Change the weight and number of repetitions for the better development of the abdominal muscles
Most bodybuilders stick to traditional exercises for abs like crunches, lifting legs, etc. and make them about 20 repetitions of the series. But abdominal muscles are no different than biceps that should vary your weights and the number of repetitions to develop better and avoid stagnation.
The research team from Youngstown State University held entities, men and women, workouts for abs 3 or 6 times a week, and a separate group did not do any exercise during this period. The trainees are doing 3 sets of 20 repetitions of all exercises with 30 seconds rest between sets, they are not changing the weights for the entire period. They measured the strength of the muscles of the abdomen at baseline and 11 weeks after starting the program.
Researchers surprised to find that whether the subjects were trained to stomach 3 or 6 times a week, the strength of their abdominal muscles haven't risen significantly.
Training with the same resistance, with no change in the number of repetitions, leading to sluggish even when it comes to abs.
Regardless of how many often you train your abs, the most important success factor is the diversification of gravity impedance and number of repetitions. Necessarily add weight exercises like crunches with weight,sit ups on machine, etc., to change the resistance. Alternate heavy weights with fewer repetitions (6-8), moderate severity medium reps (8-15) and light weight (or no weight) with many repetitions (15+).