.ai
AI Training That Adapts
to Your Life
Periodized programming on your iPhone and Apple Watch — that reprograms when your schedule, equipment, or energy changes.
We'll email you a TestFlight link. No credit card. Free during beta.
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Training plans break.
SinewFit adapts.
Without SinewFit
- ✕Miss Monday's workout — your whole week is off track
- ✕Hotel gym on a work trip? Your program doesn't care
- ✕Same weights week after week — no idea when to progress
- ✕Soreness piling up but the program pushes through anyway
With SinewFit
- Miss Monday? Your plan shifts to Tue-Wed-Fri automatically
- Traveling? Get a dumbbell-only or bodyweight session for that day
- Hit 3x8 at 135? Your coach says "Add 5 lbs next session"
- Sore and fatigued? It programs a deload before you burn out
How it works
Tell us about your training
Experience level, equipment, goals, injuries, schedule
Get your first training block
AI generates a full periodized plan with coaching rationale
Train and log
Smart weight cues, set-by-set tracking, real-time progression
Adapt every week
Rate your week, give feedback, get an updated plan that builds on what you did
See it on iPhone & Apple Watch
Native iOS throughout — built for one-tap set logging on the gym floor.
Your week at a glance
Log sets in one tap
Tap the body map to swap
Rest timer in the Dynamic Island
Log from your wrist
Recovery & soreness heatmap
What you get
Intelligent programming that actually progresses you, and the flexibility to handle real-world chaos.
Real Periodized Programming
Full training blocks with mesocycle structure, progressive overload, and deload timing. Not a random workout of the day.
Adapts When Life Changes
Hotel gym? Schedule shift? Missed a day? The AI reprograms your week around what actually happened, not what was supposed to happen.
Progressive Overload Engine
Tracks every set. Calculates estimated 1RM. Knows when you're ready to go heavier and recommends the exact jump.
Fatigue-Aware Recovery
Detects overreaching from your ratings, soreness, and completion patterns. Programs deload weeks before you burn out.
Strength + Cardio Together
Pace targets from your mile time. Interval structure. Distance progression. All programmed alongside your lifts.
Built for the Gym Floor
Plate calculator, warm-up ramps, rest timer with haptics, one-tap set logging. Designed to be used mid-set, not just on the couch.
Built on the most capable AI available for complex planning and multi-constraint reasoning.
Your health data stays yours
Heart rate from your Apple Watch and the workouts we write back to Apple Health are used only to operate the app. We don't sell HealthKit data, share it for advertising, or hand it to data brokers — that's Apple's policy and ours. Privacy policy.
Why I built this
I work in professional services with unpredictable hours and regular travel. I've trained for years — run real programs, understood the science — but every plan I followed broke the moment my schedule changed.
Miss two days because of a deadline? The app doesn't care. Stuck in a hotel gym? Tough luck. Only free during nap time? Not the app's problem. Same program, same weights, same schedule that stopped working weeks ago.
So I built SinewFit. An AI coach that reprograms your week based on what actually happened — not what was supposed to happen. Whether it's work travel, childcare, a busy season, or just life — it adapts so you don't have to start over.
— Sean, Founder
support@sinewfit.aiFor anyone who wants structured training
that actually fits their life
Whether you've been lifting for years or just getting started, SinewFit builds a real program around your goals, experience, and schedule — then adapts it when things change. Strength, hypertrophy, cardio, body recomp, general fitness. Full gym, home gym, or bodyweight only.
Designed for iPhone + Apple Watch
Native logging on the wrist, real-time heart rate, and a rest timer that lives in the Dynamic Island while you train.
Apple Watch
Start a session and log every set straight from the wrist. Your phone can stay in the locker.
Heart rate & recovery
HealthKit feeds heart rate, time in zones, and yesterday's effort into tomorrow's programming.
Live Activity rest timer
Glance at the Dynamic Island for your countdown — even when Spotify or your run app is mid-track.
Apple Watch is optional. The iPhone app is the source of truth — everything works without one.
Common questions
How do I get on the beta?
Drop your email above. When the next TestFlight wave opens we'll send you Apple's invite link — install TestFlight, accept the invite, and SinewFit shows up on your phone.
Is it really free?
Yes. The whole iOS app is free during the TestFlight beta. We'll always give beta testers a heads-up before any plan or pricing changes go live.
What about Android?
Not yet. We're focused on iOS + Apple Watch first because that's where the native build is most polished. A Play Store version is on the roadmap once we're confident in the iOS experience.
Do I need an Apple Watch?
No. The iPhone app is the source of truth. The Watch is a nice-to-have for set logging on the wrist, real-time heart rate, and a workout that ties into Apple Fitness — but everything works without one.
What does SinewFit do with my health data?
Heart-rate samples from your Apple Watch and the workout summaries we write back to Apple Health are used only to operate the app — we don't sell or share HealthKit data with anyone, ever. Full details are in the privacy policy.
Can I use it on the web?
There's a web version that runs the same features today, but the experience is much rougher than iOS. We're not actively investing in it. The iOS app is what you should sign up for.
Help us build this.
TestFlight caps each beta at 10,000 testers. We're onboarding in waves so we can actually read every piece of feedback. Drop your email and we'll send an invite when the next batch opens.
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