Where the exercise data comes from
The base catalogue of 873 exercises derives from wrkout/exercises.json, an open dataset released into the public domain. It supplies the exercise names, instruction steps, demonstration images, and the muscle, equipment, difficulty and mechanic labels.
That dataset is widely republished, and a verbatim copy of it would be worth nothing to you. What follows is what we add.
What we compute on top
Equipment normalisation
The source leaves the equipment field null for 77 bodyweight and stretching movements. We verified every null row and reclassified them as requiring no equipment, which is why our bodyweight count (188) is higher than a raw read of the dataset gives. We also repair mis-encoded characters in the instruction text.
Equipment swaps
For each exercise we rank every other exercise that shares a primary muscle but uses different equipment, scoring on weighted muscle overlap (primary-to-primary counts fully, shared secondaries a quarter), matching force and mechanic, and how accessible the equipment is. We gate swaps to the same category, so a strength movement never suggests a plyometric one just because the muscle label matches.
Difficulty progressions
Easier and harder variants are drawn from exercises sharing both the primary muscle and the force pattern, then ordered by the dataset's difficulty rating.
Superset pairings
Superset partners use an explicit antagonist map — chest against back, quads against hamstrings, biceps against triceps, abs against lower back — rather than simply inverting the push/pull label. The dataset classifies a barbell squat as a "push", so a naive inversion pairs squats with barbell rows. Ours pairs them with Romanian deadlifts.
Limitations, stated plainly
- Difficulty ratings are the source dataset's, not a clinical assessment.
- Muscle attributions are anatomical labels, not EMG-verified activation data.
- Derived relationships are computed from these labels. They are a good starting point for choosing a substitute, not a substitute for coaching.
- Nothing here is medical advice. If something hurts, stop and ask a professional.
Corrections
If you spot an error in an exercise description or a relationship that makes no sense to a coach, email support@genfit.fit and we will fix it. Accuracy complaints get priority over everything else.
The app
Genfit App is available on iOS and the web. Workout generation and tracking are free; nutrition logging and macro targets are the paid tier.