Sit on a leg press machine and place your feet on the middle of the platform with a narrow stance.
2. Keep your shoulders and hips in contact with the back pad at all times.
3. Push your feet to the platform and raise it and remove the safety bars.
4. Grab the side handles and flex your abdominal muscles. This is the starting position.
5. Slowly lower the platform until you can no longer keep your lower back against the back pad.
6. Hold the contraction for a moment and return to the starting position.