A study conducted by the University of Wisconsin compared 16 abdominal exercises, looking at which one activated upper and lower abs the most. It found that no exercise was able to top the standard crunch for engaging both the upper and lower abs. That doesn’t mean a little variation is out of the question. Crunches with knees up can really home in on the upper abs. You can also throw in reverse crunches (curl up from the pelvis) to ensure good contractile activation of the lower abs. Twisting variations of crunches can also be included to ensure good activation of the obliques. Although high reps are considered the best for abs, they can also bene t from progressing the resistance and reps over time, especially if your abs appear too at or the cuts appear not deep enough. A five- to 10-pound plate held behind the head or across the chest can effectively increase the resistance. Reps in the 10 to 12 range are perfectly acceptable while using added resistance. Reps and weight should be cycled from high to low with appropriate periodization, just as you would with other muscle groups.


  • Abdominal Crunch Machine
  • Cable Crunch


Crunches, and core work in general, should be done at the end of a workout to avoid compromising core strength and stability for big compound movements. The order that you do crunches and reverse crunches should be dictated by which area needs the most improvement.


The rectus abdominis (RA) begins at the pubic bone, runs up the length of the torso, and inserts at the fifth to seventh ribs. It serves to flex the trunk, pulling the rib cage to the pelvis. The RA is flanked by the internal and external obliques that assist the RA and help rotate the torso.


  • Crunch | SETS: 3 | REPS: 12-15
  • Reverse Crunch | SETS: 3 | REPS: 10-15
  • Twisting Crunch | SETS: 3 | REPS: 15-20