STARTING POSITION:
Sit on the floor, place a rolled towel under your right knee and rest your hands on the floor behind you. Contract your pelvic floor and core while keeping your chest up.
MOVEMENT:
Fully extend your right knee. Return to the starting position in a smooth movement. Repeat the movement for the specified amount of repetitions and then repeat with the other leg.
TIPS: While your are doing the exercise, move only the legs, make sure you don't move any other part of your body.