Abdominal muscles are ordinary muscles, the scheme of hypertrophy (enlargement) of which is no different from other muscles.
If you choose the appropriate exercises and load so that it “goes” into the target muscle “to failure” (when you can no longer perform muscle contraction) 10-12 repetitions is more than enough (since it has been proven that the last 6 repetitions are most effective for hypertrophy when working “to failure” or almost “to failure”).
In order to understand which exercise is most effective and how to “get” the load into abdominal muscles, it is necessary to understand which muscles the ABS consist of and where they are attached.
Six pack is obtained by two things. The first is the rectus abdominis muscle. The second is 3-4 tendon bridges that tighten the rectus muscle and form 4-6 cubes.
The attachment of the rectus muscle is located on the pubic bone from below and on the cartilage of the ribs from above. This muscle pulls the ribs down (lowers the chest), bends the spine, raises the pelvis (when fixing the chest), participates in the formation of the abdominal muscles.
There are two main movements: direct and reverse twisting. With different position of the body: lying, sitting, hanging, at different angles, etc..
The main mistake in the technique of these exercises is to involve the muscles of the lower back or the front surface of the thigh when twisting, as this “steals”, and sometimes even replaces the work of the ABS.
It is also wrong to pull the head towards, and not just support it with your hands. This increases the load on the cervical spine.
Also a mistake is the static tension of the abdominal muscles. For hypertrophy of the rectus muscle, both metabolic stress and mechanical stress (due to contractions or stretches of the muscle) must coincide.
I recommend a range of repetitions of 25-30 times, increase the weight of the load more so that the “failure” repetitions are within these limits.
Thus, if you understand the biomechanics of the work of the muscle that you want to pump up, then performing any even the most exotic exercise, you will know at what moment this particular muscle is working for you.
Do not forget that no matter what the press is pumped up, it will not be visible under a layer of fat. The percentage of the fat layer at which you can see the muscles ranges from 10 to 14% in men and from 18 to 22% in women.