Building a powerful midsection is essential serious lifting. It also makes you look good. Choose your
reason, you need to do it.
Check out Rudolph Liska, as shown in Mark Berry's book “Physical Improvement Vol. 2”, from 1930. Berry was the Olympic coach in 1932. Remember, this was a time when the Great Depression was in full swing. Weightlifting wasn't a new thing, but you certainly did not find a gym on every corner. These guys also didn't take steroids. They simply had not been invented yet.
Liska is attacking the abs from both directions. Note, he has added weight. If you want to build bulging muscles, what do you do? You train like a bodybuilder with lighter weights and higher reps. Look at modern competitive bodybuilders, especially in the off season. Now, while forgetting about the Super Heavy Weight Class, look at competitive weightlifters. Those guys don't have big guts. In fact, their “cores” or midsections are tight and powerful. So, maybe it is time for you to pick up some weights for working your abs.
In the top photo, Liska is doing a standard sit-up with a barbell behind his head. He is not holding a plate on his chest. This makes for maximum chest expansion and range of motion with the abdominals. The first part of the exercise is pulling the barbell off the board. Make sure to use the abs to do this, not the arms or lats. The abdominals are groups of small muscles, so you should try to work them as such and in sequence throughout the range of motion. With a modern adjustable sit-up board you can modify the resistance and the muscle group emphasis merely by changing that angle.
The second photo is a sit-up board leg raise. I don't advise you to hold a plate with your feet. While, in the original photo, it looks like the plate is tied to his feet, Iron Boots would be a much safer and more effective tool for this exercise. They will also allow you to do an isolateral version, ie. Alternating Leg Raise, with adjustable weight.
Here is a great home grade ab bench for doing any of these movements.
With any of these exercises, the classic 5 sets of 5 reps are a great way to go. As you can see in the photos, Liska had outstanding abs, serratus and oblique muscles.
All the best,
“Today is a good day to lift.”