1. First sit on a decline bench with 30-45 degrees angle with the floor with your legs resting through the pads.
2. Place your arms behind your head and lean back to the bench.
3. As you sit up twist your body with tensing your abs, directing your right elbow toward your left knee until your back is vertical, then repeat the exercise to the other side.
Tips and Advices:
1. Focus on slow, controlled movement.
2. Make sure to keep your back and shoulder straight throughout the exercise.
3. To add more resistance and intensity to the exercise you can hold a weight plate or dumbbell in your arms.