Hypertrophy tracker · Paid app, free trial · iOS and Android

Track the stimulus.
Not just the sets.

Your logbook counts sets. Stimuli measures the stimulus behind them. Every muscle gets an Effective Work score as you log sets, and the figure shows which muscles got a growth signal this week and which have recovered for the next.

Download on the App Store Get it on Google Play

299Exercises, calibrated
0.5RIR step
18Muscles scored weekly
Stimuli week view showing 30,201 weekly Effective Work and a per-muscle stimulus heatmap on front and back anatomy figures
The method

Two lifters do 20 sets of chest. One grows.

The tracker can tell you which. Set counts treat every set the same. RIR 3 and RIR 0 are not the same set, a partial is not a full range rep, and an incline press is not a fly. Stimuli scores the difference.

Volume

A set is shared across the muscles that did the work. A bench set is a full set for your chest and a fraction for your triceps.

Proximity to failure

Reps near failure count. 60 × 15 at RIR 6 scores zero. It felt like work. It was not stimulus.

Recovery

Each muscle recovers from its own last session. The figure shows where every one of them sits today.

  1. Log the set

    Load, reps, and RIR in half steps. Partials are marked. Bodyweight work starts at your bodyweight, so the math stays honest.

    Angled leg press · set 1Logged
    LOAD 195 kg · REPS 10 · RIR 1
    PREVIOUS 190 × 10 @ 1
    655Effective work

  2. Score the stimulus

    Each set is scored by per-exercise muscle coefficients, proximity to failure, and range of motion. The result is one number per set: Effective Work.

    ● Set scoredBench press
    100 × 8 @ RIR 1626EW
    60 × 15 @ RIR 60EW

    Only reps close to failure count. Easy sets score zero.

  3. Watch it land

    Effective Work rolls up per muscle, per week, against your targets. The figure shows what got stimulated and what has recovered. Sets that did not create stimulus do not count.

    Week 26Weekly effective work
    30,201▲ 2.4% vs last
    85 SETS · 4/7 SESSIONS · 13/16 MUSCLES IN ZONE
The set

Half-step RIR. Partial credit.

RIR in half steps. Partials counted at partial credit. PRs detected the moment you log the set, per exercise and per machine. Every set updates an estimated 1RM, and the next set is suggested from it.

● Next setSuggested
195 kg × 8 @ RIR 1
E1RM 267 kg  ·  LAST 195 × 10 @ 0
Stimuli session view on the cream theme: Angled Leg Press sets logged as 195 by 10 at RIR 1 and RIR 0, scored 655 and 674 Effective Work, with a suggested next set
The instrument

Reads like a gauge. Not a diary.

  • 01 · The week

    Stimulus and recovery, on the figure.

    The anatomy figure shows how stimulated and how recovered each muscle is, computed from your actual sets. Not how strong you are, and not a sleep score.

    Stimuli week view in recovery mode: quads and chest shown cooked on the anatomy figure, with the daily recovery bars and the cooked-to-fresh scale
  • 02 · The trend

    e1RM trends, with a rule.

    Every set updates an estimated 1RM, and the trend drives the next-set suggestions. PRs are detected the moment you log the set, per exercise and per machine, because stack numbers differ per machine.

    Suggestions
    The trailing e1RM trend sets the next set, not last session's numbers alone.
    The deload rule
    A plateau is not a trigger. Two weeks of falling e1RM is.
    Stimuli progress view with a bench press estimated 1RM of 116 kilograms, up 13 kilograms, and a rising e1RM trend chart
  • 03 · The program

    Tell it what you want to grow.

    Tap the muscles you are prioritizing and Stimuli builds a complete program around them, in about 30 seconds. Edit anything by hand. Manual and generated programs live in the same library, drawing on 299 exercises with video and written cues. Recent clips play offline.

    Muscle priorities inFull program out
    ~30 sGenerated, then yours to edit
    299 EXERCISES  ·  VIDEO AND WRITTEN CUES
  • 04 · The coaching

    Sunday, in writing.

    At the end of each training week, Stimuli reads it and writes back: one to three short, specific notes on what the data shows, from a muscle that missed its target to a lift whose e1RM has slid two weeks running. Observations, not edits. Program changes are proposed separately from the notes, up to five a week, and each one is yours to keep or skip. A daily check-in asks how each trained muscle feels, and your answer moves the figure.

    Daily
    Recovery check-inConfirm or correct the model, per muscle.
    End of week
    Written insightOne to three notes on the week you trained.
    Weekly
    Revision proposalsUp to five changes. Keep or skip each.
  • 05 · Recoverable volume

    How much you can take.

    Stimuli estimates the most sets, and the most Effective Work, each muscle can recover from in a week, then draws it over what you actually did. The floor is the least that grows muscle. Both lines come from your own history and move as it does, and the By muscle page ranks the ten major movers by how close each sits to its limit, with the eight indirect muscles listed below.

    Read the guide: Recoverable Volume

    Recoverable volumeThis week
    37.8kMREW · you're at 83%
    MRS 173.3 SETS
    By muscleOf its own limit
    Quads85%
    Hamstrings76%
    Lats58%
    Glutes51%
Pricing

More than a logbook. Less than a coaching app.

Stimuli costs more than a set counter. It also does more: every muscle scored for stimulus and tracked for recovery, a written read of each week, a program revised from your own data. That is the work you pay a coach for. It is priced well under an AI coaching app, and nowhere near a coach.

Logbooks
$3 to $5 / month

Count sets. Every set weighs the same.

Stimuli
$9.99 / month

Scores every set. Stimulus and recovery per muscle. A written insight every week. Revisions weekly. $6.67 a month billed yearly.

AI coaching apps
$30 to $35 / month

Priced as a service.

Logbook and coaching-app figures are monthly, from the US App Store and vendor pricing pages, checked September 2026. Prices vary by region.

Everything included
Per set
Effective Work, scored as you log it.
Per muscle
Stimulus and recovery, per week, on the figure. A daily check-in.
Per lift
e1RM trends. PRs per exercise and per machine.
Programs
Generated from your muscle priorities in about 30 seconds, or built by hand.
Every week
A written read of the week, and proposed revisions.
Library
299 exercises with video and written cues.
Your data
CSV export, kg or lb, account deletion in the app.
Stimuli Pro
$79.99/ year

$6.67 / month · billed yearly

Or $9.99 month to month.

  • Free trial for new subscribers
  • Everything included. One tier, no add-ons
  • Cancel anytime through the App Store or Google Play

Paid app. No free tier. The trial is the free part. If it does not earn a place in your training, cancel and take your data with you.

Download on the App Store Get it on Google Play

Prices in USD · Billed through the App Store or Google Play

Specification Live build · iOS and Android
e1RM window90 dtrailing, drives next-set suggestions
PR detectionper machineand per lift, the moment the set is logged
Recovery check-indailyconfirm or correct the model, per muscle
Program build~30 sfrom the muscles you prioritize
Written insightweekly1 to 3 notes on the week you trained
ExportCSVload, reps, RIR, ROM, machine
Unitskg · lblogged in the unit your gym uses
Analyticsanonymousno ad pixels, ever
FAQ

Straight answers

Q01What is Effective Work?

A per-set score of muscle-growth stimulus. Each set is scored using load, per-exercise muscle coefficients, proximity to failure, and range of motion, then rolled up per muscle, per week. It is the number your training volume was always trying to be.

Q02Can I see the math?

Yes. A set's Effective Work is the exercise's per-muscle coefficients scaled by your load relative to your estimated 1RM, by how close you took the set to failure in half-RIR steps, and by range of motion, with partials counted at partial credit. The same math runs on every set, and your CSV export carries every input you logged: load, reps, RIR, range of motion and machine.

Q03Is Stimuli free?

No. Stimuli is a paid app with a free trial for new subscribers. Stimuli Pro is $9.99 a month or $79.99 a year in USD, billed through the App Store or Google Play. The price filters for people who train seriously, and it keeps ads and data-selling permanently off the table.

Q04Is Stimuli on Android?

Yes. Stimuli is on Google Play for Android and on the App Store for iOS, with a free trial for new subscribers on both. One account works on either phone.

Q05How do I cancel?

Through your Apple ID or Google Play subscription settings, at any time. The store handles the billing, so cancelling there is the whole process. Access runs to the end of the period you have paid for.

Q06What happens to my data if I cancel?

It stays. After the subscription ends you can still open Stimuli, read your history and export it to CSV. Logging new sessions and generating programs need an active subscription. Deleting the account, and everything with it, is done in Settings.

Q07Is my data locked in?

No. Your full set history exports to CSV in one tap, including load, reps, RIR, range of motion, and machine. Account deletion lives inside the app.

Q08Does it work offline?

Logging does. Sets are stored on the device and sync when you are back online. Exercise videos you have opened recently play offline too.

Q09Does Stimuli track me?

No ad pixels, ever. The app and this site use anonymous product analytics that are not tied to your name, email, or account, and your training data is never used for advertising.

Guides

The thinking, written down.

On the App Store and Google Play

Train with intent.

Free trial for new subscribers. Your first set scores tonight.

Download on the App Store Get it on Google Play

Paid app · Free trial · iOS and Android