DIFFERENCE BETWEEN SIT UPS AND CRUNCHES????

Can anyone please tell me the difference between these two?  Which is better?  I go to the gym 5 - 7 days a week and do 125 - 150 sit ups each time I go, along with other weight training and the elliptical.  Should I do crunches instead?????

Jillie, the first question I have for you is what is the main reason that you are doing the abdominal exercise? The second is, do you have any back or neck problems? Third, how do you do your situp?  A sit up is typically done with the knees bent, feet on the floor (sometimes under something and sometimes not) and you raise all the way up until your chest or arms are close to the thighs.  A crunch is usually done with a similar starting position as the situp, but  the subject presses the low back arch flat against the floor and just raises the shoulder blades off the floor to the point where any more movement would result in the low back coming off the floor.  Crunches typically are recommended for people with back or neck problems becasue they put less stress on the trunk and spine areas.  Depending on the answers to your questions, it would benefit you to do a variety of abdominal exercises including but not limited to either of the above.