Ultimate Plank Workout (com.zumzet.ultimateplankworkout) on Google Play
The ultimate plank app- a lot of default plank workouts to choose from- create your own workout combining exercises from a big list- counter for the time of each position with sounds to change it- you always know the next position so be prepared for it.How to use it- put the phone on the floor- stay in plank- stay with an eye on the phone to know when to change the position and how much time you need to hold