When most people think of Abdominal Exercises they think of a sit up or a crunch, unfortunately these are not one of the best posture exercises. Why? To understand this we need to look at the make up of the Abdominal Muscles.
The Abdominal Muscles are made up of 4 different muscles: Transverse Abdominus, External Oblique, Internal Oblique & Rectus Abdominus.
Each muscles layers on top of each other, with their muscle fibers being orientated in a different direction. The combined criss cross nature of the their fibers acts like a supporting corset, keeping things in good alignment and protecting the spine.
The sit up and crunch mostly work the Rectus Abdominus, also known as the Six Pack Ab. The Rectus Abdominus is the abdominal muscle furthest from the spine. Because of this it is also the muscle that is least able to contribute to stability and good posture.
A better Abdominal posture exercise is one that exercises the deeper muscles. The video below shows such an exercise.
The key to these exercises is too keep the belly button drawn in towards the spine when moving and not to let the back arch off the ground.
For these posture exercises start with 10 each leg, gradually building up to 3 sets of 10.