Advanced Plank Workout

How many of you have done this one before?

This Advanced Plank Workout is tough, fast-paced, and requires you to have a good deal of existing core strength and flexibility.

It's definitely not for beginners, but if you’re ready, planks are a great measure of core strength and endurance, and go far beyond helping out with a flat stomach. This routine will definitely keep your body guessing, as different plank variations use similar muscle groups, but from different angles, providing a very comprehensive challenge.

In fact, with some of the variations, you’ll be using muscle groups that are otherwise a little neglected in a traditional version.

So, if you've done it before, what did you think? Would you recommend it to a friend?