The roll up is well known as a foundation exercise for the Pilates flat abs effect, among other benefits.
1) Lie flat on your back, arms stretched above your head, ribcage down.2) Inhale: Leave your shoulders down and your scapula settled in your back as you bring your arms overhead, nod your chin and begin to curl your upper body forward.
3) Exhale: Continue rolling up off floor as you deepen the scoop of the abs and reach your arms forward, parallel to your legs.
4) Inhale: Begin with a deep pull in of the lower abs to start to roll back down.
5) Exhale: Continue to roll down, one vertebrae at a time.
Repeat up to six times.
For the more instructions and relevant links go to the roll up.
