Transverse abdominis-- innermost abdominal muscle it's very thin and wraps around our organs like a corset. To get a flatter stomach suck your navel in as much as you can with EVERY exercise, and breath out forcefully (all the time whenever you think about it everyday!) . Using this strong breathing technique is one of the only ways to strengthen your T.A. because of the shape and placement.
Internal Oblique/external oblique-- thicker muscles that work together to get rid of love handles, and give you that sexy trim side, plus "surfers line." The direction of the internal muscle fibers go from our midsection diagonally down toward our hips like a ^ shape. The direction of the external muscle fibers go from our midsection and go up diagonally like a v-shape. Bare down, suck in, and Twist, Twist, Twist. The rotation will strengthen this awesome couple. Some examples: standing cable woodchop, med ball trunk rotation, or alternating bicycles crunches.
Rectus abdominis--outermost abdominal muscle. The one that gives the six pack appearance. The direction of the muscle fibers go from head to toe. Therefore, any type of straight forward crunch, curl, sit-up, reverse crunch etc will strengthen this baby.
*While doing any abdominal exercise it is very beneficial to always suck in,bare down and breath out during the exertion*
please feel free to contact me if you have any questions regarding this information.