Available on iPhone

Strength training that learns how you train.

Cexi reads every set, effort, and recovery day, then reshapes your next workout automatically. The training models run on your iPhone, so it adapts to you, not a template.

Download on the App Store

Free, no subscription

Cexi Home screen: a readiness score of 73, today's chest session ready to start, and the body recovery map below it.
  • On-device intelligence
  • Recovery-aware planning
  • Adaptive per lift
  • Apple Health & Watch
  • Private by design

A real app, not a concept.
Every screen below is the shipping build.

  • Cexi Home: readiness 73 above a completed session summary and the next recommended workout.

    Today

  • Cexi Workouts tab with saved Legs, Push, and Pull templates.

    Workouts

  • Cexi exercise view for Barbell Bench Press showing this week's target.

    Logging

  • Cexi Stats tab: readiness 61, Balanced, with contributing factors.

    Readiness

  • Cexi Stats tab showing weekly volume, most active day, and a consistency streak ring.

    Progress

  • Cexi plan calendar for July with completed and planned sessions colour coded by split.

    Planning

  • Cexi Coach answering with a chest session: bench press for 3 sets of 8 to 10 reps at RPE 7 to 8, then cable fly for 3 sets of 12 to 15 reps.

    Coach

The loop

One training loop.
Every session sharpens it.

  1. Plan intelligently

    Today's session is already built: the right movements, sets, and starting loads for where you are right now. Or let Cexi design a fresh workout around your equipment and recovery.

  2. Train with context

    Log weight, reps, and reps-in-reserve in seconds. Cexi shows the target it chose and why, and a Live Activity keeps your set and rest timer a glance away.

  3. Adapt from every session

    Afterwards it updates what it believes about each lift and muscle. Sleep, HRV, load, and your check-ins feed one readiness score calibrated to your own responses.

Cexi Workouts tab: start a workout now, let Cexi design one, or pick a saved template.
Cexi bench press view: last session 155 lb for 6 reps, this week target 160 lb for 6 reps.
Cexi Stats: readiness 61 with recovery, sleep, HRV, resting heart rate, load, and stress factors.
Cexi body recovery map: a front-view muscle model with per-group recovery percentages from 83 to 100 percent.

Recovery you can see.

Cexi models fatigue muscle group by muscle group, so it never sends you into a session that something is not ready for. Tap any muscle to correct the model.

The details do the work

Close-ups from the app itself: the numbers, the reasoning, and the controls you actually touch.

Readiness

One score, six honest inputs

Recovery, sleep, HRV, resting heart rate, training load, and stress each carry their own trend and label, so you can see what is helping and what is hurting.

Cexi readiness factors: recovery 61 percent moderate, sleep 6.8 hours, HRV 52 milliseconds improving, resting heart rate 56 bpm, training load 0.92 building, stress 46 moderate.

Rest

Rest timed for the lift

Each rest window is chosen for the movement and the session, and it tells you the reasoning instead of hiding it.

Cexi rest timer showing 0:22 of 2:45 remaining, with a note that a chest compound needs 2m 45s to balance recovery and session density.

Effort

Effort captured per set

An RPE scale with reps-in-reserve, logged in one tap, is what keeps progression honest rather than optimistic.

Cexi effort selector with RPE values from 6 to 10, showing RPE 7 and 3 reps in reserve selected.

Progress

Volume and consistency

Weekly volume broken down by day, your most active day, and the average per session, so a heavy week is obvious at a glance.

Cexi weekly volume chart with bars by weekday, most active day Tuesday, and average volume per workout.

Planning

Plan the month ahead

Schedule sessions in advance and see completed and planned days at a glance, colour coded by split.

Cexi planning calendar for July 2026 with days ringed by split and a legend for completed, planned, push, pull, and legs.

Watch it adapt in one session

A worked example of the loop: one hard set changes what Cexi asks for next time.

  1. Session logged

    You finish Bench Press at 4 × 6 · 185 lb. The last set is a grinder, so you tag it RIR 0.

    Bench Press · 185 lb × 6 · RIR 0

  2. Recovery evaluated

    Overnight, HRV and sleep come in low. Readiness settles at 68 and chest recovery reads 61%.

    Readiness 68 · Chest recovery 61%

  3. Next workout changed

    Instead of adding weight into fatigue, Cexi holds the load and targets a rep, protecting the progression.

    Before4 × 6 · 190 lb+5 lb
    Adapted4 × 6 · 185 lbhold load · beat 6 reps

On-device

Real models. On your device.

Cexi is not a chatbot wrapper. Its training intelligence is a set of purpose-built models that run locally and update from your data, so it keeps working offline and keeps your training private.

Progression selection
Chooses how to progress each lift, balancing proven strategies against trying something new.
Thompson-sampling bandit
Muscle recovery
Models per-muscle fatigue and recovery, calibrating recovery speed to your own responses.
Banister impulse-response
Readiness scoring
Fuses sleep, HRV, load, and check-ins, then learns which signals predict your best sessions.
Bayesian online calibration
Next-workout prediction
Learns your rotation and suggests what is next, gated by what is actually recovered.
Recency-weighted Markov chain
Energy expenditure
Turns noisy daily weigh-ins and intake into a stable TDEE estimate with a confidence range.
Kalman filter
Plateau detection
Watches performance, recovery, and programming signals to flag stalls and suggest a fix.
Multi-signal · OLS trends

Coach and workout design use secure first-party AI infrastructure over the network; the six training models above run on-device.

Everything else it does

The depth is there when you want it, without turning your training into busywork.

Training

Adaptive progression
Per-lift strategy that sharpens each session you log.
Automatic deloads
Triggered by fatigue and performance decline, not a calendar.
Log with RIR
Weight, reps, and effort captured in seconds per set.
Any split
PPL, upper/lower, full body, or a fully custom routine.

Recovery

Readiness score
One number from sleep, HRV, load, and check-ins.
Per-muscle recovery
Fatigue tracked group by group before you train it.
Apple Health & Watch
Optional sleep, HRV, and live heart-rate sync.
Daily briefing
A readable trend summary to start each day.

Insights

PRs & progress
PR wall, history charts, and a calendar heatmap.
Plateau detection
Multi-signal stall alerts with a suggested fix.
TDEE & weight trend
A stable energy estimate from noisy inputs.
Coach with context
Answers grounded in your real training data.

Privacy

Your training data is personal

Cexi is built so the intelligence lives with you, so you stay in control of what leaves your device.

On-device first

The six training models run entirely on your iPhone. Cloud sync exists only for backup and cross-device access, when you turn it on.

Clear about the coach

Your coach conversation history stays on your device. When you ask a question, only the relevant context needed to answer it is sent to our AI server.

Honest about what it is

Cexi is for general fitness and wellness with conservative guardrails. It is not a medical device and does not provide medical advice.

Read the full privacy policy · Terms

Train smarter. Recover better.
Keep improving.

Cexi is free on iPhone. Download it on the App Store and start a program that learns how you train.

Download on the App Store