The seal exercise is most commonly used in pilates. It is a fun, yet effective exercise for the abs. The seal works because the abs are used to initiate the momentum of the "body roll."
Begin this exercise by sitting upright with the arms between the legs and hands secured under and around the ankles. The feet bottoms should be together. Once in position, use momentum to roll onto your back. The back should be curved (called a C-curve in pilates) at all times. Next, rock the body back and forth several times. The feet should be aligned with the head each time you roll back. The key is to use the abdominal muscles to generate momentum.
Step 1
Sit upright with bottom of feet together. Loop hands under and around ankles.
Step 2
Roll onto the upper back.
Step 3
Rock your way back up using abs to generate momentum.