To get tight abs with a thin waist when you are standing sideways with the nice v shape and outlines on the side you need to work your whole core. The core is comprised of many different muscle groups that move in different ways but to simplify the most obvious are the Rectus Abdominis the outer layer that we see as the six pack, the Transverse Abdominals the inner layer which works to support the spine and the Obliques which are more on the sides of the stomach which assist in rotation or twisting. Working all these aspects is important for having that toned look but also for having a balanced, functional core.
Hands down one of the best exercises that works the whole core are Rollouts with a Physio Ball. For my Girls On Top program last week we did our strength workout with the ball and did exactly this exercise. My abs from top to bottom were sore for days.
