Yes — LeCoach and Intervals.icu are in a continuous two-way sync once connected.
LeCoach → Intervals.icu
Every workout you create, edit, move or delete in LeCoach is applied in Intervals.icu right away (the sync fires the moment you save). The same goes for races, notes and calendar entries such as holidays, sick days and injuries. Workout names in Intervals.icu carry a 'by LeCoach App' suffix so you can recognize them; LeCoach hides that suffix in its own interface.
Intervals.icu → LeCoach
Changes made in Intervals.icu flow back to LeCoach automatically. New activities, wellness data and edits typically appear within moments to a minute; LeCoach also refreshes in the background while you have it open. If something seems stale, refresh your browser, or run a Full Intervals.icu Sync from Settings - Integrations.
How workouts get completed
When a new activity arrives, LeCoach automatically pairs it with the planned workout for that day (matching sport and, where possible, the workout it fits best). The pair is then scored with the workout execution score. You can also pair or unpair manually — see How activities pair with planned workouts.
Removing your plan from Intervals.icu
If you delete your training plan in LeCoach, all future workouts that LeCoach created are removed from Intervals.icu as well. Workouts you created outside LeCoach and everything in the past stay untouched. See What happens if I delete my training plan?
After changing your FTP or thresholds
Intervals.icu calculates the load and intensity of planned workouts using your thresholds at upload time. After an FTP change, use 'Re-sync upcoming workouts' in Settings - Integrations to re-push your future workouts so their load and intensity are recalculated.