Trainers Reveal: The Best Abs Exercises of All Time 20 top fitness experts reveal their go-to move for a flat, sexy stomach. Passé Abs Series "This move is one of my all-time favorite abs sculpting exercises," says Andrea Rogers, a former professional dancer, certified Pilates instructor, and creator of Xtend Barre. "It strengthens the abdominal muscles while developing stability of the pelvic lumbar region. You can also amp things up by increasing the tempo." To do it: Start seated, then lean back, resting your weight on your forearms (bending your elbows behind your body, fingers facing forward). Extend both legs straight out in front of you. Bend your right knee into a ‘passé position’ by pointing your right foot and pressing the inside edge of your right foot along the inside of your left knee. Draw your abs in tight and lift your legs off the mat and towards the chest (maintaining passé position). Bring your right knee all the way up to the right side of your chest and then lower your legs (still in passé) back down, about two inches from the floor (or as low as you can). Repeat 8 times and then switch legs. Try to do 8 reps on each side, for up to 2 sets.