Start seated on the ground or on a weight bench. Place your hands about an inch behind your back with your fingers facing forward. Your feet should be on the ground.
Lift both feet up off of the ground and extend both legs as you simultaneously lower your upper body. Be sure to get full extension at your hips and legs.
With control, bring your legs back to your chest without touching the ground with your feet, and return to the starting position.
This counts as one rep. Do as many reps as you can for 30 seconds.
For a more challenging variation, do this move lying flat on your back. Make sure your lower spine is pressed against the floor to fully engage your core.
