Which exercise is classified under the Reformer Family 9?

The exercise classified under the Reformer Family 9 is Jumping. This specific family of exercises focuses on the use of the reformer to incorporate dynamic movements that enhance cardiovascular conditioning, improve strength, and develop coordination. Jumping on the reformer not only engages multiple muscle groups but also emphasizes the principles of control and balance, which are fundamental in Pilates practice.

Jumping exercises typically involve a combination of spring resistance and the reformer's moving carriage, allowing practitioners to experience varied intensities while working on stability and power. This also aids in practicing proper alignment and form while in motion, which is a crucial aspect of Pilates methodology.

In contrast, the other options provided relate to different families of exercises within the reformer repertoire. Long Spine Massage and Short Box Mermaid are more oriented towards flexibility, spinal articulation, and core strength, while Rocking is focused on specific back extension movements. Each of these exercises serves distinct purposes and targets different areas of physical fitness, indicating their classification outside of Family 9.