Men's Health fitness director Ebenezer Samuel, C.S.C.S. knows how to sculpt a strong, striking core and he has the six-pack to prove it. One of his favorite exercises is not as commonly used in general training.
Eb says: Planks, hollow rocks, and stability moves are tremendous for your core (and they're the backbone of most of my ab training). Hypertrophy directly in the rectus abdominus. There's an over-assumption today that the body of the bottle is fat; that's true, but having some depth to your abs helps as well.
One movement that allows you to create abdominal hypertrophy is the cable crunch, to old-school bodybuilders move that's the basis of this ab circuit. It's a move that'll let you directly load your rectus abdominus. Do this workout correctly with a very deep abdominal burn and the muscles that help create a six-pack with visual impact.
A few keys on the cable crunch. Note the back position. In most exercises, we're preaching scapular retraction, a squeezing of the shoulder blades that's great for posture. On the crunch you actually need to protract though. Think about spreading your lats wide and thin, and allowing your entire torso to roll forward. This obviously is not good posture, but it places you in proper position to do the move; you simply can not crunch and contract your shoulder. For this exercise, let everything come forward.
The other key: Finding the right thigh angle. You want your thighs very close to a perpendicular angle with the ground, perhaps a degree or two backwards, at most. Too far forward, and the sheer momentum of forward torso lean assists you into dropping into the crunch. Too far backward, and your hamstrings assist the movement as well.
Crunch down and drive your elbows to your knees; letting your spine flex. Spinal flexion gets a bad rap days, but there's a reason your spine is capable of flexion. In this situation, it's not spinal flexion under load, either (as it is in a poor deadlift), and it's a controlled, slow spinal flexion, so you do not need to worry unless you have a history of back issues (in which case you should not be doing this move).
You can use a cable tower with a rope attachment to exercise, but in this version we're working on an exercise tape. If you do not have any on hand, check out this option from U-Powex.