Level 1 - Building the foundation. (Strengthening the entire band of the core/abdominals and preparing for level 2.) _ Level 2 - Core control. (Exercises with the lower back coming off the floor to help work the lower back and lower abdominals.) _ Level 3 - Unbreakable core - exercises that will challenge your core/abdominal strength to the max! Complete the repetitions and sets to build an Unbreakable core!