What is the first action in the process of the Roll Up?

The first action in the process of the Roll Up is curling the upper body forward. This initial movement is crucial because it sets the stage for engaging the core muscles and articulating the spine correctly as the exercise progresses. When you curl the upper body forward, you initiate the flexion of the spine, which helps to lift the torso off the mat while reaching towards the feet. This movement activates the abdominal muscles and helps to create the proper alignment and control necessary for the rest of the exercise.

In the context of the Roll Up, the other options represent different stages or aspects of the movement. Raising the feet into the air or leaning back with legs extended would occur later in the sequence and are not foundational to achieving the correct form. Extending the arms behind the head can serve as a preparatory or ending position, but it does not initiate the Roll Up itself. Therefore, focusing on curling the upper body forward is essential for successfully executing the exercise.