API DocsAPI Docs / GET /api/v1/training/workout-plans/{workout-plan-id}/muscle-load

There are no query parameters and no request body.

How the load is calculated

Per prescribed exercise, per muscle-group credit:

Effective reps

effective_reps is what one prescribed set asks of the muscle, from the exercise's set structure:

Each drop or mini-set is credited the reps of the top set, an approximation that errs toward the work done. A range's midpoint may be fractional (8–11 → 9.5). planned_set_count stays the prescribed sets: the drops and mini-sets live inside them. No set technique sends a row to unparsed_exercise_count.

type_factors are returned in every response so a client never has to hard-code them:

A secondary mover must not be credited the same load as the target, which is what the factors are for. They live on App\Repositories\Tracker\Workouts\TrackerMuscleLoadRepository::TYPE_FACTORS (the same constant the tracker report uses) so the response, this page and the arithmetic cannot drift apart.

planned_rep_load is not volume_load

workout_plan_exercises carries no weight column: a plan prescribes sets and reps, not load. The tracker report's reps × effective weight therefore cannot carry over, and this endpoint's unit is deliberately named planned_rep_load instead. The two figures differ by two to three orders of magnitude and must never be added, diffed or plotted on one axis. The response says so on the wire with "unit": "planned_rep_load" and "comparable_to_volume_load": false.

Only the normalized 0–1 shapes of the two endpoints may be laid over one another: that is what lets "what the plan intends" and what was actually trained be drawn on the same body map.

Exercise groups

Supersets, tri-sets, giant sets and circuits (exercise groups) do not change the load: grouping says how exercises are sequenced, not how much each prescribes. Every member is summed on its own, with no de-duplication: none is an empty container, since set_count and rep_count are NOT NULL and every write path validates them required|integer|min:1.

Prescribed rows this report cannot use

set_count and rep_count are string columns that predate the integer|min:1 validation every current write path applies, so a legacy '', 'abc', '0' or '-3' is possible. An exercise counts only when both read as at least 1, and, when it has a range, rep_count_max is not below rep_count (no write path accepts that; only a row written directly could hold it). A row that credits no muscle group at all (its catalog entry has no muscle-group mapping, or every mapping carries a role outside type_factors) cannot be counted either. In every one of those cases the row contributes nothing and is surfaced rather than silently dropped:

• unparsed_exercise_count at the top level: distinct exercise rows in the whole plan that contribute to no figure, whether because their counts could not be read or because they credit no muscle group;
• the same figure per session;
• per group, how many credits to that group were skipped because the counts could not be read.

A non-zero count is a client's signal that the figure beside it is short.

The numbers are not additive

muscle_groups is a flat list. Back sits beside Lats, Upper Back and Rhomboids, and an exercise mapped to a region and to a muscle inside it credits both. Summing the groups therefore overstates the prescription, and the response carries "additive": false to say so.

For the same reason normalized is each group's share of the largest group, never of the sum. The largest group is always exactly 1; when a scope has no credits at all, every normalized is 0.

Number formatting. Every numeric field is a JSON number, and a whole value is emitted without a fractional part: 1, not 1.0, and 96, not 96.0. A client in a strictly-typed language should read these as a floating-point type that accepts an integer literal (in Dart, num or (value as num).toDouble(), never a bare as double).

Two normalization scopes

This is the one subtlety worth reading twice:

• plan-level normalized is against the largest group in the plan;
• a session's normalized is against the largest group in that session.

So a light training day's shape still reads on its own, which is the point of a per-session figure. Cross-session comparison is served by the absolute planned_rep_load, which is on one scale everywhere in the response.

Each scope is rounded independently, and the plan total is folded from the unrounded session figures. The plan's planned_rep_load is therefore the authoritative one: summing the displayed per-session values for a group can land up to a cent per session away from it, which is worth knowing before building a stacked bar out of them.

Caching

Results are cached for ten hours under the workout_plan_muscle_load tag, keyed on the plan ID alone: there is no window, no share and no viewer-dependent substitution here, so every viewer of a plan gets the same numbers. Any write that can change a prescribed exercise (creating, updating or deleting a plan, a session or an exercise itself) flushes the tag after the write, so an edit is reflected on the next request. The flush is coarse on purpose: deleting a plan or a session cascades its exercises away without any per-row repository method running, so a narrower invalidation would miss the case that changes the most rows.

Two writes deliberately do not flush, because neither can change a figure: creating a bare plan (it has no sessions, so no prescribed exercises) and deactivating a user's plans (it writes is_active, which is not an input to this report). Since the flush is tag-wide, an inert one on either would drop every other user's cached report as well.

Response

200 OK

Both groups arrays are ordered by planned_rep_load descending, ties broken by muscle_group_id: matching the tracker endpoint's order. sessions is ordered by workout_plan_session_id, so it reads in the order the sessions were authored.

Every session appears, including one with no exercises ("groups": []): an empty training day is information, not an omission. A plan with no sessions returns "groups": [] and "sessions": [] with status 200, not an error.

No MCP tool

This endpoint has no equivalent on the MCP server, and that is a deliberate deferral rather than an oversight. Neither this report nor the pre-existing GET /api/v1/tracker/data/muscle-load is exposed as a tool today, so adding one here alone would leave the pair inconsistent. The tool would be a read-only mirror of can:view,workoutPlan with no premium gate, in the shape of compareWorkoutPlanToGymEquipment; it belongs in a change that covers both reports at once.

Error Responses

403 covers both a caller without workout_plans.view and a caller who has the permission but no relation to the plan. 404 is a plan ID that does not exist.