Crisscross your way to lower-ab fire.
Keep your lower back pinned down the whole time to protect your spine.
Holding both legs off the floor puts your lower abs under constant tension, and the crossing pattern adds a coordination demand that keeps the set honest from first rep to last. Your core is not just holding a position, it is resisting the pull of two long levers swinging across each other. Everything hinges on keeping your lower back pressed down, which is the real work of the exercise.
Your legs are heavier levers than your abs can currently control at that height. Raise your legs higher, keep your hands under your glutes, and stop the set the moment your lower back peels off the floor.
Flutter kicks move the legs up and down alternately, scissor crossovers cross them over each other side to side. The crossover pattern adds an extra control element, but both hammer the lower abs through a held leg raise.
Either works. Time is simpler since the legs move continuously, so try steady sets of 20 to 30 seconds with your lower back pinned, and extend the time as you get stronger.
