Sit up with your legs straight out in front of you.
Loop a resistance band around your foot to be exercised, holding the ends in each hand.
Place your other foot inside the loop and cross if over the front of your other shin.
Press this foot into the resistance band, creating some tension in the band between both feet.
Keeping your upper foot still, turn your lower foot inwards against the resistance of the band.
Ensure your leg stays straight with your knee pointing directly up towards the ceiling.