This app is very well implemented. You can set up a series of intervals and within each interval set up actions to take place at random intervals. And even better you can download other peoples timers for free. I got some great workouts this way and it made it easier for me to set up my own by modifying premade ones. The only thing I could ask for is more prade workouts to download especially total body ones. I think there are tons of crossfit and 300 style workouts that this app could totally be used for and it would be just prrfect if they were preloaded or available for download.
Lightbrazer about UltraTrainer