Sit ups vs. Crunches???

In the local Pilates session, we do crunches, leg lifts, but lifts, side crunches, planks, swimming and varieties of those but we don't do full situps because it puts a lot of pressure on the back.

they say crunches are better because sit ups are often done incorrectly and people do the whole "swinging" motion and rest more than get the benefits. I usually do leg raises and crunches with either my feet in the air knees bent or sort of in a "butterfly" position with the bottoms of my feet together. Planks are great too. I like the guided machines for obliques and abs. Technically... abs are one muscle, so the whole "upper and lower" abs thing doesn't really exist... its all just one muscle that has different levels of tone. the obliques however are more towards the side of your torso and are the "love handles" part of the body. i hope that helps!