When training only retraction takes Occiput-C1 and C1-C2 to their full end-range of flexion. The Pendulum 4 and 5-Way Neck strength curve was designed to include retraction during the head and neck movements. When you begin a neck flexion exercise keep your body erect and let the face pad push your head slightly backwards. This brings the Occiput-C1 and C1-C2 into a position to begin full range neck flexion.
Start the Exercise from Neutral
Keep the Body Straight and let the Head Retract slightly before Beginning the Rep
Head and Neck Flexion on the Pendulum 4-Way