STARTING POSITION:
Lie flat on a ab bench with your legs clamped. Your knees should be at 90º. Grab a medicine ball with your right hand and extend your arm towards the roof. Contract your pelvic floor and core.
MOVEMENT:
Push your low back down in the floor and use your abdominal muscles to roll your shoulder blades off the bench while you exhale. Maintain arm with the ball always up. Return to the starting position in a smooth movement. Repeat the movement for the specified amount of repetitions and then switch sides and repeat with the other arm and leg.
TIPS: Focus on slow and controlled movement Don't separate your low back from the floor when you do the exercise.