The Ab Crunch is King
The study recruited 16 healthy volunteers between the ages of 16 to 24 years old. Each participant practiced each exercise in the study along with exercises from several highly advertised ab equipment. The equipment free exercises included the following: the yoga boat pose, the plank, the side plank and the bicycle crunch. The exercises utilizing ab equipment were the Ab Circle Pro, Ab Roller, Ab Lounge, Perfect Sit-Up, Ab Coaster, Ab Rocket, Ab Wheel, Ab Straps, the stability ball crunch, decline bench curl-up, and the captain’s chair crunch. Researchers placed electrodes on the upper and lower rectus abdominis (URA and LRA), external obliques (EO) and the rectus femoris (RF) of each subject and measured the maximum voluntary contraction (MVC) of theses muscles during the performance of the above exercises.
The FindingsResearchers found that none of the exercises elicited greater muscle activation than the good old basic crunch. In fact, the Ab Wheel*, Ab Circle Pro, side plank and front plank all had significantly lower muscle activation in the upper and lower abdominal region compared to the traditional crunch.
*The Ab Wheel only had a significant lower muscle activation in the upper ab region
They also found that there isn't any significant difference between the upper abs and lower abs. When performing abdominal exercises, you can't selectively work the muscles in the upper abs versus the lower abs. This was found in all of the exercises performed above.
As for the basic or traditional crunch itself, there is no difference in muscle recruitment if you put your hands on your chest as opposed the back of your head and neck. It has been long thought that some individuals put their hands behind their head and wrench of their body up and forward when performing the crunch, which is considered bad form. As you can see, that there was no difference in muscle activation between the two types of crunches.
As far as the external oblique muscles this is what the researchers found:
The plank is still one of the best exercises to do when you are trying to work the transverse abdominus which helps to stabilize the spine. Even though the plank didn't significantly effect the rectus abdominal muscle, don't drop it from your workout because there is no single ab exercise that effectively challenge all of the muscles of the core.
The Bottom Line
If you don't have a lot of money to spend on equipment and you want to work your core, the basic crunch will do the job very nicely. However, if you would like to buy some ab equipment to make you commit to an ab routine, most of the machines above except for Ab Circle Pro will do just fine.
What do you think of the University of Wisconsin La-Crosse's findings? Read the complete study here.