If your abdominal muscles are not strong enough to do good sit-ups, begin with crunches (partial sit-ups). Assume the sit-up position as described, but slowly raise only the head and shoulders off ...

Inverted sit-ups. From an inverted position, place your hands behind your neck and point your elbows toward your knees. Using your abdominal muscles, ... This is only a partial list, ...

The group tested 15 healthy young adults performing six types of sit-ups: partial sit-ups (also called crunches, lifting the shoulders about six inches from a supine position) on the floor; full ...

If you’re not sure how to do any of the exercises, watch the short video above, especially for the partial sit-up. Also, make sure you have something soft beneath you to support your back.