Butterfly sit-ups

Muscles worked

You need

How to do it

1. Lie on your back with the soles of your feet pressed together and your knees dropped open to the sides, arms extended on the floor overhead.
2. In one smooth motion, sit all the way up and reach forward to touch your feet, then roll back down with control, one vertebra at a time.
3. The butterfly leg position takes your hip flexors out of the lift, which is why it's harder than a regular sit-up - your abs do all of it.