I don’t know where it started, but somewhere along the line it became fashionable to perform massive quantities of abdominal exercise. My guess is that it may have started with the military fitness tests. They all have a muscle endurance component that tests how many sit-ups or crunches a person can do in a fixed amount of time.
So maybe since you have to do a lot of reps to pass these tests, and you have to be in good shape to pass the test, and you have to be in good shape to have washboard abs, maybe everyone just assumed that doing a lot of reps is what leads to washboard abs? I haven’t seen any other theories, so that’s what I’m going with.
Anything that you see or read now has moved away from this practice. Most experts suggest limiting abdominal repetitions to 8-15 per set, and doing 2 0r 3 sets of 2 or 3 different exercises that target the abs in dissimilar ways. But it seems to me that a lot of people are still stuck doing things the old-fashioned way, cranking out sets of 25, 50, 100, or more.
Here’s my advice…set your sights on quality and intensity instead of endless repetitions. The abs work the same way as any other muscle in your body. Slow down, keep your form strict, and take the exercise through its entire range of motion. If you can do 20 reps, find a way to make it harder.
For an abdominal routine to be effective, you have to really feel it. If an exercise has you crying for your mommy after 6 or 8 reps, that’s a keeper in my book.