This is my favorite ab workout. I do this after my full-body workout from my book, “Fat Burning Secrets”, which you can get on Amazon at http://mybook.to/FatBurningSecrets. If you are not going to do this after a workout, I highly recommend you do a thorough warmup prior to doing this HIIT workout. As an added bonus to my followers, I have made audio specifically for HIIT workouts, and they are yours free at: https://www.dropbox.com/sh/zyqzmi7v34bwdt6/AABgGXPZ_f-QvV3TDPSEpvska?dl=0. Enjoy.
You may also like my post on HIIT Cardio Emphasizing Quads & Hamstrings.