IsoTimer

The Isometric Exercise Timer is designed to follow the 30/60/90 second isometric protocol for overcoming isometric exercises. Overcoming isometrics are strength exercises where you exert maximal force against an immovable object or resistance. Examples include a bicep curl with a strap or long towel, or an isometric squat using a forearm forklift strap wrapped around your waist and looped around your feet.

The protocol is 30 seconds moderate effort, 30 seconds hard effort, and the final 30 seconds as hard as you can (while staying safe). The app timer beeps and changes colors upon each transition. There is also a delay start so you can get into position before the timing starts.