Hello Christian!
Anything that pulls the knees toward the chest is working the lower abs. Unfortunately, the lower abs, even though cut, remain pretty much smooth looking on just about everyone! It's just how we are made, and there is really nothing that can be done about it! If the upper abs are well defined and the lower still look pretty much smooth, chances are, it will be that way no matter what you do!
Keep Blasting!
Sifu Lamar M. Davis II
Senior Instructor
Hardcore Jeet Kune Do
Sifu@HardcoreJKD.com
http://www.HardcoreJKD.com
Kwoon (205) 274-9011
"Hit Hard, Hit Fast, Hit First - ALWAYS!"
"What is Jeet Kune Do (JKD)? Chinese martial art, definitely! It is a kind of Chinese martial art that does away with the distinction of branches, an art that rejects formality, an art that is liberated from tradition." __Bruce Lee