Replace an exercise in a routine (permanent)

Your gym pulled the incline bench last week and the replacement isn't coming. You've been doing dumbbell incline press in its place but logging it as a substitution each time. Easier to swap it in the routine itself — once — and stop substituting every session.

What the agent needs to hear

Behind your sentence, the agent works backwards to three pieces: the exercise to remove, the exercise to add in its place, and the scope of the change — one day or every day it appears. The first two are usually obvious from your sentence. The third is the piece worth being explicit about: « swap incline bench for DB incline press on push day » is one day; « swap it everywhere » is across all days that have it.

The agent shows you a preview card with the day(s) affected, the old exercise being removed, and the new exercise taking its place — and waits for a nod before applying. Two operations rolled into one confirmation: same remove, same add, no orphan state in between.

Scope and target carry-over

Single-day vs across-routine matters because it’s the difference between a tactical swap (this day only) and a strategic one (everywhere the old exercise lived). Default behavior follows your phrasing — if you name a day, scope is that day; if you say « everywhere » or « across the routine », scope is all days where the old exercise appears.

Targets typically carry over from the old exercise: same sets, same rep range, weight blank. That’s right when the new exercise is structurally similar (incline bench → DB incline press, both push, both incline). When the substitute is meaningfully different (incline bench → cable chest fly), the agent may suggest a rep-range bump and a blank weight, because the loading patterns don’t translate directly. You can override either: « same sets and reps as the old one » preserves them as-is.

How this differs from a mid-session swap

A mid-session swap is one-time — the hack squat is taken today, you do goblet squat today, the routine template is untouched. Tomorrow’s hack squat day still queues hack squat. A routine swap rewrites the template itself, and every future session reads the new exercise.

If you find yourself substituting the same exercise three sessions in a row, that’s the signal to convert it from mid-session substitutions into a routine swap. The system isn’t strict about it, but the cleaner trail is for the routine to reflect what you actually train. Past sessions stay attached to the old exercise — your incline bench history doesn’t vanish, it just stops accumulating from this point forward — and the new exercise starts a fresh progression curve from the next session that hits this day.

When the agent gets it wrong

The preview card is the chokepoint. If the scope is wrong (agent assumed across-routine, you wanted just push day), say so: « only push day, not everywhere ». If the new exercise doesn’t fit (you said DB incline press, agent matched flat DB press), name the difference: « incline DB press, on the bench at 30 degrees, not flat ».

If the targets didn’t carry the way you wanted (you wanted the rep range bumped for the new exercise, agent preserved the original), name the change: « bump it to 3 sets of 12 for the DB version ». The card updates and you confirm again.

What makes the swap worth keeping

Three things decide whether this swap reads correctly later: the scope matches what you actually want changed (one day vs across — both are valid, but mixing them up trains a routine you didn’t design), the new exercise resolves to the one you meant (incline DB press is not flat DB press), and the targets carry sensibly (same when the substitute is similar; reset when it’s not). The system reads the template every session and silently follows whatever’s there; a wrong-scope swap or a mismatched substitution quietly retrains a day for weeks before you notice. Name the swap, the scope, and the targets — confirm the preview, and the next session reads the new exercise.