Do the workout in varying speeds.
You need to mix it up a little. It is a must to perform your abs workout in a normal pace and the “fast-forward” pace? How come it is important? Well, the Journal of Strength and Conditioning Research, in their 2008 edition, published a study about this and they found out that as the speed progresses, the four muscles in the abs works more. This is what you need if you long for defined abs.