Quick Leg Drop

Lie down on the floor and extend your legs straight up, soles of the feet facing the ceiling. Drop one leg quickly down while bringing the other knee into the chest. The point is to stop suddenly just above the floor. After you stopped, extend the bent knee and bring both legs back up to the starting position. Do the same exercise on the opposite side.

Your lower back should be in contact with the floor throughout the exercise, as it will keep your core engaged and prevent any pressure on the back.

The sudden contraction of the muscles as you stop the movement just above the floor activate and strengthen the lower abs.