We're now going to demonstrate an exercise that is very often done improperly and that is the abdominal crunch or sit up.We're going to first demonstrate the way this exercise is usually done wrong.Years ago we did a lot of exercises where we crunched and came all the way up and did a full sit up. And the problem with that exercise is that you're using a lot of other muscles.You're using your hip flexors and your hamstrings. It's very difficult to stabilize your lower body. He's using some momentum to come up. He's using his lower back.And he is getting some abdominal muscle fiber, but not as much as he could get if he did it properly and he did an abdominal crunch and only coming up 45 degrees.So we're going to have him place his hands behind his head, look up at the ceiling, not interlock his fingers. We're going to have him just put the fingertips behind the head.We want to relax the arms, the shoulders and the neck, look straight up at the ceiling and move the rib cage.We also want to draw the abdominals in and exhale as he comes up and then we'll get even more out of the exercise.And notice how he can easily stabilize his lower body now 'cause he's only coming half-way up.And now he's recreating a lot more muscle fiber in the abdominal area and not using other muscles as well.