I built Isometric Hold Lab for static-strength sessions where the hold may end before the target. Press START when form breaks and the app records actual time under tension instead of awarding the planned duration.
It supports dead hangs, planks, wall sits, side planks, grip holds and a configurable custom protocol. Bilateral sessions compare left/right TUT and asymmetry, while the watch keeps adherence, best hold and the last completed session.
I am the developer. The app is completely free, offline and requests zero permissions. It is a manual timer, not automatic exercise/drop detection or medical, rehabilitation or safety equipment.
Store: apps.garmin.com/.../23f723a1-30bc-42f4-ae92-774757713dcb