Lengthen Your Core
"I don't believe in the basic crunch. I like to work the core differently than I would the rest of the body with a focus on isolations. You create isolation by never letting the core relax; always keep your shoulders off the floor and your core contracted so that it fatigues quicker. Most people have a tough time working the core because they use their neck to pull them up. I always stick a towel behind my head so that my abs are completely contracted, relaxed, and all the energy stays in my core. Basic yoga moves like downward dog and crescent twist lengthen the torso and the muscles around the obliques as well. As you move into both of these poses, you are also working your lats in a lengthening fashion."