Finally you feel your abdominal muscles
Most people never completely contract their rectus abdominis. Instead, they use their hip flexors during bowing and crunches.
If you can do 30 crunches, your form is disabled and your abs may not work very hard. These hip flexors do most of the work.
Do not you believe it? Try to manipulate your muscles to see how strong your abdominal muscles really are. The goal is to disable the hip flexors. We can do that by activating the thigh muscles. (This is similar to Pavel's popular Janda sit-up.)
Tie a medium or heavy band to something secure. Then you can prepare for any crunch exercise, but pull the band at the ankles. The band should be sufficiently taut and you should feel a slight thigh muscles. This will make sure your hip flexors are off.
Now do as many repetitions as you can concentrate on bending your lumbar spine and pushing your abs as hard as possible. Strive to be as high as possible, without neck involvement, just abs. As you lower, squeeze the abdominal muscles until you reach the end of the repetition.
If you do this correctly, you can not do too many repetitions because your abdominal muscles lift your body weight alone. Here are three variations that you can try:
1 – Hamstring Enabled Crunch
This is the simplest with the simplest setting. It has the least amount of room to move, but you will be amply stimulated.
2 – Hamstring-activated Swiss Ball Bang
This is more advanced, allowing for greater range of motion and stability.
3 – Hamstring Activated Weighted Crunch
If you really want to challenge yourself, add a plate or dumbbell. This is a great way to get a lot of abdominal stimulation in a short time.
After the first sentence you will probably find that your abdominal muscles are not as strong as you thought. Perform one of these variations for 1-3 sets per workout. After a few weeks, add 1-2 more sets or use a stronger band to further disengage the hip flexors and improve the connection between the mind and muscle in the abdominal muscles.
Big, thick, chunky down training
Dynamic training for Abs & Obliques