Lie down on the floor. Put your hands behind your head. Keep a 90 degree angle between your lower and upper leg.
Use the strength of your abdominal muscles to raise your shoulder blades and head from the floor until your abs are completely contracted. The lower back should not leave the floor. Hold for a second.
Use the strength of your abdominal muscles to lower the torso and head back into the starting position. Repeat the exercise according to the training plan.