Here’s a bit of information about core training from my guru Mr. Charles Poliquin.
I’ve said it before I’ll say it again. Utilize fully body movements to train your core and don’t resort to crunches and sit-ups! You are only wasting your time. You get the false impression that you’re having a really good burn in your midsection by doing crunches but it doesn’t really do anything for you. Making the right food choices, strength training , cardiovascular training and rest are still the building blocks for achieving a healthy physique!