Substituting an Exercise

When to substitute

Real-life reasons:

• The squat rack is taken — no barbell back squat.
• Your shoulder is twingy — barbell bench is sketchy.
• You forgot your dumbbells.
• The exercise just doesn't feel right today.

Don't skip the muscle group — substitute.

Step-by-step

1. In the execution screen, on any exercise card, tap Substitute Exercise.
2. The ExerciseSubstitution modal opens.
3. The system shows alternatives from /api/exercises/alternatives. Each alternative is filtered to:

• Same primary muscle group (e.g. chest)
• Compatible equipment (or "anything available")
• Similar difficulty

1. Tap the alternative you want.
2. The current exercise is replaced for THIS session only — the program template is not modified.
3. Continue your workout.

How alternatives are picked

The /api/exercises/alternatives endpoint scores candidates by:

• Muscle group overlap (primary + secondary)
• Equipment match
• Movement pattern (push / pull / squat / hinge / carry)
• Difficulty within ±1 of original

Top 5-10 results are shown. The original sets / reps / RPE targets are kept.

What your trainer sees

Your session log marks the substitution explicitly:

• Original exercise name struck through.
• Replacement name shown.
• Tag: [substituted].

If you keep substituting the same exercise repeatedly, it's a signal — message your trainer about it.

Permanent vs one-time

• One-time substitution — just pick from the modal. Affects this session only.
• Permanent change — ask your trainer to update the workout template. They can edit it for all future occurrences.

Common pitfalls

Where to find this

• Trigger: any exercise card during workout → Substitute Exercise.
• Component: ExerciseSubstitution.
• API: GET /api/exercises/alternatives (query params: exerciseId, equipment).