Coming to iOS · TestFlight first
The training notebook
that fits your practice.
Lift, practice yoga, take barre, build an aerobic base, or mix the week. Flexbound keeps every raw word, builds around your movement styles and equipment, and runs the numbers with published, citable methodology. The plan and the math never come from an AI guess.
Built on 25+ peer-reviewed sources · every number traceable to its rule
44
versioned methodology rules, each tied to sources
25+
peer-reviewed papers & position stands cited
0
numbers invented by AI. The calculators decide.
100%
of your raw notes preserved, forever unedited
The product
Paper feel. Engineering underneath.
No dashboards, no neon, no streak confetti. A leather-and-cream notebook with a coach in the margins and honest math in the spine.
Movement styles
Start with how you actually like to move.
Choose lifting, yoga, Pilates, barre, HIIT, steady cardio, or a mix. Flexbound builds a recoverable week from those choices instead of treating every non-lifting session as an afterthought.
- Guided sessions matched to level, duration, and goal
- Cardio-only weeks become a real Aerobic Base plan
- Mixed weeks respect lifting days and recovery capacity
The journal
Write freely. Parse when you're ready.
Bench 225 × 5. Eggs and rice. Felt strong. Your words stay the source of truth. Tap Parse and Flexbound structures the page into sets, meals, and bodyweight without changing a single character you wrote.
- Raw journal text is never rewritten
- Ambiguous lines ask before guessing
- Deterministic parser first; AI assists only when needed
Nutrition
Estimates with sources, never fake precision.
Mark how complete the day is, write what you ate, and let Pro estimate macros through USDA and Open Food Facts first. Every estimate shows its source, its serving assumption, and its confidence.
- Complete days teach your real maintenance; partial days never skew it
- Source, serving assumption, and confidence on every number
- Your corrections become truth for next time
Progression
A coach in the margins, not a chatbot.
Double progression, smallest-increment loading, deload signals, and pain flags are computed from your confirmed history by versioned rules. A quiet margin note explains the result and cites the methodology.
- Every recommendation cites its rule and evidence level
- Attendance as tally marks, with no badges or confetti
- Recommendations never overwrite your plan without confirmation
Movement index
Every lift has a page in the book.
Browse movements like a handwritten catalog, then open a lift's page for best set, estimated 1RM, trend, and exactly what to do next session. The formula is documented, not hidden.
- Estimated 1RM via the documented Epley formula
- Best sets and trends from confirmed history only
- Next-session targets you can trace to a rule
The planner
Plans built for your movement, your gear, your hour.
Tell Flexbound how you like to train, where you do it, what you own, and how long a session really gets. The plan respects each answer as a hard constraint, and every structural choice cites the rule that made it.
Style-aware
Yoga, barre, cardio, or iron
Each practice gets its own scheduling logic, evidence, progression, and honest limits. Mixed weeks are capped so preference does not become overbooking.
Time-aware
A 30-minute plan is not a rushed 60
Session length is a budget, not a suggestion. Accessories trim first, rest scales second, and the day's priority compounds are protected to the end.
Equipment-aware
No cable machines in a dumbbell plan
Home, full gym, or no equipment: the planner only selects what you can perform and says so when a movement pattern is honestly unavailable.
The difference
AI in the margins. Never in the math.
Most fitness apps now let a language model guess your numbers. Flexbound draws a hard architectural line and publishes it.
The calculators decide
- Calories, macros & adaptive TDEE
- Estimated 1RM, volume & progression
- Deload thresholds & pain responses
- Workout plan structure & goal pacing
Versioned rules · cited sources · audit trail
The AI may only
- Rephrase a finished weekly review
- Explain a plan without changing it
- Draft a parse for ambiguous notes that you confirm
- Summarize research for human review
If AI prose invents a number, it's discarded
Built like a logbook
For people who already think in notebooks.
The app feels like leather and cream paper because that's the product: a durable training log you'll still trust in ten years, with intelligence that stays in the margins.
- User truth
- What you wrote, edited, and corrected. It is never mutated.
- Nutrition truth
- Source-backed estimates you can always override.
- Methodology truth
- Versioned training rules stored as data, never prompt text.
How it works
Three moves. That's the loop.
- 01
Write the session
Training, food, bodyweight, and how it felt, all in your own words.
- 02
Confirm the structure
Review the parsed table. Edit anything. Then it becomes history.
- 03
Read the margin
Next-session targets, weekly review, and goal pacing, explained and cited.
Questions
Fair questions, straight answers.
What is Flexbound?
Flexbound is a workout notebook app for iOS. You write training and food notes in your own words; the app parses them into structured sets, meals, and bodyweight data without ever rewriting your raw entry. Deterministic math handles progression, macros, and TDEE. AI only writes and explains.
Does AI calculate my calories or training numbers?
No. Calories, macros, TDEE, estimated 1RM, volume, and progression all come from versioned deterministic calculators grounded in peer-reviewed research. AI is architecturally forbidden from producing numbers; it can only rephrase and explain results the math already produced.
Is Flexbound free?
The core notebook is free forever: unlimited raw journaling, deterministic workout parsing, food notes, backup and sync. Flexbound Pro adds sourced calorie and macro estimates, weekly reviews, workout plans, and unlimited history.
Can I use Flexbound if I train at home?
Yes. You declare where you train and exactly what you own: dumbbells, kettlebell, bands, a secure band anchor, a pull-up bar, a bench or box, or nothing at all. Plans are built only from movements your equipment can perform, and if a pattern like vertical pulling is not honestly trainable with your setup, the plan says so instead of substituting something that does not do the same job.
Do I have to be a lifter to use Flexbound?
No. Choose lifting, yoga, Pilates, barre, HIIT, steady cardio, or any recoverable combination. Guided styles use curated sessions matched to your level and time; cardio-only users receive an Aerobic Base Week; lifting plans use deterministic resistance-training rules. The app states honestly when a selected style does not provide progressive resistance.
When does Flexbound launch?
Flexbound is coming to iOS, opening on TestFlight first. Email us to join the early-access list and get one email when it opens.
Coming to iOS
Be first when Flexbound ships.
Flexbound is coming to iOS, TestFlight first. One email when it opens. Nothing else.