The consequence of being told a long time ago that crunches only had to be done up to the point where the shoulders raise off the ground, is that the middle part of my abdominals is comparatively under-developed.
In fact I have really strong and large abs, albeit buried under a layer of blubber that even a sperm whale would be proud of.
However, my abs bulge near the sternum and bulge near the navel and sort-of hollow in between.
In abs-classes at the gym I have found that I am unable to actually sit up with abs alone, I'm fine with the first part of the crunch, but cannot lift the part of my back from shoulders to spine from the ground using my abs.
One way to fight this, I was told, was to do negatives where I use the abs to resist a lying down motion, but again I find that between base of spine and shoulders there is simply no strength at all and I have to resort to using my arms holding onto my legs to prevent myself falling backwards during this part.
Here comes my discovery. At home I favour using an ab-roller to support my neck and shoulders during crunches as Ihave a history of neck problems. I discovered this week that by pulling with my arms on the forward bar of the abroller I am able to roll right up to a sitting position and that doing multiple reps this way targets my abs in a way that nothing else does!!! Too early to say if this will alter the shape of my abdomen, but I thought it was a tip worth passing on.
However, in the gym the other day my ghast could not have been more flabbered than when one of the people in the gym picked up a reebok step, peeled back the top, and positioned an internal pin to turn the top into the back of an upright bench!!!!
I honestly didn't know they could do that
Could not have been more astonished if someone had come into my garden, opened a rock and pulled out a chair!!!!
I'm inclined to think that if something doesn't work, it doesn't work for a reason, so you find out what the reason is and find an alternative method that DOeS work.
As long as the alternate method accomplishes the same goals. In this case, targets the same muscles. I agree with mrwright's thoughts to a point. As long as the reason you can't do it isn't pain (not soreness), keep trying until you can.
I've never been a fan of regular crunches. The range of motion is very small. For that type of ab work, I like to use a swiss/exercise ball with a full sit up. You get a full ROM doing it this way and it's not hard on any other parts of the body.