Crunches are much more effective than regular sit-ups because they specifically target your upper abdominal muscles rather than your hip muscles. If you're not used to them, they can cause soreness a day or two later, but it's a 'cool' soreness. A badge of honor.
Sylvester StalloneThe one thing in my films, I only kill people who need to be killed, or killers killing killers. And I believe that the violence is very justifiable.
Sylvester Stallone