Picture the legs of a sprinter, then think about those of a marathoner. It's power versus endurance, and the comparison helps explain why speed training will help you develop massive abs. Toward that end, part five of this series focuses on performing each movement as fast as possible, which forces even the hardest-to-work muscle fibers to contract maximally, resulting in bigger, more powerful abs. (Read Part 1, 2, 3 and 4.)

Perform this workout 2-3 times a week, resting at least a day between each workout. Do the exercises as straight sets, completing all sets of each one before moving on to the