In yoga the navasana is a pose where you lie on your back and then lift your legs up at 90 degrees and then slowly lower it down to 30 degrees to feel your abdominal muscles getting challenged. It is even more challenging when you try to lift your upper body up so that you are sitting on your butt with your body in V shape position.
In Pilates, there is a similar posture called the teaser. It is fun to do and you get to feel your tummy burning. A resistance band can also be used to challenge those muscles. You just need to place the resistance band around your legs and lift your body up as you move into the V shape position.
