Accomplishing crunches over a Swiss Ball or BOSU Coach may help improve your harmony and balance. And because you're with a spherical surface, you've got a better selection of movement, which raises the problem. (Bonus: This exercise ranked third for ab muscle mass activation within the 2011 ACE review.) http://sergiodwlzl.aioblogs.com/23356320/5-easy-facts-about-crunches-exercise-for-belly-fat-described