Lean back slightly and lift your feet off the ground, bringing your knees towards your chest, to get into the initial tuck position.
Extend your legs out straight in front of you while simultaneously lowering your upper body back towards the floor, but don't let your body fully touch the ground.
Quickly pull your knees back into your chest and lift your upper body back up into the initial tuck position.
Repeat these movements for your desired number of repetitions, maintaining a rapid pace to engage your core throughout the exercise.