Lower Body Crunch
To do the Lower Body Crunch, lie on your back with our hands behind your head or down by your sides. Engage your abs using the pelvic tilt and lift your legs up off the ground, bending your knees to about 90 degrees.
Then, keeping your abs engaged and your low back pressed into the ground, straighten your legs out. Straighten them out, keeping them as close to the ground without touching as you can. Kick them out higher to make the move easier. Make sure your low back stays pressed into the ground and your abs are engaged as you full extend your legs.
Then draw your knees back in toward your chest before repeating the move.
If you struggle to keep your low back from taking over for your abs, kick your legs out higher or extend one leg at a time. You can also use one of the easier progressions of the pelvic tiltto help you learn to engage your abs.