PlainExercise publishes a structured reference page for every exercise, muscle group, and equipment type in its dataset — built from open-licensed public exercise data. This page explains how those pages are produced, what standards they are held to, and how to report anything that looks wrong so we can fix it at the source.

How these pages are produced

Every exercise record, muscle target, equipment tag, force type, mechanic, and level on PlainExercise originates in an open-licensed dataset. We load the raw data through a documented, version-controlled pipeline and render it into exercise, muscle, equipment, variation, and workout pages using shared templates. No page is hand-written, and no count or attribute is typed in by an editor — each figure is read directly from the source record at build time and is traceable back to its row.

Editorial judgment governs the parts a pipeline cannot decide on its own: which datasets to use, how each field is defined and labeled, what the methodology says, how derived measures (such as a muscle-coverage ranking or a compound-versus-isolation share) are computed, which guides we write, and what we will not publish. The pipeline then applies those decisions uniformly across every exercise, so the rule that governs one page governs all of them. Narrative framing — common mistakes, safety notes, progression paths — is generated from the structured record and the source instructions and anchored to the source; nothing is invented, and where the upstream data is ambiguous the field is annotated or omitted rather than guessed.

Sourcing standards

We publish only data that comes from open-licensed public sources, and we name them on every page:

• Free Exercise DB (CC0, public domain) — the primary spine: ~870 exercises with instructions, primary and secondary muscle targets, equipment, force type, mechanic, level, and category.
• wger.de (AGPL) — supplementary muscle-targeting and equipment tags, used to enrich records where the primary source is sparse.
• Compendium of Physical Activities (Ainsworth et al., 2011) — the MET values used by the calorie estimator.

Reference terminology is aligned with NIH/NLM MeSH and CDC physical-activity guidance. We do not scrape commercial fitness sites or influencer content, we do not republish anyone's proprietary program as our own, and we do not assign our own difficulty or effectiveness scores beyond what the source data supports. Synthetic equipment variations are algorithmically generated from the base exercise and clearly marked as such.

Accuracy and validation

Because values are read straight from the source files, the most common limitation is the underlying data rather than a transcription error. The pipeline applies systematic checks before a value is published: it counts only attributes the source actually records (never treating a missing value as a zero), shows a field as unavailable when the source omits it, and reconciles muscle, equipment, and category rollups so the same figure is consistent wherever it appears.

When we find that a displayed value is wrong, we fix the cause, not the symptom: we trace it back to the data layer, correct the derivation or labeling rule there, and regenerate the affected pages, so the same class of error is resolved everywhere at once.

Editorial independence

PlainExercise does not accept payment, sponsorship, or promoted placement in exchange for how an exercise is presented. We sell nothing and endorse no products. Our only revenue source is contextual display advertising served by Google AdSense; advertisers have no influence over what we cover or how any page ranks.

Update schedule

We refresh the database periodically from the latest releases of the upstream datasets and re-stamp the affected pages so the published date reflects when the data genuinely changed. We do not bump dates without a real data change.

Corrections process

If a figure or instruction looks wrong, please tell us. We follow the same process every time:

1. Report. Email hello@plainexercise.com with the page URL and the detail you are questioning.
2. Verify. We check the value against the source record for that exercise, muscle, or equipment type.
3. Fix at the source. If it is wrong on our side, we correct the underlying data or derivation rule and regenerate every page it affects.
4. Note it. If the value is correct but reflects a known limitation of the source data, we explain the caveat rather than silently changing it.

Contact

Questions about our standards, methodology, or a specific page are welcome at hello@plainexercise.com. For more on what the data covers, see our About page and methodology. For how to use this information responsibly, see our disclaimer.