Whats the difference between a situp and a crunch?!
Question: how do you do a crunch?
Answers: how do you do a crunch?
You don't go all the way up to your knees like you do with sit ups. Go about 1/2 way, till you feel it in your upper ab area. Crunches are a bit easier on your back as well.
You have to situp on the couch to crunch into your next bag of Lays chips.
the same way as a sit up, but focus more on "crunching" your ads and holding it.
in a situp, you are using your back muscles primarily, to get all the way up, not good. In a crunch, you are tightening your abdominal muscles to pull your chest and shoulders off the floor, not all the way into a siting position as with situps. Much more effective in developing your abdominal muscles.
The difference between the two is that while doing a sit up you go all the way up towards your legs, and doing a crunch you don't go all the way up.
Sit ups were the thing when I was training at school; straight legs hooked under the wall bars, straight back and hands behind the head. Hit the muscles alright, BUT used the thighs too much and put far too much strain on the lower back. AWFUL.
Strict crunches are more effective and safer. Knees bent, abs at 60-70% tension, hands at temples but NOT lifting the head, (which hurts your neck), curl up slowly lifting your shoulders off the floor, holding a mo' and then slowly down again.
If you really want to mix it up, try doing the crunches whilst sitting on an exercise or 'swiss' ball.
However, crunches need to be supplemented with bent knee, leg raises as they don't fully hit the upper abs; and oblique v-ups for the oblique or 'side' abs.
Throw in bridges and side bridges and you'll be fine.