Worst Abdominal Exercises
Bent-over twist -- The person bends forward at the waist at a 90-degree angle and then twists from one side to the other. The spine and ligaments do most of the work in this exercise, so excessive use of this exercise can put unnecessary strain on both those parts.
In addition to these five exercises, a number of abdominal machines are ineffective and potentially dangerous. The electronic ab stimulator does not really do anything. The ab rocker is about 80 percent less effective than the traditional crunch done properly.
The bottom line for great abs is that they take time, but you can help yourself by making sure the exercises you are doing actually target the inner core muscles without damaging the lower back.