5. They often create tension and restriction in the hips.
Most individuals tuck their butt under as they do crunches.
This again overworks surface muscles, disengages more core muscles, tightens hip flexors, and can create tension in the hips.
The habit of tucking also produces unwanted results in the hip joint that can also manifest as lower back pain.
6. They can create tension and pain in the neck.
Ever watch someone do a lot of crunches? More often than not you’ve seen the strained look in their face and the taught tension in their neck.
Another indication that crunches forget that the connection of the entire spine, doing more harm than good.
7. They do not consider the whole body.
As already mentioned, crunches neglect deeper core muscles, critical aspects of the spine, as well as the role our core plays in the whole body.
True core training acknowledges that the whole body is connected.
Working for a six pack at the neglect of everything else is dangerous and a waste of time.