Which exercise routine without using weight to get abs?

Many Ab Exercises: Will produce great abs...Making them visible, however, is another matter. That's all about aerobic exercise, diet (clean) and calories (not too many of them). The 4 ab muscle groups are: rectus abdominis, transverse abdominis, external and internal obliques. Exercises targeting these specifically can easily be found via search. Consistency with aerobics will be key good luck!