When I was in my 20's, I was very thin, and had no fat in the midsection, but nothing that could be called a six-pac; some defination, but no cuts. So horsefeathers to those who say ab training is diet. low bodyfat will show them, but if there's nothing much there, nothing much shows!
Before, when I learned all of this, I was working out at home. Then I did
crunches with a plate on my chest, and always striving to make the plate
bigger. I also did weighted bridges. Bridges are an exercise where you start,
basically, in a pushup position, but you bring your hands about 18 inches closer
to your feet, so your back is arched. Then you lower your torso to the floor,
and raise it again trying to use just ab power. (you can't help but get a bit
of lat. and hip flexor in there).
I had Larry (my workout partner, then) hold weight on my butt,
but as my abs. grew stronger, I began having my daughter sit on my butt. (she was
about 90 lbs (41 Kg.) then, and I eventually had her hold dumbbells) *grin* she enjoyed
the ride! Before I joined Gold's I had worked my way up to Larry on my butt
for 12 to 15 reps.
( he's 160 lbs (72 Kg.)) By then, my abs showed a bit even at 15% bodyfat.