPhone and integrates with Apple Health (which covers Apple Watch and most trackers that sync to it) and Polar devices via a direct connection. More integrations are planned.
Stop guessing what today's workout should be.
Let Fit4i connect your recovery, sleep, goals and training history into one clear recommendation.