There are four major muscle groups that constitute the abdominal muscle wall and each of them does something very specific. In no particular order they are Rectus Abdominis (the frontal abs which can also be divided into upper and lower abs and make up the six-pack), External Abdominal Obliques, Internal Abdominal Obliques and Transverse Abdominis which we most popularly refer to as core. The Abs Unlocked workout works them all.
Extra Credit: 30 seconds rest between sets.
