Skulpo

How the model works

How Skulpo turns logged sets into recovery states: muscle mapping, the recovery model, training timing, age and sex, and the research behind it.

How it works

  1. You log the set.

    Weight and reps on steppers, previous values pre-filled. Copy your previous workout in one tap.

  2. Skulpo maps it to muscles.

    690 exercises with primary and secondary muscle roles. Your own exercises get the same mapping.

  3. The recovery model updates.

    Each muscle carries a fatigue estimate that decays over time, scaled to the age in your profile. Cardio counts too — cycling, swimming, rowing, hiking.

  4. You see what's ready.

    The body map, a per-muscle timeline and the state's explanation. It's an estimate from your log — not a measurement of your body.

The difference

Your history becomes a body map of readiness.

Every set you log is mapped to the muscles it trains. Skulpo runs that history through a recovery model and shows the result on a body map: each muscle in one of seven states, from Overloaded to Peak. The state is a label, not just a colour — and you can tap any muscle to see why.

MUSCLE STATES

Overloaded
High fatigue — rest day recommended
Recovering
Still recovering — light volume only
Ready
Recovered enough — small residual fatigue may remain. A slightly different green right after Recovering means a bit more fatigue is left.
Peak
Best time to train, by Skulpo's model
Past peak
After Peak — fully recovered, a good time to train
Active workout
Currently training — within 90 min of last set
Untrained / Detrained
Never trained yet — or trained but adaptation faded after a long break (over a week)
Saturday, June 27, evening — states from the same training log as the body map at the top of the page

Readiness

Tap a muscle. See its whole recovery.

Each muscle has its own screen: the current state, a timeline of its recovery curve with the Ready line and the Peak state, and a “Why” breakdown — the age modifier from your profile and what hit this muscle in the last 7 days.

Skulpo muscle screen: current state, recovery percentage, top exercise and the exercise list Skulpo muscle screen: current state, recovery percentage, top exercise and the exercise list
Skulpo muscle screen: recovery timeline with the Ready line and the Peak state Skulpo muscle screen: recovery timeline with the Ready line and the Peak state
Recovery timeline

The science

Why timing matters

Every workout damages muscle fibers. Performance drops below baseline (the DIP).

In the days after training, your body repairs and can strengthen the muscle above its previous level. This is SUPERCOMPENSATION — performance rising above where it started.

Train while the muscle is still Overloaded or Recovering = no supercompensation. The dip stacks deeper with each session and performance slides instead of rising. This is OVERTRAINING.

Skulpo estimates your Peak from your training history — when the curve turns blue, it's the best time to train.

Supercompensation: performance after a training stimulus, and what happens when the next one comes at the Peak or too soonperformancetrainingstimulusbest moment to apply thenext training stimulussupercompensationsupercompensationtimerecoveryrecoveryimproved performanceovertrainingtraining stimulusapplied too soon
Schematic, not your data. Gray curve = performance after a workout. Blue = next stimulus at the Peak → performance builds up. Red = stimulus too soon → overtraining.
Supercompensation: performance after a training stimulus, and what happens when the next one comes at the Peak or too soonperformancetrainingstimulusbest moment to apply thenext training stimulussupercompensationsupercompensationtimerecoveryrecoveryimproved performanceovertrainingtraining stimulusapplied too soon

Schematic, not your data. Gray curve = performance after a workout. Blue = next stimulus at the Peak → performance builds up. Red = stimulus too soon → overtraining.

What that looks like for real exercises

One hard session — four sets close to failure — logged for a 25-29-year-old man with no other training. Times come from Skulpo's own recovery model; your profile and your history will move them.

Bench Press

Main muscles: Chest

Chest

Peak opens 92 h Peak closes 128 h

hours after the session

Squat

Main muscles: Quads

Quads

Peak opens 132 h Peak closes 180 h

hours after the session

Barbell Curl

Main muscles: Biceps

Biceps

Peak opens 66 h Peak closes 90 h

hours after the session

Deadlift

Main muscles: Back, Glutes, Hamstrings

Back

Peak opens 105 h Peak closes 153 h

Glutes

Peak opens 118 h Peak closes 166 h

Hamstrings

Peak opens 144 h Peak closes 192 h

hours after the session

These are baseline values for a 25–29-year-old male trainee. The app scales the window to your age and sex — experience changes how hard a session hits you, not how long the peak lasts. Older trainees get longer peak windows, younger ones shorter.

The direction of these effects — a dip, a rebound, and a cost to training too soon — is well supported in the literature. Exact timings are not: Skulpo's windows are an evidence-informed design choice, not a measured biological constant. Sources: Literature.

Computed with the app's recovery engine.

Scaled to your age and sex.

Skulpo scales each muscle's recovery — and how long its Peak lasts — to the age and sex in your profile. The “Why” screen shows the modifiers applied to you. They are model estimates informed by published research — see Literature — not a measurement of your body and not a diagnosis.

Skulpo “Why” screen: recovery breakdown with the age modifier for a test profile Skulpo “Why” screen: recovery breakdown with the age modifier for a test profile

Literature

The full list of studies used in the recovery model, grouped by topic.

Open the literature list