Thanks MT
Generally it'll probably bodyfat - most men tend to store fat below the bellybutton and on the obliques.
However, leg raises and weighted leg raises are good. I do a lot of core-centric compound exercises, like squats, deadlifts to name a few.
You can do sit ups etc.. but unless you have a lower bodyfat percentage it won't really make much of a difference - and sit ups aren't the best ab exercise IMO.
90 degree leg chins work well too but are hard!
DB pull ins are also good for some core development.
I don't do a heck of a lot of ab work if I'm honest. If you get a training partner you can interlock your legs with a medicine ball and do alternative sit ups and throw the ball to one another and control it on the way down.
Static holds are quite good too. Remember it's also just a muscle (believe it or not it's 1 muscle, not 6/8) - so some good resistance work will help develop it.
The only thing you have to be careful of, is too much heavy ab work will generate an unneveness, and could lead to a painful lower back.
and leaning up further, in a natural show, from looking at heavyweights/higher middleweights, you'd clean up mate, seriously
I've been at this for years now, I've spent a lot on learning about how to do this, how the body works and asking a lot of questions!
